Polyethylene concrete mix design method

Abstract

The application discloses a polyethylene concrete mix proportion design method and relates to the technical field of concrete materials; the polyethylene type is preliminarily selected based on a melting point temperature of 70-140 DEG C and a melting index of 40-200 g / 10 min, and aggregate and a flow modifier are selected; the temperature corresponding to the apparent viscosity of 450±30 Pa·s is selected as the mixing temperature of the polyethylene concrete according to the polyethylene type; the aggregate gradation range is screened, and the aggregate gradation is preferably selected; the flow modifier dosage is selected when the water stability is the best according to the preliminary polyethylene content and the selected polyethylene; the best cement-aggregate ratio is obtained by preliminary selection; the performance indexes of the polyethylene concrete are screened, the performance of the polyethylene concrete is verified according to the performance indexes, and the mix proportion of the polyethylene concrete is further optimized according to the technical requirements of the performance indexes of the polyethylene concrete.

Description

TECHNICAL FIELD

[0001] The application discloses a method and relates to the technical field of concrete materials, in particular to a polyethylene concrete mix proportion design method. BACKGROUND

[0002] Currently, plastics are mainly added into cement concrete as substitutes for fine aggregates or used as composite materials in combination with asphalt concrete. There is no perfect design method for preparing plastic concrete by taking plastics as cementitious materials. Due to the lack of a systematic design method, the types of plastics, the gradation of aggregates, the types of modifiers, the adding amounts of materials and the corresponding preparation parameters cannot be selected in a targeted manner at present, so that the plastics cannot be completely wrapped around the aggregates, the performance index parameters of the concrete are unstable, the performance of the plastic concrete is affected, and the subsequent construction and use are affected. SUMMARY

[0003] The polyethylene concrete mix proportion design method provided by the application rationally designs and selects plastics as polyethylene, rationally designs the gradation of aggregates, the adding amounts of materials and the preparation parameters, and performs performance testing, so that a systematic polyethylene concrete mix proportion design method is finally formed, and a strong reference is provided for subsequent preparation and research of polyethylene concrete.

[0004] The specific scheme provided by the application is as follows:

[0005] The application provides a polyethylene concrete mix proportion design method, and the specific steps are as follows:

[0006] Step 1: based on the melting point temperature of 70-140 DEG C and the melt index of 40-200 g / 10 min, the types of polyethylene are preliminarily selected, and the aggregates and the flow modifier are selected,

[0007] Step 2: the apparent viscosity of the polyethylene at different temperatures is tested, the apparent viscosity-temperature curve is drawn, the temperature corresponding to the apparent viscosity of 450±30 Pa·s is selected as the mixing temperature of the polyethylene concrete according to the range of the apparent viscosity of the polyethylene,

[0008] Step 3: the aggregate gradation range is screened, a certain number of gradations are initially selected in the screened aggregate gradation range, the aggregates are selected, the polyethylene adding amount is initially selected, the Marshall test piece is prepared, the Marshall stability and the flying loss index are obtained based on the Marshall stability test and the standard flying test, and the aggregate gradation is preferably selected according to the results,

[0009] Step 4: based on the selected polyethylene, the improvement effect of the flow modifier is evaluated from the water stability according to the initially selected polyethylene adding amount and the flow modifier of different dosages, the freeze-thaw splitting test, the flying test and the immersion flying test are respectively performed, the flow modifier dosage with the best water stability is selected,

[0010] Step 5: preliminary selection of the cement ratio, the cement ratio being the mass ratio of polyethylene and aggregate, preparing Marshall test pieces according to the cement ratio respectively, determining the void ratio and polyethylene saturation degree of the test pieces under different cement ratios, drawing the corresponding curves, determining the maximum value and minimum value corresponding to the cement ratio respectively according to the required range of the void ratio and polyethylene saturation degree, and taking the average of the maximum value and the minimum value respectively, and taking the average of the two average values obtained to obtain the optimal cement ratio,

[0011] Step 6: preparing polyethylene concrete Marshall test pieces based on the optimal cement ratio, screening the performance indicators of polyethylene concrete, testing the performance of polyethylene concrete according to the performance indicators, and further optimizing the mix proportion of polyethylene concrete according to the technical requirements of the performance indicators of polyethylene concrete.

[0012] Preferably, in the polyethylene concrete mix proportion design method, the low-density polyethylene is selected as the polyethylene type in the plastic concrete based on the melting point temperature of 70-140℃ and the melt index of 40-200g / 10min in step 1.

[0013] Preferably, in the polyethylene concrete mix proportion design method, the temperature of 195-215℃ corresponding to the apparent viscosity of 450±30Pa·s is selected as the mixing temperature of the low-density polyethylene concrete according to the apparent viscosity range of the low-density polyethylene in step 2.

[0014] Preferably, in the polyethylene concrete mix proportion design method, the aggregate grading range is PC-13 grading range in step 3, and the PC-13 grading range is obtained by removing the aggregate with a particle size less than 0.075mm according to the standard of SMA-13 asphalt mixture grading, and three gradings are initially selected within the PC-13 grading range.

[0015] Preferably, in the polyethylene concrete mix proportion design method, the PC-13 grading range is shown in the following table in step 3:

[0016]

[0017] Preferably, in the polyethylene concrete mix proportion design method, three gradings are initially selected within the PC-13 grading range in step 3, which are coarse type grading, medium type grading and fine type grading, wherein the coarse type grading is the upper limit of the PC-13 grading, the medium type grading is the median value of the PC-13 grading, and the fine type grading is the lower limit of the PC-13 grading,

[0018] The initial polyethylene content was selected as 5.0%-6.0%, and Marshall specimens were prepared by mixing it with coarse, medium and fine aggregates. Based on the Marshall stability and scattering loss index, the medium aggregate was selected as the preferred aggregate gradation.

[0019] Preferably, in step 4 of the polyethylene concrete mix design method, based on the selected polyethylene, according to the medium gradation and the initial polyethylene content of 5.0%-6.0%, 3%, 6%, 9% and 12% of the polyethylene mass are selected as the content of flow modifier, respectively. The flow modifier is an aliphatic polyester. Marshall specimens are prepared, and the flow modifier dosage with the best water stability is selected as 9% of the polyethylene mass.

[0020] Preferably, in step 5 of the polyethylene concrete mix design method, when initially selecting the aggregate-cement ratio, a medium-sized gradation is selected as the aggregate gradation. Using the initially selected aggregate-cement ratio as the median, 3-5 aggregate-cement ratios are taken at 0.5% intervals. Marshall specimens are prepared at the corresponding mixing temperatures. The porosity and plastic saturation of the Marshall specimens are calculated. Porosity-aggregate ratio curves and plastic saturation-aggregate ratio curves are plotted with the aggregate-cement ratio as the abscissa and porosity and plastic saturation as the ordinates, respectively.

[0021] The minimum OPC corresponding to the porosity range of 18.0%-20.0% in the porosity-aggregate ratio curve was selected. min1 And the maximum ratio of OPC to glue stone max1 Request OPC min1 and OPC max1 The average value of OPC1,

[0022] The minimum OPC (oligomeric saturation ratio) corresponding to a plastic saturation range of 35%-40% was selected from the plastic saturation-rubber-stone ratio curve. min2 And the maximum ratio of OPC to glue stone max2 Request OPC min2 and OPC max2 The average value of OPC2,

[0023] Calculate the average value of OPC1 and OPC2, and use OPC as the optimal glue-stone ratio.

[0024] Preferably, the performance indicators for screening polyethylene concrete in step 6 of the polyethylene concrete mix design method are shown in the table below:

[0025]

[0026] The advantages of this invention are:

[0027] The application provides a polyethylene concrete mix proportion design method, selects polyethylene with a melting point in the range of 70-140 DEG C and meeting a melt index of 40-200 g / 10 min as cementitious material in concrete, and selects SMA-13 asphalt mixture gradation to remove aggregate with a particle size lower than 0.075 mm to form PC-13 as aggregate, and the selected polyethylene can be polyethylene which is fully wrapped around the aggregate, and the temperature corresponding to the polyethylene with an apparent viscosity of 450+ / -30 Pa.s is selected as the mixing temperature of the polyethylene concrete, so as to avoid the influence of the rheological property of the polyethylene at high temperature on the mixing and forming property of the polyethylene concrete, and the dosage of the flow modifier is screened and the optimal cement-aggregate ratio is determined, so as to obtain the polyethylene concrete mix proportion, and the polyethylene concrete test piece prepared according to the polyethylene concrete mix proportion is screened according to the performance index, and the polyethylene concrete mix proportion is further optimized and adjusted, so as to provide strong data support for subsequent polyethylene concrete preparation and application. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a method flowchart of the application.

[0029] Figure 2 It is a void ratio-cement-aggregate ratio curve schematic diagram involved in the application.

[0030] Figure 3 It is a plastic saturation-cement-aggregate ratio curve schematic diagram involved in the application. DETAILED DESCRIPTION

[0031] The application will be further described below in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the application and implement it, but the embodiments are not used as limitations to the application.

[0032] The specific scheme provided by the application is:

[0033] The application provides a polyethylene concrete mix proportion design method, and the specific steps are as follows:

[0034] Step 1: based on the melting point temperature of 70-140 DEG C and the melt index of 40-200 g / 10 min, the polyethylene type is preliminarily selected, and aggregate and a flow modifier are selected,

[0035] Step 2: test the apparent viscosity of the polyethylene at different temperatures, draw the apparent viscosity-temperature change curve, and select the temperature corresponding to the apparent viscosity equal to 450+ / -30 Pa.s as the mixing temperature of the polyethylene concrete according to the apparent viscosity range of the polyethylene,

[0036] Step 3: screening aggregate gradation range, selecting aggregate gradation in the screened aggregate gradation range, selecting polyethylene content, preparing formed Marshall test piece, obtaining Marshall stability and flying loss index based on Marshall stability test and standard flying test, and optimizing aggregate gradation according to the results,

[0037] Step 4: based on the selected polyethylene, adding different doses of flow modifier according to the selected polyethylene content, evaluating the improvement effect of the flow modifier from the perspective of water stability, respectively performing freeze-thaw splitting test, flying test and water immersion flying test, and selecting the flow modifier dose with the best water stability,

[0038] Step 5: selecting the glue stone ratio, which is the mass ratio of polyethylene and aggregate, preparing Marshall test pieces according to the glue stone ratio, measuring the void ratio and polyethylene saturation degree of the test pieces under different glue stone ratios, drawing corresponding curves, determining the maximum value and minimum value corresponding to the glue stone ratio according to the required range of the void ratio and polyethylene saturation degree, respectively, and taking the average of the maximum value and the minimum value, and then taking the average of the two average values to obtain the best glue stone ratio,

[0039] Step 6: preparing polyethylene concrete Marshall test pieces based on the best glue stone ratio, screening the performance index of polyethylene concrete, testing the performance of polyethylene concrete according to the performance index, and further optimizing the mix proportion of polyethylene concrete according to the technical requirements of the performance index of polyethylene concrete.

[0040] The method of the present application selects materials including PE, aggregate and flow modifier, determines the test temperature through the apparent viscosity test, selects the aggregate gradation within the PC-13 gradation range, selects the design gradation, initially selects the glue stone ratio, mixes the concrete and prepares the Marshall test piece, can test the relative density of bulk volume by the volume method, tests the maximum relative density by the vacuum method, calculates and judges the void ratio and PE saturation degree, determines the best glue stone ratio through the glue stone ratio range, performs the Marshall stability test and the standard flying test, compares with the technical requirements of the performance index, and finally prepares the concrete test piece according to the design gradation and the best glue stone ratio, tests the high-temperature performance, low-temperature performance and water stability performance, and completes the optimization of the mix proportion design of PE concrete.

[0041] In specific applications, in some embodiments of the method of the present application, based on the technical solution of the method of the present application, the following process can be referred to:

[0042] Step 1: selecting low-density polyethylene (LDPE) as the type of polyethylene in plastic concrete according to the melting point temperature of 70-140 DEG C and the melt index, selecting basalt or diabase as the aggregate used in PE concrete, and selecting high-molecular-weight saturated aliphatic polyester as the flow modifier. Table 1 shows the melting point and melt index of low-density polyethylene.

[0043] Table 1

[0044]

[0045] Step 2: The apparent viscosity of the plastic can be measured by a rotary rheometer, and the temperature corresponding to the apparent viscosity of 450±30 Pa·s in the range of the apparent viscosity of low-density polyethylene is selected as the mixing temperature of the low-density polyethylene concrete, and further preferably the mixing temperature of the low-density polyethylene concrete is 200℃ corresponding to the apparent viscosity of 453.5 Pa·s of the LDPE melt, and the mixing time of the LDPE concrete can be 210 s, and preferably the mixing temperature is reduced by 5℃ as the compaction temperature of the concrete test piece.

[0046] Step 3: The aggregate gradation range is PC-13 gradation range, which is obtained by removing the aggregate with a particle size less than 0.075 mm according to the standard of SMA-13 asphalt mixture gradation, and three gradations are initially selected in the PC-13 gradation range.

[0047] Preferably, the PC-13 gradation range is as shown in the following table:

[0048]

[0049] Preferably, three gradations are initially selected in the PC-13 gradation range in step 3, which are coarse gradation, medium gradation and fine gradation, wherein the coarse gradation is close to the upper limit of the PC-13 gradation, the medium gradation is close to the median value of the PC-13 gradation, and the fine gradation is close to the lower limit of the PC-13 gradation,

[0050] The initial polyethylene content is 5.0%-6.0%, preferably 5%, and the coarse gradation, medium gradation and fine gradation are prepared into Marshall test pieces, and the preparation process refers to the mixing temperature of the LDPE concrete as 200℃, the mixing time of the LDPE concrete is 210 s, and the number of Marshall test piece forming is 50 times on each side,

[0051] According to the Marshall stability and the flying loss index, the medium gradation is selected as the preferred aggregate gradation. The Marshall test piece corresponding to the medium gradation has better high-temperature performance, the flying loss of the medium gradation is smaller, and the anti-flying performance is better.

[0052] Step 4: Based on the selected polyethylene, according to the medium gradation and the initial polyethylene content of 5%, 3%, 6%, 9% and 12% of the mass of polyethylene were selected as the flow modifier content, the preparation process referred to 200℃ as the mixing temperature of LDPE concrete, the mixing time of LDPE concrete was 210s, the forming frequency of Marshall test piece was 50 times on each side, the freeze-thaw splitting test, the flying test and the immersion flying test were carried out on the formed Marshall test piece, the splitting strength, the freeze-thaw splitting strength, the flying loss and the immersion flying loss were used as indexes, the test results could be referred to Table 1, and the flow modifier dosage with the best water stability was selected as 9% of the mass of polyethylene.

[0053] The test method was based on the relevant methods of "Highway Engineering Asphalt and Asphalt Mixture Test Procedures" (JTGE20-2011).

[0054] Table 1

[0055]

[0056] Step 5: When the initial asphalt-aggregate ratio was selected, the medium gradation was selected as the aggregate gradation, 3-5 asphalt-aggregate ratios were selected with 0.5% as the interval, the Marshall test piece was prepared at the corresponding mixing temperature, the air voids and the plastic saturation of the Marshall test piece were calculated, and the air voids-plastic saturation curve and the plastic saturation-plastic saturation curve were drawn with the asphalt-aggregate ratio as the horizontal coordinate and the air voids and the plastic saturation as the vertical coordinate, respectively. The plastic saturation is an index representing the degree of plastic filling between aggregates and reflecting whether the plastic content is appropriate. The air voids reflect the relative content of the void volume of the concrete in the compacted state, which is closely related to the plastic content and performance change of the concrete.

[0057] The minimum asphalt-aggregate ratio OPC min1 and the maximum asphalt-aggregate ratio OPC max1 in the air voids-asphalt-aggregate ratio curve when the air voids range was 18.0%-20.0% were selected, the average value OPC1 of OPC min1 and OPC max1 was calculated,

[0058] The minimum asphalt-aggregate ratio OPC min2 and the maximum asphalt-aggregate ratio OPC max2 in the plastic saturation-plastic saturation curve when the plastic saturation range was 35%-40% were selected, the average value OPC2 of OPC min2 and OPC max2 was calculated,

[0059] The average value OPC of OPC1 and OPC2 was calculated, and OPC was used as the best asphalt-aggregate ratio, and the formula was as follows:

[0060]

[0061]

[0062]

[0063] The optimal cement-aggregate ratio of the LDPE concrete is about 5.7%, and the Marshall test piece prepared according to the optimal cement-aggregate ratio can be used for reference of the test data in Table 2.

[0064] Table 2

[0065]

[0066] The test method is according to the relevant methods in the Test Code for Asphalt and Asphalt Mixture of Highway Engineering (JTGE20-2011).

[0067] Step 6: The polyethylene concrete Marshall test piece is prepared based on the optimal cement-aggregate ratio, the performance index of the polyethylene concrete is screened, the performance of the polyethylene concrete is verified according to the performance index, and the mix proportion of the polyethylene concrete is further optimized according to the technical requirements of the performance index of the polyethylene concrete.

[0068] The performance index of the polyethylene concrete is shown in the following table:

[0069]

[0070] The methods not specified can be obtained according to the conventional methods in the prior art.

[0071] The performance of the PE concrete is verified based on the optimal cement-aggregate ratio of 5.7%, and the results can be referred to Table 3.

[0072] Table 3

[0073]

[0074] It is shown that the performance of the PE concrete with the optimal cement-aggregate ratio meets the technical requirements, and the mix proportion design can be put into use; if the requirements are not met, the materials and gradation should be adjusted, and the mix proportion design should be re-performed.

[0075] The above-described embodiments are only the preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. The equivalent substitutions or transformations made by the person skilled in the art on the basis of the present application are within the protection scope of the present application. The protection scope of the present application is subject to the claims.

Claims

1. A method for mix design of polyvinyl concrete, characterized by The specific steps are ： Step 1: Preliminary selection of polyethylene types based on melting point temperature 70-140℃ and melt index 40-200g / 10min, and selection of aggregate and flow modifier, Step 2: Test the apparent viscosity of polyethylene at different temperatures, draw the apparent viscosity-temperature curve, and select the temperature corresponding to the apparent viscosity equal to 450±30Pa·s as the mixing temperature of polyethylene concrete according to the apparent viscosity range of polyethylene, Step 3: Screen the aggregate gradation range, select a certain number of gradations in the screened aggregate gradation range, select the aggregate, and preliminarily select the polyethylene content to prepare the formed Marshall test piece, and obtain the Marshall stability and flying loss indicators based on the Marshall stability test and standard flying test, and optimize the aggregate gradation according to the results, Step 4: Based on the selected polyethylene, according to the preliminary selection of polyethylene content, and adding different doses of flow modifier, evaluate the improvement effect of the flow modifier from the water stability point of view, respectively carry out freeze-thaw splitting test, flying test and immersion flying test, and select the flow modifier dose with the best water stability, Step 5: Preliminary selection of glue stone ratio, the glue stone ratio is the mass ratio of polyethylene and aggregate, prepare Marshall test piece according to the glue stone ratio, measure the void ratio and polyethylene saturation of the test piece under different glue stone ratio conditions, draw the corresponding curve, and determine the maximum and minimum values of the glue stone ratio according to the void ratio and polyethylene saturation requirement range respectively, and take the average of the maximum and minimum values respectively, and take the average of the two average values to obtain the best glue stone ratio, Step 6: Prepare polyethylene concrete Marshall test piece based on the best glue stone ratio, screen the performance indicators of polyethylene concrete, test the performance of polyethylene concrete according to the performance indicators, and further optimize the mix proportion of polyethylene concrete according to the technical requirements of the performance indicators of polyethylene concrete.

2. The method for mix proportion design of polyvinyl concrete according to claim 1, characterized in that The preliminary selection of polyethylene types based on melting point temperature 70-140℃ and melt index 40-200g / 10min in step 1 is low-density polyethylene.

3. The method according to claim 2, wherein the method is characterized by The temperature corresponding to the apparent viscosity equal to 450±30Pa·s as the mixing temperature of low-density polyethylene concrete is 195-215℃ according to the apparent viscosity range of low-density polyethylene in step 2.

4. The method according to claim 1 or 3, characterized in that The screening aggregate gradation range in step 3 is PC-13 gradation range, which is obtained by removing aggregate with particle size less than 0.075mm according to the standard of SMA-13 asphalt mixture gradation, and three gradations are preliminarily selected in the PC-13 gradation range.

5. The method for designing the mix proportion of polyethylene concrete according to claim 4, characterized in that: The PC-13 gradation range in step 3 is shown in the following table:

6. The method of claim 5, wherein the method further comprises The three gradations preliminarily selected in the PC-13 gradation range in step 3 are coarse gradation, medium gradation and fine gradation, wherein the coarse gradation is the upper limit of PC-13 gradation, the medium gradation is the median value of PC-13 gradation, and the fine gradation is the lower limit of PC-13 gradation, The preliminary selection of polyethylene content is 5.0%-6.0%, and the formed Marshall test piece is prepared with coarse gradation, medium gradation and fine gradation respectively, and the medium gradation is selected as the preferred aggregate gradation according to the Marshall stability and flying loss indicators.

7. The polyethylene concrete mix design method according to claim 6, wherein in step 4, based on the selected polyethylene, 3%, 6%, 9% and 12% of the mass of the polyethylene are selected as the flow modifier content according to the medium gradation and the initial polyethylene content of 5.0%-6.0%, the flow modifier is selected as aliphatic polyester, and Marshall specimens are prepared respectively, and the flow modifier content when the water stability is the best is selected as 9% of the mass of the polyethylene.

8. The method for designing the mix proportion of polyethylene concrete according to claim 7, characterized in that: In step 5, when the initial asphalt-aggregate ratio is selected, the medium gradation is selected as the aggregate gradation, 3-5 asphalt-aggregate ratios are selected with 0.5% as the interval and the initial asphalt-aggregate ratio as the medium value, Marshall specimens are prepared at the corresponding mixing temperatures, the air voids and the plastic saturation of the Marshall specimens are calculated, and the asphalt-aggregate ratio is taken as the horizontal coordinate, the air voids and the plastic saturation are taken as the vertical coordinates respectively, and the air voids-asphalt-aggregate ratio curve and the plastic saturation-asphalt-aggregate ratio curve are drawn. The minimum OPC corresponding to the porosity range of 18.0%-20.0% in the porosity-aggregate ratio curve was selected. min1 And the maximum ratio of OPC to glue stone max1 Request OPC min1 and OPC max1 The average value of OPC1, OPC2 = (OPC1 + OPC3) / 2 The specific steps are OPC2 = (OPC1 + OPC3) / 2 ： , and the average value OPC2 of OPC1 and OPC3 Step 1: Preliminary selection of polyethylene types based on melting point temperature 70-140℃ and melt index 40-200g / 10min, and selection of aggregate and flow modifier, , OPC1 and OPC2 are averaged to obtain the average OPC, and the OPC is taken as the optimal asphalt-aggregate ratio.

9. The method of mix design of polyvinyl concrete according to any one of claims 1 or 5-8, characterized in that In step 6, the performance indicators of the polyethylene concrete are as shown in the following table:

Images