Method for evaluating durability of asphalt concrete using steel slag aggregate

Abstract

The application discloses a method for evaluating the durability of asphalt concrete using steel slag aggregate, a method for rapidly detecting the volume stability of steel slag aggregate, a method for detecting the volume stability of steel slag asphalt concrete, a method for detecting the relative strength attenuation of steel slag asphalt concrete after immersion, a method for detecting the relative fatigue life attenuation of steel slag asphalt concrete after immersion, a method for calculating the comprehensive evaluation index of the durability of steel slag asphalt concrete, and a method for calculating the comprehensive evaluation index of the durability of steel slag asphalt concrete.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a method for evaluating the durability of asphalt concrete. BACKGROUND

[0002] The poor volume stability and large variation of steel slag restrict its application in asphalt concrete pavement as a substitute for natural aggregate. The poor volume stability mainly comes from free calcium oxide and magnesium oxide in steel slag, and the volume expansion caused by the hydration of free calcium oxide and magnesium oxide to form calcium hydroxide and magnesium hydroxide can reach 98% and 148%, respectively. Although the technical specification for asphalt pavement construction in China stipulates that the broken steel slag aggregate stored for more than 6 months can be used as coarse aggregate of asphalt mixture, the hydration of free calcium oxide is slow, the period is long, and the variation of aging effect is large, resulting in insufficient aging. Therefore, when steel slag is used as aggregate in asphalt concrete, there is a risk of insufficient volume stability, and the volume may expand or even crack when it is exposed to water during service, causing serious attenuation of mechanical strength and fatigue life.

[0003] At present, the evaluation method and control of the stability of steel slag aggregate in existing standards and specifications are only limited to the water immersion expansion rate not greater than 1.8% and the free calcium oxide content less than 3%. It is difficult to guarantee the representativeness of the measured free calcium oxide content after the steel slag aggregate is ground, and the measured free calcium oxide content has large discreteness. It is also difficult to determine whether the free calcium oxide is enriched in the aggregate, resulting in the problem that the measured free calcium oxide content of the ground steel slag aggregate is less than 3%, but the steel slag aggregate still has the problems of volume expansion and cracking after immersion in water. The stability of steel slag powder is qualified, but the stability of steel slag sand and steel slag aggregate is not qualified. The limitation of the method for detecting the free calcium oxide content after grinding is large, and the representativeness is insufficient, which is confirmed by the quality problems caused by steel slag in actual engineering. Some studies use high-temperature and high-pressure autoclave method to detect the stability of steel slag aggregate. Due to the high temperature or pressure, the conditions are too harsh, which is seriously inconsistent with the on-site use environment of steel slag, causing the detection results of steel slag aggregate to be difficult to meet the standards, artificially magnifying the volume stability problem of steel slag aggregate, and actually hindering the application of steel slag aggregate. The evaluation method for the volume expansion of steel slag asphalt concrete only requires that the expansion amount is not greater than 1.5% after immersion in a 60℃ constant temperature water bath for 72 hours. Due to the short immersion time, the small porosity of steel slag asphalt concrete, and the fact that the steel slag aggregate is wrapped by asphalt, it is difficult for water to enter the interior of the steel slag aggregate and react with the free calcium oxide, resulting in that the volume expansion amount meets the standard after 72 hours of immersion at 60℃, but the durability problems such as expansion, cracking and pulverization of individual steel slag aggregate, and cracking of the test piece occur after further immersion. In addition, the existing method is difficult to determine the number of steel slag particles that expand, crack or pulverize, and the causes of crack generation and expansion in asphalt concrete, indicating that the existing test method has great limitations, and it is necessary to propose a more intuitive and rapid detection and evaluation method.

[0004] Steel slag asphalt concrete has the risk of volume expansion and even cracking when exposed to water, which can cause mechanical durability problems such as strength and fatigue life attenuation, but the current durability detection and evaluation method and control index of steel slag asphalt concrete have not been established. The current asphalt pavement construction technology specification generally uses immersion residual stability and freeze-thaw splitting strength ratio to evaluate the water stability of asphalt concrete, but since the immersion time is only 48 hours, and the freeze-thaw uses-18℃ freezing for 16 hours and 60℃ melting for 24 hours, the actual effective immersion time is short, and it is difficult to reflect the slow hydration characteristics of free calcium oxide in steel slag and the problem of water penetration after being wrapped by asphalt, so the above two methods are difficult to evaluate the strength stability of steel slag asphalt concrete after immersion.

[0005] Asphalt pavement bears the action of repeated vehicle tire load during long-term use, so asphalt concrete is required to have good fatigue resistance, but the current specification is still blank for the immersion fatigue detection method and control index of steel slag asphalt concrete. The stability of the aggregate itself is not considered in the traditional asphalt concrete fatigue test, which leads to the unclear strength and fatigue resistance attenuation law of steel slag asphalt concrete after immersion, so it is necessary to carry out comparative test of natural aggregate and steel slag aggregate asphalt concrete to establish the corresponding baseline and control index with natural aggregate as reference.

[0006] In summary, steel slag aggregate has the problems of poor volume stability, low activity, large variability and long digestion aging time, and traditional methods are difficult to quickly and effectively detect and evaluate its volume stability. The asphalt concrete prepared by using steel slag aggregate has unknown durability risk, and the traditional steel slag asphalt concrete volume expansion test cannot better reflect the expansion and cracking behavior of steel slag aggregate in the asphalt concrete. In addition, the existing asphalt concrete durability evaluation method does not consider the slow hydrolysis characteristics of free calcium oxide in steel slag aggregate, and the short-term mechanical performance evaluation index cannot better reflect the long-term use durability, and there is a risk of durability. SUMMARY

[0007] The purpose of the present application is to provide a method for evaluating the durability of asphalt concrete using steel slag aggregate, which can quickly and accurately detect the stability of steel slag aggregate and the volume stability of steel slag asphalt concrete, and quantitatively detect and evaluate the long-term service mechanical durability of steel slag asphalt concrete.

[0008] To achieve the above purpose, the technical scheme is as follows:

[0009] A method for evaluating the durability of asphalt concrete using steel slag aggregate, comprising the following steps:

[0010] (1) The steel slag aggregate volume stability rapid detection method obtains a steel slag aggregate expansion and cracking and pulverization rate B; the steel slag asphalt concrete volume stability detection method obtains a circular section specimen surface damage index Y; the steel slag asphalt concrete relative strength attenuation detection method obtains a specimen relative splitting strength attenuation index S; the steel slag asphalt concrete relative fatigue life attenuation detection method obtains a specimen relative fatigue life attenuation index T;

[0011] (2) The steel slag asphalt concrete durability condition comprehensive evaluation index M is calculated;

[0012]

[0013] Wherein: M is the steel slag asphalt concrete durability condition evaluation index; a is the weight of the steel slag aggregate expansion and cracking and pulverization rate B, and is 0.15; b is the weight of the steel slag asphalt concrete circular section specimen surface damage index Y, and is 0.3; c is the weight of the steel slag asphalt concrete relative splitting strength attenuation index S, and is 0.35; d is the weight of the steel slag asphalt concrete relative fatigue life attenuation index T, and is 0.2;

[0014] (3) The steel slag asphalt concrete durability condition comprehensive evaluation index M is between 0-0.8, indicating that the steel slag asphalt concrete durability is excellent; the index M is between 0.8-1.3, indicating that the steel slag asphalt concrete durability is good; the index M is between 1.3-1.5, indicating that the steel slag asphalt concrete durability is medium; and the index M>1.5, indicating that the steel slag asphalt concrete durability is very poor

[0015] According to the above scheme, the steel slag aggregate volume stability rapid detection method comprises the following steps:

[0016] (1) Single particle size steel slag aggregates are obtained by screening with a standard square hole screen, such as 2.36mm-4.75mm particle size, 4.75mm-9.5mm particle size, 9.5mm-13.2mm particle size and 13.2mm-16mm particle size;

[0017] (2) The same specification and particle size steel slag aggregates (300-1000) are evenly placed on a steaming tray, and are placed in a steam pressure cooker for steam pressure, the working temperature of the steam pressure cooker is 126-128℃, the working pressure is 0.14-0.16MPa, and the total steam pressure time is not less than 12 hours;

[0018] (3) The steel slag aggregate expansion and cracking and pulverization rate B calculation formula is as follows:

[0019] B=m / n x 100

[0020] Wherein: B is the expansion and cracking and pulverization rate (%); m is the total number of steel slag particles that expand and crack or pulverize (pieces); and n is the total number of steel slag particles (pieces).

[0021] According to the above scheme, the steel slag asphalt concrete volume stability detection method comprises the following steps:

[0022] (1) Steel slag asphalt concrete test piece preparation: Marshall compaction method or rotary compaction forming method is used to make Marshall test pieces with a size of diameter 101.6 mm x height 63.5 mm or rotary compaction test pieces with a size of diameter 150 mm x height 115 mm, which are cooled at room temperature for 24 h and then demolded;

[0023] (2) Circular slice preparation: each end of the height of the Marshall test piece is cut by 5 mm, and then the middle is cut to obtain a circular slice with a size of diameter 101.6 mm x height 25 mm; or each end of the height of the rotary compaction test piece is cut by 5 mm, and then the middle is cut to obtain a circular slice with a size of diameter 150 mm x height 25 mm;

[0024] (3) Long-term high-temperature immersion of the circular slice test piece: the circular slice test piece (not less than 6 in one group) is immersed in a 60℃ constant-temperature water tank for not less than 14 days, and then the number and area of steel slag particle bulging or pulverization on the surface of the circular slice, and the number and length, width of cracks generated on the surface are measured;

[0025] (4) Calculation of the surface damage index Y of the circular slice test piece: the surface damage index Y is the sum of the crack area and the particle bulging and pulverization area divided by the detection area, and the calculation formula is as follows:

[0026] Y = (0.6 x L1 x 10 + 1.0 x L2 x 10 + 0.8 x S1 + 1.0 x S2) / S x 100

[0027] Wherein: Y is the surface damage index of the circular slice test piece (%); L1 is the length of the slight crack (mm); L2 is the length of the severe crack (mm); S1 is the area of the slight bulging and pulverization (mm 2 ); S2 is the area of the severe bulging and pulverization (mm 2 ); S is the area of the circular slice test piece (mm 2 );

[0028] Wherein the crack area is calculated by multiplying the crack length by the influence width (10 mm); the slight crack is a main crack with a width ≤1.0 mm, and the slight crack area should be multiplied by the artificial coefficient 0.6 when calculated; the severe crack is a main crack with a width >1.0 mm, and the severe crack area should be multiplied by the artificial coefficient 1.0 when calculated; the steel slag particle bulging and pulverization area <100 mm 2 is slight damage, and the slight bulging and pulverization area should be multiplied by the artificial coefficient 0.8 when calculated; the steel slag particle bulging and pulverization area ≥100 mm 2 is severe damage, and the severe bulging and pulverization area should be multiplied by the artificial coefficient 1.0 when calculated.

[0029] According to the above scheme, the relative strength attenuation detection method of the steel slag asphalt concrete after immersion in water comprises the following steps:

[0030] (1) Steel slag aggregate asphalt concrete test piece preparation: using steel slag aggregate and Marshall compaction method to produce two groups of Marshall test pieces with a size of 101.6mm in diameter and 63.5mm in height, and the test pieces are demolded after being cooled at room temperature for 24h; one group of Marshall test pieces is immersed in a 60℃ constant temperature water tank for not less than 14 days;

[0031] (2) Natural aggregate asphalt concrete test piece preparation: using natural aggregate and Marshall compaction method to produce two groups of Marshall test pieces with a size of 101.6mm in diameter and 63.5mm in height, and the test pieces are demolded after being cooled at room temperature for 24h; one group of Marshall test pieces is immersed in a 60℃ constant temperature water tank for not less than 14 days;

[0032] (3) Non-immersion splitting strength test: the non-immersed Marshall test pieces are placed in a 15℃-10.5℃ environmental incubator for incubation treatment for at least 4h, and then the splitting test is carried out at a loading rate of 50mm / min to obtain the non-immersion splitting strength;

[0033] (4) Immersion splitting strength test: the immersed Marshall test pieces are cooled and then placed in a 15℃-10.5℃ environmental incubator for incubation treatment for at least 4h, and then the splitting test is carried out at a loading rate of 50mm / min to obtain the immersion splitting strength;

[0034] The splitting strength R T The calculation formula is as follows:

[0035] R T = 0.006287P T / h

[0036] Wherein: R T —splitting strength (MPa); P T —maximum value of test load (N); h—test piece height (mm);

[0037] (5) The calculation formula of the splitting strength residual rate R is as follows:

[0038]

[0039] Wherein: R—splitting strength residual rate (%); R TX —15℃ splitting strength of the immersion group (MPa); R T0 —15℃ splitting strength of the non-immersion group (MPa);

[0040] (6) The calculation formula of the relative splitting strength attenuation index S is as follows:

[0041]

[0042] Wherein: S - the relative splitting strength attenuation index; R1 - the steel slag asphalt concrete splitting strength residual rate (%); R0 - the natural aggregate asphalt concrete splitting strength residual rate (%).

[0043] According to the above scheme, the steel slag asphalt concrete immersion fatigue life attenuation detection method comprises the following steps:

[0044] (1) Steel slag aggregate asphalt concrete specimen preparation: using steel slag aggregate and Marshall compaction method to produce two groups of Marshall specimens with a size of 101.6mm in diameter x 63.5mm in height, and the specimens are demolded after cooling at room temperature for 24h; one group of Marshall specimens is immersed in a 60℃ constant temperature water tank for not less than 14 days;

[0045] (2) Natural aggregate asphalt concrete specimen preparation: using natural aggregate and Marshall compaction method to produce two groups of Marshall specimens with a size of 101.6mm in diameter x 63.5mm in height, and the specimens are demolded after cooling at room temperature for 24h; one group of Marshall specimens is immersed in a 60℃ constant temperature water tank for not less than 14 days;

[0046] (3) Non-immersion indirect tensile fatigue test: the non-immersed Marshall specimens are placed in a 15℃10.5℃ environmental incubator for incubation treatment for at least 4h, and after incubation, a 0.5-0.8MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave, to obtain the indirect tensile fatigue life N0 of the non-immersed group;

[0047] (4) Immersion indirect tensile fatigue test: the immersed Marshall specimens are cooled and then placed in a 15℃10.5℃ environmental incubator for incubation treatment for at least 4h, and after incubation, a 0.5-0.8MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave, to obtain the indirect tensile fatigue life N of the immersed group; X

[0048] (5) The fatigue life residual rate P is calculated according to the following formula:

[0049]

[0050] Wherein: P - the fatigue life residual rate (%); N X - the 15℃ indirect tensile fatigue life (times) of the immersed group; N0 - the 15℃ indirect tensile fatigue life (times) of the non-immersed group;

[0051] (5) The relative fatigue life attenuation index T is calculated according to the following formula:

[0052]

[0053] ​Wherein: T is the relative fatigue life attenuation index; P1 is the fatigue life residual rate (%) of steel slag asphalt concrete; P0 is the fatigue life residual rate (%) of natural aggregate asphalt concrete.

[0054] The present application has the following advantages over the prior art:

[0055] The present application has the following advantages:

[0056] The present application can directly and quickly detect the expansion and cracking and pulverization rate of steel slag aggregate, which is beneficial to determine whether expansion and cracking or pulverization is the main problem of steel slag aggregate. Meanwhile, by collecting steel slag particles that have undergone expansion and cracking and pulverization for chemical composition analysis, it is helpful to understand the causes of poor volume stability of steel slag, which can guide the optimization of steel slag source treatment process. The present application can directly and quantitatively analyze the number of unstable particles in steel slag asphalt concrete that have undergone expansion and cracking and pulverization, as well as the number of cracks generated and the expansion mechanism of the test piece. Through the volume damage index of the test piece, it is helpful to understand and analyze the strength and fatigue attenuation reasons of steel slag asphalt concrete. The present application can quantitatively detect the mechanical strength and fatigue resistance attenuation law of steel slag asphalt concrete during long-term immersion, obtain the mechanical property residual rate through comparison between non-immersion and immersion tests, and propose a relative mechanical property attenuation index by taking natural asphalt concrete as a reference, so as to propose control indicators for the strength and fatigue resistance of steel slag asphalt concrete during long-term immersion. The present application comprehensively evaluates the above indicators and proposes a durability condition comprehensive evaluation index of steel slag asphalt concrete, which can quantitatively analyze the long-term durability change law of steel slag asphalt concrete. DETAILED DESCRIPTION

[0057] The following examples further illustrate the technical solutions of the present application, but are not intended to limit the scope of protection of the present application.

[0058] A method for evaluating the durability of asphalt concrete using steel slag aggregate is provided in the detailed description.

[0059] (1) The steel slag aggregate volume stability rapid detection method obtains the expansion and cracking and pulverization rate B of steel slag aggregate; the steel slag asphalt concrete volume stability detection method obtains the surface damage index Y of the circular section test piece; the relative strength attenuation detection method after immersion of steel slag asphalt concrete obtains the relative splitting strength attenuation index S of the test piece; and the relative fatigue life attenuation detection method of steel slag asphalt concrete after immersion obtains the relative fatigue life attenuation index T of the test piece.

[0060] (2) The durability condition comprehensive evaluation index M of steel slag asphalt concrete is calculated.

[0061]

[0062] M = aB + bY + cS + dT wherein: M—steel slag asphalt concrete durability condition evaluation index; a—steel slag aggregate expansion and cracking and pulverization rate B weight, take 0.15; b—steel slag asphalt concrete circular section specimen surface damage index Y weight, take 0.3; c—steel slag asphalt concrete relative splitting strength attenuation index S weight, take 0.35; d—steel slag asphalt concrete relative fatigue life attenuation index T weight, take 0.2;

[0063] (3) Steel slag asphalt concrete durability condition comprehensive evaluation index M between 0-0.8 indicates that the steel slag asphalt concrete durability is excellent; index M between 0.8-1.3 indicates that the steel slag asphalt concrete durability is good; index M between 1.3-1.5 indicates that the steel slag asphalt concrete durability is medium; index M>1.5 indicates that the steel slag asphalt concrete durability is very poor.

[0064] Specifically, the steel slag aggregate volume stability rapid detection method is as follows:

[0065] (1) Single particle size steel slag aggregate is obtained by using standard square hole screen, such as 2.36mm-4.75mm particle size, 4.75mm-9.5mm particle size, 9.5mm-13.2mm particle size and 13.2mm-16mm particle size;

[0066] (2) The same size and particle size steel slag aggregate (300-1000) is evenly placed on the steamer tray and placed in the steam pressure cooker, the working temperature of the steam pressure cooker is 126-128℃, the working pressure is 0.14-0.16MPa, and the total steam pressure time is not less than 12 hours;

[0067] (3) Steel slag aggregate expansion and cracking and pulverization rate B calculation formula is as follows:

[0068] B = m / n × 100

[0069] Wherein: B—expansion and cracking and pulverization rate (%); m—total number of steel slag particles that expand and crack or pulverize (pieces); n—total number of steel slag particles (pieces).

[0070] Specifically, the steel slag asphalt concrete volume stability detection method is as follows:

[0071] (1) Steel slag asphalt concrete specimen preparation: Marshall compaction method or rotary compaction forming method is used to make Marshall specimen with a size of diameter 101.6mm×height 63.5mm or rotary compaction specimen with a size of diameter 150mm×height 115mm, and the specimen is demolded after cooling for 24h at room temperature;

[0072] (2) Circular slice preparation: cut off 5mm from both ends of the Marshall specimen height, and then cut from the middle to obtain a circular slice with a diameter of 101.6mm x height of 25mm; or cut off 5mm from both ends of the rotary compacted specimen height, and then cut from the middle to obtain a circular slice with a diameter of 150mm x height of 25mm;

[0073] (3) Long-term high-temperature immersion of circular slice specimen: immerse the circular slice specimen (1 group not less than 6) in a 60°C constant temperature water tank for not less than 14 days, and after taking out, measure the number and area of the surface steel slag particle bulging or powdering, and the number and length, width of the cracks generated on the surface;

[0074] (4) Calculation of surface damage index Y of circular slice specimen: the surface damage index Y is the sum of the crack area and the particle bulging and powdering area divided by the detection area, and the calculation formula is as follows:

[0075] Y = (0.6 x L1 x 10 + 1.0 x L2 x 10 + 0.8 x S1 + 1.0 x S2) / S x 100

[0076] Wherein: Y—surface damage index of circular slice specimen (%); L1—length of slight cracks (mm); L2—length of severe cracks (mm); S1—area of slight bulging and powdering (mm 2 ); S2—area of severe bulging and powdering (mm 2 ); S—area of circular slice specimen (mm 2 );

[0077] Wherein the crack area is calculated by multiplying the crack length by the influence width (10mm); the slight crack is a main crack with a width of ≤1.0mm, and when calculating the area of slight cracks, the artificial coefficient 0.6 should be multiplied; the severe crack is a main crack with a width of >1.0mm, and when calculating the area of severe cracks, the artificial coefficient 1.0 should be multiplied; the steel slag particle bulging and powdering area <100mm 2 is slight damage, and when calculating the area of slight bulging and powdering, the artificial coefficient 0.8 should be multiplied; the steel slag particle bulging and powdering area ≥100mm 2 is severe damage, and when calculating the area of severe bulging and powdering, the artificial coefficient 1.0 should be multiplied.

[0078] Specifically, the relative strength attenuation detection method of steel slag asphalt concrete after immersion is as follows:

[0079] (1) Steel slag aggregate asphalt concrete specimen preparation: use steel slag aggregate and Marshall compaction method to prepare Marshall specimens with a size of diameter 101.6mm x height 63.5mm, 2 groups of 6 each, and the specimens are demolded after cooling at room temperature for 24h; part of the Marshall specimens are immersed in a 60°C constant temperature water tank for not less than 14 days;

[0080] (2) Natural aggregate asphalt concrete specimen preparation: two groups of Marshall specimens with a diameter of 101.6 mm and a height of 63.5 mm are prepared by using natural aggregate and Marshall compaction method, and the specimens are demolded after being cooled at room temperature for 24 hours; one group of Marshall specimens is soaked in a 60°C constant temperature water tank for not less than 14 days;

[0081] (3) Non-soaked splitting strength test: the non-soaked Marshall specimen is placed in a 15°C-10.5°C environmental incubator for incubation treatment for at least 4 hours, and then the splitting test is performed at a loading rate of 50 mm / min to obtain the non-soaked splitting strength;

[0082] (4) Soaked splitting strength test: the soaked Marshall specimen is cooled and then placed in a 15°C-10.5°C environmental incubator for incubation treatment for at least 4 hours, and then the splitting test is performed at a loading rate of 50 mm / min to obtain the soaked splitting strength;

[0083] The splitting strength R T The calculation formula is as follows:

[0084] R T = 0.006287P T / h

[0085] Wherein: R T —splitting strength (MPa); P T —maximum value of test load (N); h—specimen height (mm);

[0086] (5) The calculation formula of the splitting strength residual rate R is as follows:

[0087]

[0088] Wherein: R—splitting strength residual rate (%); R TX —15°C splitting strength of the soaked group (MPa); R T0 —15°C splitting strength of the non-soaked group (MPa);

[0089] (6) The calculation formula of the relative splitting strength attenuation index S is as follows:

[0090]

[0091] Wherein: S—relative splitting strength attenuation index; R1—splitting strength residual rate of the steel slag asphalt concrete (%); R0—splitting strength residual rate of the natural aggregate asphalt concrete (%).

[0092] Specifically, the relative fatigue life attenuation detection method of the steel slag asphalt concrete after soaking is as follows:

[0093] (1) Steel slag aggregate asphalt concrete specimen preparation: using steel slag aggregate and Marshall compaction method to make Marshall specimen with the size of 101.6mm in diameter x 63.5mm in height, 2 groups, 3 specimens in each group, the specimen is cooled at room temperature for 24h and then demolded; part of the Marshall specimen is soaked in a 60℃ constant temperature water tank for not less than 14 days;

[0094] (2) Natural aggregate asphalt concrete specimen preparation: using natural aggregate and Marshall compaction method to make Marshall specimen with the size of 101.6mm in diameter x 63.5mm in height, 2 groups, the specimen is cooled at room temperature for 24h and then demolded; one group of Marshall specimen is soaked in a 60℃ constant temperature water tank for not less than 14 days;

[0095] (3) Non-soaking indirect tensile fatigue test: the non-soaking Marshall specimen is placed in a 15℃10.5℃ environmental incubator for incubation treatment for at least 4h, after incubation, 0.5-0.8MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave, to obtain the indirect tensile fatigue life N0of the non-soaking group;

[0096] (4) Soaking indirect tensile fatigue test: the soaked Marshall specimen is cooled and then placed in a 15℃10.5℃ environmental incubator for incubation treatment for at least 4h, after incubation, 0.5-0.8MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave, to obtain the indirect tensile fatigue life N of the soaking group; X ;

[0097] (5) The fatigue life residual rate P is calculated according to the following formula:

[0098]

[0099] Wherein: P—fatigue life residual rate (%); N X —15℃ indirect tensile fatigue life (times) of the soaking group; N0—15℃ indirect tensile fatigue life (times) of the non-soaking group;

[0100] (6) The relative fatigue life attenuation index T is calculated according to the following formula:

[0101]

[0102] Wherein: T—relative fatigue life attenuation index; P1—fatigue life residual rate (%) of the steel slag asphalt concrete; P0—fatigue life residual rate (%) of the natural aggregate asphalt concrete.

[0103] Example 1:

[0104] Evaluation of the durability of the asphalt concrete using Wuyang steel slag aggregate:

[0105] 1. A rapid detection method for volume stability of Wuyang steel slag aggregate, comprising the steps of:

[0106] (1) Single particle size steel slag aggregate preparation: the steel slag aggregate is sieved by a standard square hole sieve for preparation, and steel slag aggregate with a particle size of 9.5 mm to 13.2 mm is obtained by sieving and grading;

[0107] (2) Steel slag aggregate placement: the single particle size steel slag aggregate (300) is uniformly placed on a steaming tray, and the gap between each particle is not less than 1 cm;

[0108] (3) Autoclaved steel slag aggregate: the working temperature (126℃) and the working pressure (0.14MPa) of the autoclave are set, and 6 steel slag particles are taken out after 12 hours of autoclaving for detection of the expansion, cracking and pulverization rate of the steel slag aggregate;

[0109] (4) Calculation of the expansion, cracking and pulverization rate of the steel slag aggregate: the expansion, cracking and pulverization rate B of the Wuyang steel slag aggregate is calculated to be 2%.

[0110] 2. A detection method for volume stability of Wuyang steel slag asphalt concrete, comprising the steps of:

[0111] (1) Preparation of Wuyang steel slag asphalt concrete test piece: the asphalt mixture mixing ratio is selected, the corresponding steel slag aggregate, filler and asphalt are weighed to prepare the steel slag asphalt mixture, the Marshall compaction method is used to make standard test pieces with a diameter of 101.6 mm and a height of 63.5 mm, and the test pieces are demolded after being cooled at room temperature for 24 hours;

[0112] (2) Preparation of circular section: each end of the Marshall standard test piece is cut by 5 mm, and a circular section with a thickness of 25 mm is obtained by cutting in the middle;

[0113] (3) Long-term high-temperature water immersion test: the circular section test piece is immersed in a 60℃ constant temperature water tank for 14 days, and then taken out, the expansion, cracking and pulverization number of the steel slag particles on the surface of the circular section is 0, the expansion, cracking and pulverization area is 0mm 2 , the number of cracks on the surface of the section is 0, the length of the cracks is 0mm, and the width of the cracks is 0mm;

[0114] (4) The surface damage index Y of the circular section test piece is calculated to be 0.

[0115] 3. A detection method for relative strength attenuation of Wuyang steel slag asphalt concrete after immersion, comprising the steps of:

[0116] (1) Steel slag aggregate asphalt concrete test piece preparation: the steel slag aggregate asphalt mixture is prepared according to the selected asphalt mixture mixing ratio, the corresponding Wuyang steel slag aggregate, filler and asphalt are weighed, and the Marshall compaction method is used to make standard test pieces, 2 groups, 6 test pieces in each group, the test pieces are demolded after being cooled at room temperature for 24 hours; one group is subjected to non-immersion test, and one group is immersed in a 60℃ constant temperature water tank for 14 days and then taken out for splitting strength test;

[0117] (2) Steel slag aggregate asphalt concrete non-immersed splitting strength test: 1 group of non-immersed Marshall test pieces is placed in a 15℃±0.5℃ environmental incubator for incubation treatment of the Marshall test pieces for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-immersed splitting strength of 1.983MPa;

[0118] (3) Steel slag aggregate asphalt concrete immersed splitting strength test: 1 group of immersed Marshall test pieces is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environmental incubator for incubation treatment of the Marshall test pieces for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-immersed splitting strength of 1.610MPa;

[0119] (4) Steel slag aggregate asphalt concrete splitting strength residual rate calculation: the 14-day immersed splitting strength residual rate R of Wuyang steel slag aggregate asphalt concrete is calculated to be 81.2%;

[0120] (5) Basalt aggregate asphalt concrete test piece preparation: according to the selected asphalt mixture mixing ratio, the corresponding basalt aggregate, filler and asphalt are weighed to prepare natural aggregate asphalt mixture, and standard test pieces are prepared by Marshall compaction method, 2 groups of 6 each, and the test pieces are demolded after cooling at room temperature for 24h; 1 group is used for non-immersed test, and 1 group is immersed in a 60℃ constant temperature water tank for 14 days and then taken out for splitting strength test;

[0121] (6) Basalt aggregate asphalt concrete non-immersed splitting strength test: 1 group of non-immersed Marshall test pieces is placed in a 15℃±0.5℃ environmental incubator for incubation treatment of the Marshall test pieces for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-immersed splitting strength of 1.954MPa;

[0122] (7) Basalt aggregate asphalt concrete immersed splitting strength test: 1 group of immersed Marshall test pieces is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environmental incubator for incubation treatment of the Marshall test pieces for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-immersed splitting strength of 1.652MPa;

[0123] (8) Basalt aggregate asphalt concrete splitting strength residual rate calculation: the 14-day immersed splitting strength residual rate R of basalt aggregate asphalt concrete is calculated to be 84.6%;

[0124] (9) The relative splitting strength attenuation index S of Wuyang steel slag asphalt concrete is calculated: the relative splitting strength attenuation index of steel slag aggregate is 1.2.

[0125] 4. A method for detecting the relative fatigue life attenuation of Wuyang steel slag asphalt concrete after immersion, comprising the steps of:

[0126] (1) Preparation of Wuyang steel slag asphalt concrete test pieces: according to the above selected asphalt mixture mixing ratio, the corresponding Wuyang steel slag aggregate, filler and asphalt are weighed to prepare steel slag aggregate asphalt mixture, and two groups of standard test pieces are prepared by using the Marshall compaction method, three in each group, and the test pieces are cooled at room temperature for 24 hours before demolding; one group is used for non-immersion control test, and one group is immersed in a 60°C constant temperature water tank for 14 days for indirect tensile fatigue test;

[0127] (2) Non-immersion indirect tensile fatigue test of Wuyang steel slag asphalt concrete: the non-immersion group of Marshall test pieces is placed in a 15°C±0.5°C environmental incubator to incubate the Marshall test pieces for at least 4 hours to make the test piece temperature reach the required test temperature. After incubation, load 0.6 MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5 Hz, and the stress waveform is half-sine wave. Through the test, the non-immersion indirect tensile fatigue life N0 of Wuyang steel slag aggregate asphalt concrete is 14556 times;

[0128] (3) Wuyang steel slag asphalt concrete immersion indirect tensile fatigue test: the immersion group of Marshall test pieces is taken out and cooled at room temperature for 4 hours, and then placed in a 15°C±0.5°C environmental incubator to incubate the Marshall test pieces for at least 4 hours to make the test piece temperature reach the required test temperature. After incubation, load 0.6 MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5 Hz, and the stress waveform is half-sine wave. Through the test, the 14-day immersion indirect tensile fatigue life N X of Wuyang steel slag aggregate asphalt concrete is 11445 times;

[0129] (4) Calculation of the fatigue life residual rate P of Wuyang steel slag asphalt concrete: the ratio of the immersion indirect tensile fatigue life N X and the non-immersion indirect tensile fatigue life N0 is used to calculate the fatigue life residual rate P of Wuyang steel slag aggregate asphalt concrete in 14 days, which is 78.6%;

[0130] (5) Preparation of basalt aggregate asphalt concrete test pieces: according to the above selected asphalt mixture mixing ratio, the corresponding basalt aggregate, filler and asphalt are weighed to prepare steel slag aggregate asphalt mixture, and two groups of standard test pieces are prepared by using the Marshall compaction method, three in each group, and the test pieces are cooled at room temperature for 24 hours before demolding; one group is used for non-immersion control test, and one group is immersed in a 60°C constant temperature water tank for 14 days for indirect tensile fatigue test;

[0131] (6) Basalt aggregate asphalt concrete non-immersion indirect tensile fatigue test: the non-immersion group Marshall test piece is placed in a 15℃±0.5℃ environment incubator for incubation treatment of the Marshall test piece for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, load 0.6MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. Through the test, the non-immersion indirect tensile fatigue life N0 of basalt aggregate asphalt concrete is 16416 times;

[0132] (7) Basalt aggregate asphalt concrete immersion indirect tensile fatigue test: the immersion group Marshall test piece is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environment incubator for incubation treatment of the Marshall test piece for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, load 0.6MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. Through the test, the 14-day immersion indirect tensile fatigue life N X of basalt aggregate asphalt concrete is 13496 times;

[0133] (8) Basalt aggregate asphalt concrete fatigue life residual rate P calculation: the ratio of the immersion indirect tensile fatigue life N X and the non-immersion indirect tensile fatigue life N0, the fatigue life residual rate P of basalt aggregate asphalt concrete in 14 days is calculated as 82.2%;

[0134] (9) Wuyang steel slag asphalt concrete relative fatigue life attenuation index T calculation: the relative fatigue life attenuation index of steel slag aggregate is 1.2.

[0135] 5、Steel slag asphalt concrete durability condition comprehensive evaluation, including steps:

[0136] The comprehensive evaluation index M of Wuyang steel slag asphalt concrete durability condition is calculated by formula as 0.69; in the range of 0-0.8, the durability is excellent.

[0137] Example 2:

[0138] Evaluation of the durability of asphalt concrete using Xinyang steel slag aggregate:

[0139] 1、Xinyang steel slag aggregate volume stability rapid detection method, including steps:

[0140] (1) Single particle size steel slag aggregate preparation: the steel slag aggregate is sieved with a standard square hole sieve for preparation, and the steel slag aggregate with a particle size of 4.75mm-9.5mm is obtained by sieving classification;

[0141] (2) Steel slag aggregate placement: evenly place the single particle size steel slag aggregate (600) on a steamer tray, and the gap between each particle is not less than 1cm;

[0142] (3) Autoclaved steel slag aggregate: Set the working temperature (126℃) and working pressure (0.14MPa) of the autoclave. After 12 hours of autoclaving, 108 expanded and cracked steel slag particles were obtained;

[0143] (4) Calculate the expansion and cracking rate of the steel slag aggregate: the expansion and cracking rate B of the Xinyang steel slag aggregate was 18%.

[0144] 2. The method for detecting the volume stability of Xinyang steel slag asphalt concrete, comprising the steps of:

[0145] (1) Preparation of Xinyang steel slag asphalt concrete test piece: select the asphalt mixture mix ratio, weigh the corresponding steel slag aggregate, filler and asphalt to prepare the steel slag asphalt mixture, and use the Marshall compaction method to prepare standard test pieces with a diameter of 101.6mm and a height of 63.5mm. After cooling at room temperature for 24 hours, the test pieces are demolded;

[0146] (2) Preparation of circular section: cut off 5mm from each end of the Marshall standard test piece, and then cut it in half to obtain a circular section with a thickness of 25mm;

[0147] (3) Long-term high-temperature immersion test: immerse the circular section test piece in a 60℃ constant-temperature water tank for 14 days, then take it out, and detect the number of expanded and cracked steel slag particles on the surface of the circular section, which is 15, the light expansion and cracking area is 455mm 2 , the heavy expansion and cracking area is 900mm 2 , the number of cracks on the surface of the section is 5, the length of the light crack is 45mm, and the length of the heavy crack is 48mm;

[0148] (4) Calculate the surface damage index Y of the circular section test piece, which is 24.9%.

[0149] 3. The method for detecting the relative strength attenuation of Xinyang steel slag asphalt concrete after immersion, comprising the steps of:

[0150] (1) Preparation of steel slag aggregate asphalt concrete test piece: weigh the corresponding Xinyang steel slag aggregate, filler and asphalt to prepare the steel slag aggregate asphalt mixture according to the selected asphalt mixture mix ratio, and use the Marshall compaction method to prepare standard test pieces, 2 groups, each group with 6 test pieces. After cooling at room temperature for 24 hours, the test pieces are demolded; one group is used for non-immersion test, and the other group is immersed in a 60℃ constant-temperature water tank for 14 days and then taken out for splitting strength test;

[0151] (2) Non-immersion splitting strength test of steel slag aggregate asphalt concrete: place the non-immersed group of Marshall test pieces in a 15℃±0.5℃ environmental incubator for at least 4 hours to heat treat the Marshall test pieces, so that the temperature of the test pieces reaches the required test temperature. After the heat treatment is completed, perform the splitting test at a loading rate of 50mm / min. Take the average value of 6 test pieces in each group to obtain the non-immersion splitting strength of 1.969MPa;

[0152] (3) Steel slag aggregate asphalt concrete water immersion splitting strength test: The water immersed 1 group of Marshall test pieces is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environment incubator for Marshall test piece incubation treatment for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-water immersion splitting strength of 1.262MPa;

[0153] (4) Steel slag aggregate asphalt concrete splitting strength residual rate calculation: The water immersion splitting strength residual rate R of Xinyang steel slag aggregate asphalt concrete after 14 days is calculated to be 64.1%;

[0154] (5) Basalt aggregate asphalt concrete test piece preparation: The corresponding basalt aggregate, filler and asphalt are weighed according to the selected asphalt mixture mixing ratio to prepare natural aggregate asphalt mixture, and standard test pieces are prepared by Marshall compaction method, 2 groups, 6 in each group, and the test pieces are demolded after cooling at room temperature for 24h; 1 group is used for non-water immersion test, and 1 group is immersed in a 60℃ constant temperature water tank for 14 days and then taken out for splitting strength test;

[0155] (6) Basalt aggregate asphalt concrete non-water immersion splitting strength test: The non-water immersed 1 group of Marshall test pieces is placed in a 15℃±0.5℃ environment incubator for Marshall test piece incubation treatment for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-water immersion splitting strength of 1.954MPa;

[0156] (7) Basalt aggregate asphalt concrete water immersion splitting strength test: The water immersed 1 group of Marshall test pieces is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environment incubator for Marshall test piece incubation treatment for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-water immersion splitting strength of 1.652MPa;

[0157] (8) Basalt aggregate asphalt concrete splitting strength residual rate calculation: The water immersion splitting strength residual rate R of basalt aggregate asphalt concrete after 14 days is calculated to be 84.6%;

[0158] (9) Xinyang steel slag asphalt concrete relative splitting strength attenuation index S calculation: The relative splitting strength attenuation index of steel slag aggregate is calculated to be 2.3.

[0159] 4. A method for detecting the relative fatigue life attenuation of Xinyang steel slag asphalt concrete after water immersion, comprising the steps of:

[0160] (1) Xinyang steel slag asphalt concrete specimen preparation: according to the selected asphalt mixture mixing ratio, the corresponding Xinyang steel slag aggregate, filler and asphalt are weighed to prepare steel slag aggregate asphalt mixture, and 2 groups of standard specimens are prepared by Marshall compaction method, 3 in each group, and the specimens are cooled at room temperature for 24 h and demolded; one group is used for non-soaking control test, and one group is soaked in a 60°C constant temperature water tank for 14 days for indirect tensile fatigue test;

[0161] (2) Xinyang steel slag asphalt concrete non-soaking indirect tensile fatigue test: the non-soaking group Marshall specimen is placed in a 15°C±0.5°C environment incubator for at least 4 h to heat treat the Marshall specimen, so that the specimen temperature reaches the required test temperature. After incubation, load 0.6 MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5 Hz, and the stress waveform is half-sine wave. Through the test, the non-soaking indirect tensile fatigue life N0 of Xinyang steel slag aggregate asphalt concrete is 14904 times;

[0162] (3) Xinyang steel slag asphalt concrete soaking indirect tensile fatigue test: the soaked group Marshall specimen is taken out and cooled at room temperature for 4 h, and then placed in a 15°C±0.5°C environment incubator for at least 4 h to heat treat the Marshall specimen, so that the specimen temperature reaches the required test temperature. After incubation, load 0.6 MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5 Hz, and the stress waveform is half-sine wave. Through the test, the 14-day soaking indirect tensile fatigue life N X of Xinyang steel slag aggregate asphalt concrete is 6278 times;

[0163] (4) Xinyang steel slag asphalt concrete fatigue life residual rate P calculation: the ratio of the soaking indirect tensile fatigue life N X and the non-soaking indirect tensile fatigue life N0 is used to calculate the 14-day fatigue life residual rate P of Xinyang steel slag aggregate asphalt concrete, which is 42.1%;

[0164] (5) Basalt aggregate asphalt concrete specimen preparation: according to the selected asphalt mixture mixing ratio, the corresponding basalt aggregate, filler and asphalt are weighed to prepare steel slag aggregate asphalt mixture, and 2 groups of standard specimens are prepared by Marshall compaction method, 3 in each group, and the specimens are cooled at room temperature for 24 h and demolded; one group is used for non-soaking control test, and one group is soaked in a 60°C constant temperature water tank for 14 days for indirect tensile fatigue test;

[0165] (6) Basalt aggregate asphalt concrete non-immersion indirect tensile fatigue test: the non-immersion group Marshall specimen is placed in 15℃±0.5℃ environment incubator to incubate Marshall specimen for at least 4h, so that the specimen temperature reaches the required temperature. After incubation, 0.6MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. Through the test, the non-immersion indirect tensile fatigue life N0 of basalt aggregate asphalt concrete is 16416 times;

[0166] (7) Basalt aggregate asphalt concrete immersion indirect tensile fatigue test: the immersion group Marshall specimen is taken out and cooled at room temperature for 4h, and then placed in 15℃±0.5℃ environment incubator to incubate Marshall specimen for at least 4h, so that the specimen temperature reaches the required temperature. After incubation, 0.6MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. Through the test, the 14-day immersion indirect tensile fatigue life N of basalt aggregate asphalt concrete is 13496 times; X

[0167] (8) Basalt aggregate asphalt concrete fatigue life residual rate P calculation: the ratio of the immersion indirect tensile fatigue life N X and the non-immersion indirect tensile fatigue life N0, the fatigue life residual rate P of basalt aggregate asphalt concrete in 14 days is calculated as 82.2%;

[0168] (9) Xinyang steel slag asphalt concrete relative fatigue life attenuation index T calculation: the relative fatigue life attenuation index of steel slag aggregate is calculated as 3.3.

[0169] 5、Steel slag asphalt concrete durability condition comprehensive evaluation, including steps:

[0170] The comprehensive evaluation index M of Xinyang steel slag asphalt concrete durability condition is calculated as 2.23 by formula; it is out of the 1.5 limit, and its durability is very poor.

[0171] Example 3:

[0172] Evaluation of Jianlong steel slag aggregate asphalt concrete durability:

[0173] 1、Jianlong steel slag aggregate volume stability rapid detection method, including steps:

[0174] (1) Single particle size steel slag aggregate preparation: the steel slag aggregate is sieved with a standard square hole sieve for use, and the steel slag aggregate with a particle size of 4.75mm-9.5mm is obtained by sieving classification;

[0175] (2) Steel slag aggregate placement: the single particle size steel slag aggregate (900) is evenly placed on the steamer tray, and the gap between each particle is not less than 1cm; ​

[0176] (3) Autoclaved steel slag aggregate: Set the working temperature (126℃) and working pressure (0.14MPa) of the autoclave. After 12 hours of autoclaving, 99 steel slag particles were found to have expanded, cracked and pulverized;

[0177] (4) Calculate the expansion, cracking and pulverization rate of the steel slag aggregate: The expansion, cracking and pulverization rate B of the Jianlong steel slag aggregate was calculated to be 11%.

[0178] 2. The method for detecting the volume stability of Jianlong steel slag asphalt concrete, comprising the steps of:

[0179] (1) Preparation of Jianlong steel slag asphalt concrete test piece: Select the asphalt mixture mix ratio, weigh the corresponding steel slag aggregate, filler and asphalt to prepare the steel slag asphalt mixture, and use the Marshall compaction method to make standard test pieces with a diameter of 101.6mm and a height of 63.5mm. After cooling at room temperature for 24 hours, the test pieces are demolded;

[0180] (2) Preparation of circular section: Cut off 5mm from both ends of the Marshall standard test piece, and then cut it in half to obtain a circular section with a thickness of 25mm;

[0181] (3) Long-term high-temperature immersion test: After immersing the circular section test piece in a 60℃ constant temperature water tank for 14 days, 6 steel slag particles on the surface of the circular section were found to have expanded, cracked and pulverized, the light expansion, cracking and pulverization area was 160mm 2 , the heavy expansion, cracking and pulverization area was 360mm 2 , the number of cracks on the surface of the section was 6, the length of the light crack was 38mm, and the length of the heavy crack was 72mm;

[0182] (4) Calculate the surface damage index Y of the circular section test piece to be 17.7%.

[0183] 3. The method for detecting the relative strength attenuation of Jianlong steel slag asphalt concrete after immersion, comprising the steps of:

[0184] (1) Preparation of steel slag aggregate asphalt concrete test piece: Weigh the corresponding Jianlong steel slag aggregate, filler and asphalt to prepare the steel slag aggregate asphalt mixture according to the selected asphalt mixture mix ratio, and use the Marshall compaction method to make standard test pieces in two groups, each group containing 6 test pieces. After cooling at room temperature for 24 hours, the test pieces are demolded. One group is used for non-immersion test, and the other group is immersed in a 60℃ constant temperature water tank for 14 days and then taken out for splitting strength test;

[0185] (2) Non-immersion splitting strength test of steel slag aggregate asphalt concrete: Place the non-immersion group of Marshall test pieces in a 15℃±0.5℃ environmental incubator for at least 4 hours to heat the test pieces to the required test temperature. After incubation, perform the splitting test at a loading rate of 50mm / min. Take the average value of 6 test pieces in each group to obtain the non-immersion splitting strength of 2.246MPa.

[0186] (3) Steel slag aggregate asphalt concrete water immersion splitting strength test: The water immersed 1 group of Marshall test pieces is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environment incubator for Marshall test piece incubation treatment for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-water immersion splitting strength of 1.669MPa;

[0187] (4) Steel slag aggregate asphalt concrete splitting strength residual rate calculation: The 14-day water immersion splitting strength residual rate R of Jianlong steel slag aggregate asphalt concrete is calculated to be 74.3%;

[0188] (5) Limestone aggregate asphalt concrete test piece preparation: According to the selected asphalt mixture mixing ratio, limestone aggregate, filler and asphalt are weighed to prepare natural aggregate asphalt mixture, and standard test pieces are prepared by Marshall compaction method, 2 groups, 6 in each group, and the test pieces are demolded after cooling at room temperature for 24h; 1 group is used for non-water immersion test, and 1 group is immersed in a 60℃ constant temperature water tank for 14 days and then taken out for splitting strength test;

[0189] (6) Limestone aggregate asphalt concrete non-water immersion splitting strength test: The non-water immersed 1 group of Marshall test pieces is placed in a 15℃±0.5℃ environment incubator for Marshall test piece incubation treatment for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-water immersion splitting strength of 1.903MPa;

[0190] (7) Limestone aggregate asphalt concrete water immersion splitting strength test: The water immersed 1 group of Marshall test pieces is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environment incubator for Marshall test piece incubation treatment for at least 4h, so that the test piece temperature reaches the required test temperature. After incubation, the splitting test is carried out at a loading rate of 50mm / min, and the average value of 6 test pieces in each group is obtained to obtain the non-water immersion splitting strength of 1.576MPa;

[0191] (8) Limestone aggregate asphalt concrete splitting strength residual rate calculation: The 14-day water immersion splitting strength residual rate R of limestone aggregate asphalt concrete is calculated to be 82.8%;

[0192] (9) Jianlong steel slag asphalt concrete relative splitting strength attenuation index S calculation: The relative splitting strength attenuation index of steel slag aggregate is calculated to be 1.5.

[0193] 4. A method for detecting the relative fatigue life attenuation of Jianlong steel slag asphalt concrete after water immersion, comprising the steps of:

[0194] (1) Jiansheng slag asphalt concrete specimen preparation: according to the selected asphalt mixture ratio, the corresponding Jiansheng slag aggregate, filler and asphalt are weighed to prepare slag aggregate asphalt mixture, and 2 groups of standard specimens are prepared by Marshall compaction method, 3 in each group, and the specimens are cooled at room temperature for 24 h and demolded; one group is used for non-soaking control test, and one group is soaked in 60°C constant temperature water tank for 14 days for indirect tensile fatigue test;

[0195] (2) Jiansheng slag asphalt concrete non-soaking indirect tensile fatigue test: the non-soaking group Marshall specimen is placed in a 15°C±0.5°C environment incubator for at least 4h to heat the Marshall specimen to the required test temperature. After incubation, load 0.8MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. The non-soaking indirect tensile fatigue life N0 of Jiansheng slag aggregate asphalt concrete is obtained by test as 6040 times;

[0196] (3) Jiansheng slag asphalt concrete soaking indirect tensile fatigue test: the soaking group Marshall specimen is taken out and cooled at room temperature for 4h, and then placed in a 15°C±0.5°C environment incubator for at least 4h to heat the Marshall specimen to the required test temperature. After incubation, load 0.8MPa indirect tensile fatigue stress according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. The 14-day soaking indirect tensile fatigue life N of Jiansheng slag aggregate asphalt concrete is obtained by test as 3416 times; X

[0197] (4) Jiansheng slag asphalt concrete fatigue life residual rate P calculation: the ratio of the soaking indirect tensile fatigue life N and the non-soaking indirect tensile fatigue life N0 is used to calculate the 14-day fatigue life residual rate P of Jiansheng slag aggregate asphalt concrete, which is 56.6%; X

[0198] (5) Limestone aggregate asphalt concrete specimen preparation: according to the selected asphalt mixture ratio, the corresponding limestone aggregate, filler and asphalt are weighed to prepare slag aggregate asphalt mixture, and 2 groups of standard specimens are prepared by Marshall compaction method, 3 in each group, and the specimens are cooled at room temperature for 24 h and demolded; one group is used for non-soaking control test, and one group is soaked in 60°C constant temperature water tank for 14 days for indirect tensile fatigue test;

[0199] ​​(6) Non-soaked indirect tensile fatigue test of limestone aggregate asphalt concrete: the non-soaked Marshall specimen is placed in a 15℃±0.5℃ environment incubator for incubation of the Marshall specimen for at least 4h, so that the specimen temperature reaches the required test temperature. After incubation, 0.8MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. Through the test, the non-soaked indirect tensile fatigue life N0 of limestone aggregate asphalt concrete is 6141 times;

[0200] (7) Soaked indirect tensile fatigue test of limestone aggregate asphalt concrete: the soaked Marshall specimen is taken out and cooled at room temperature for 4h, and then placed in a 15℃±0.5℃ environment incubator for incubation of the Marshall specimen for at least 4h, so that the specimen temperature reaches the required test temperature. After incubation, 0.8MPa indirect tensile fatigue stress is loaded according to the stress mode, the loading frequency is 5Hz, and the stress waveform is half-sine wave. Through the test, the 14-day soaked indirect tensile fatigue life N X of limestone aggregate asphalt concrete is 4896 times;

[0201] (8) Calculation of fatigue life residual rate P of limestone aggregate asphalt concrete: the ratio of the soaked indirect tensile fatigue life N X and the non-soaked indirect tensile fatigue life N0 is used to calculate the fatigue life residual rate P of limestone aggregate asphalt concrete in 14 days, which is 79.7%;

[0202] (9) Calculation of relative fatigue life attenuation index T of Jianlong steel slag asphalt concrete: the relative fatigue life attenuation index of steel slag aggregate is calculated to be 2.1.

[0203] 5、Comprehensive evaluation of the durability status of steel slag asphalt concrete, including the steps of:

[0204] The comprehensive evaluation index M of the durability status of Jianlong steel slag asphalt concrete is calculated by formula to be 1.46; in the range of 1.3-1.5, the durability is poor.

Claims

1. A method for evaluating the durability of asphalt concrete using steel slag aggregate, characterized in that... Includes the following steps: (1) The rapid detection method for the volume stability of steel slag aggregate yields the expansion and pulverization rate B of steel slag aggregate; The surface damage index Y of circular slice specimens was obtained from the test method for the volume stability of steel slag asphalt concrete. The relative strength attenuation test method for steel slag asphalt concrete after immersion in water yields the relative splitting strength attenuation index S of the specimen. The relative fatigue life attenuation index T of steel slag asphalt concrete specimens was obtained by a water immersion test method. (2) The comprehensive evaluation index M of the durability of steel slag asphalt concrete was calculated; Where: M—Durability evaluation index of steel slag asphalt concrete; a—Weight of steel slag aggregate cracking and pulverization rate B, taken as 0.15; b—Weight of surface damage index Y of steel slag asphalt concrete circular slice specimen, taken as 0.3; c—Weight of steel slag asphalt concrete relative splitting strength attenuation index S, taken as 0.35; d—Weight of steel slag asphalt concrete relative fatigue life attenuation index T, taken as 0.

2. (3) The comprehensive evaluation index M of the durability of steel slag asphalt concrete is between 0 and 0.8, which indicates that the durability of steel slag asphalt concrete is excellent; the index M is between 0.8 and 1.3, which indicates that the durability of steel slag asphalt concrete is good; the index M is between 1.3 and 1.5, which indicates that the durability of steel slag asphalt concrete is moderate; and the index M>1.5 indicates that the durability of steel slag asphalt concrete is very poor. The method for detecting the volume stability of steel slag asphalt concrete includes the following steps: (1) Preparation of steel slag asphalt concrete specimens: Marshall specimens with a diameter of 101.6 mm × height of 63.5 mm or rotary compaction specimens with a diameter of 150 mm × height of 115 mm were prepared by Marshall compaction method or rotary compaction method. The specimens were demolded after cooling at room temperature for 24 hours. (2) Preparation of circular slices: Cut off 5 mm from both ends of the height of the Marshall specimen and then cut it in the middle to obtain a circular slice with a diameter of 101.6 mm × height of 25 mm; or cut off 5 mm from both ends of the height of the rotary compacted specimen and then cut it in the middle to obtain a circular slice with a diameter of 150 mm × height of 25 mm. (3) Long-term high-temperature immersion of circular slice specimens: Immerse the circular slice specimens in a constant temperature water tank at 60℃ for no less than 14 days. After taking them out, measure the number and area of ​​steel slag particles that have expanded or pulverized on the surface of the circular slices, as well as the number, length, and width of cracks that have been generated on the surface. (4) Calculation of surface damage index Y of circular slice specimen: The surface damage index Y is the sum of the crack area and the particle swelling and pulverization area divided by the test area. The calculation formula is as follows: + Wherein: Y - the surface damage index of the round slice specimen, %; L1 - the length of slight cracks, mm; L2 - the length of severe cracks, mm; S1 - the area of slight bulging and powdering, mm 2 ; S2 - the area of severe bulging and powdering, mm 2 ; S - the area of the round slice specimen, mm 2 ; Wherein the crack area is calculated by crack length multiplied by the influence width of 10 mm; the slight crack is the main crack width ≤1.0 mm, and the slight crack area should be multiplied by the artificial coefficient 0.6 when calculating; the severe crack is the main crack width >1.0 mm, and the severe crack area should be multiplied by the artificial coefficient 1.0 when calculating; the steel slag particle expansion and cracking powder area <100 mm 2 is slight damage, and the slight expansion and cracking powder area should be multiplied by the artificial coefficient 0.8 when calculating; the steel slag particle expansion and cracking powder area ≥100 mm 2 is severe damage, and the severe expansion and cracking powder area should be multiplied by the artificial coefficient 1.0 when calculating; The method for detecting the relative strength attenuation of steel slag asphalt concrete after immersion in water includes the following steps: (1) Preparation of steel slag aggregate asphalt concrete specimens: Two sets of Marshall specimens with a diameter of 101.6 mm × height of 63.5 mm were prepared using steel slag aggregate and Marshall compaction method. The specimens were demolded after cooling at room temperature for 24 hours. One set of Marshall specimens was immersed in a 60℃ constant temperature water tank for no less than 14 days. (2) Preparation of natural aggregate asphalt concrete specimens: Two sets of Marshall specimens with a diameter of 101.6 mm × height of 63.5 mm were prepared using natural aggregate and Marshall compaction method. The specimens were demolded after cooling at room temperature for 24 hours. One set of Marshall specimens was immersed in a 60℃ constant temperature water tank for no less than 14 days. (3) Splitting strength test: The non-water-immersed Marshall specimen was placed in an environmental heat preservation box at 15℃±0.5℃ for at least 4 hours. After the heat preservation was completed, a splitting test was carried out at a loading rate of 50mm / min to obtain the non-water-immersed splitting strength; the water-immersed Marshall specimen was cooled and then placed in an environmental heat preservation box at 15℃±0.5℃ for at least 4 hours. After the heat preservation was completed, a splitting test was carried out at a loading rate of 50mm / min to obtain the water-immersed splitting strength. The splitting strength R T The calculation formula is as follows: wherein: R T —splitting strength; P T —maximum value of the test load, N; h—height of the specimen, mm; (4) The formula for calculating the splitting strength residual rate R is as follows: ； Where: R - residual rate of splitting strength, %; R TX - immersed splitting strength; R T0 - non-immersed splitting strength; (5) The formula for calculating the relative splitting strength attenuation index S is as follows: Where: S—relative splitting strength attenuation index; R1—residual splitting strength of steel slag asphalt concrete, %; R0—residual splitting strength of natural aggregate asphalt concrete, % The method for detecting the relative fatigue life decline of steel slag asphalt concrete after immersion in water includes the following steps: (1) Preparation of steel slag aggregate asphalt concrete specimens: Two sets of Marshall specimens with a diameter of 101.6 mm × height of 63.5 mm were prepared using steel slag aggregate and Marshall compaction method. The specimens were demolded after cooling at room temperature for 24 hours. One set of Marshall specimens was immersed in a 60℃ constant temperature water tank for no less than 14 days. (2) Preparation of natural aggregate asphalt concrete specimens: Two sets of Marshall specimens with a diameter of 101.6 mm × height of 63.5 mm were prepared using natural aggregate and Marshall compaction method. The specimens were demolded after cooling at room temperature for 24 hours. One set of Marshall specimens was immersed in a 60℃ constant temperature water tank for no less than 14 days. (3) Non-immersion indirect tensile fatigue test: The non-immersion Marshall specimen was placed in an environmental heat preservation box at 15℃±0.5℃ for at least 4 hours. After the heat preservation was completed, 0.5~0.8MPa indirect tensile fatigue stress was applied according to the stress mode, the loading frequency was 5Hz, and the stress waveform was half sine wave. The indirect tensile fatigue life N0 of the non-immersion group was obtained. (4) Water immersion indirect tensile fatigue test: After cooling the water-immersed Marshall specimens, place them in an environmental insulation chamber at 15℃±0.5℃ for at least 4 hours. After the insulation is completed, apply an indirect tensile fatigue stress of 0.5~0.8MPa according to the stress mode. The loading frequency is 5Hz, and the stress waveform is a half-sine wave. The indirect tensile fatigue life N of the water-immersed group is obtained. X ; (5) The formula for calculating the fatigue life residual rate P is as follows: Where: P—fatigue life residual rate, %; N X —Indirect tensile fatigue life at 15℃ for the immersion group, times; N0—Indirect tensile fatigue life at 15℃ for the non-immersion group, times. (6) The formula for calculating the relative fatigue life decay index T is as follows: Where: T—relative fatigue life decay index; P1—fatigue life residual rate of steel slag asphalt concrete, %; P0—fatigue life residual rate of natural aggregate asphalt concrete, %.

2. The method for evaluating the durability of asphalt concrete using steel slag aggregate as described in claim 1, characterized in that... The rapid testing method for the volumetric stability of steel slag aggregate includes the following steps: (1) Steel slag aggregate of a single particle size was obtained by screening with a standard square hole screen; (2) Place steel slag aggregates of the same size evenly on a steaming tray and steam them in an autoclave. The working temperature of the autoclave is 126-128℃, the working pressure is 0.14-0.16MPa, and the total steaming time is not less than 12 hours. (3) The formula for calculating the expansion and pulverization rate B of steel slag aggregate is as follows: Where: B—expansion and pulverization rate, %; m—total number of steel slag particles that have expanded or pulverized, units; n—total number of steel slag particles, units.

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