Anti-shrinkage foam light soil prepared from Yellow River sand and preparation method of anti-shrinkage foam light soil

Abstract

The invention provides anti-shrinkage foam light soil prepared from Yellow River sand and a preparation method of the anti-shrinkage foam light soil. The anti-shrinkage foam light soil comprises the following components in percentage by weight: 38-50% of cement, 12-31% of Yellow River sand, 26-34% of water and 4-9% of foam. The flood discharge accumulated Yellow River sand is added into the foam light soil to serve as fine aggregate to be applied to roadbed engineering, a Yellow River sand-based foam light soil mix proportion formula and a corresponding foam light soil mix proportion formula of target strength preparation are provided, and the Yellow River sand is used for replacing part of cement in the foam light soil, so that the use amount of cement and water can be reduced; the drying shrinkage of the foam light soil is reduced, the damage of sediment deposition to the riverway is relieved by utilizing the Yellow River sand, and the economic benefit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering materials, and in particular is a shrinkage-resistant foam lightweight soil prepared by using Yellow River sand and a preparation method thereof. Background Art

[0002] The Yellow River is the river with the highest sediment content in the world, with an average annual sediment transport of about 1.6 billion tons, which has led to the continuous rise of the riverbed. The riverbed rise and flood risks in the lower reaches of the Yellow River have posed a huge threat to the local social economy. Scientific treatment of Yellow River sand and its resource utilization are of great significance to alleviating the accumulation of sediment in the Yellow River. There are already some methods for resource utilization of Yellow River sand, such as using Yellow River sand to make defense stones, hollow bricks, and concrete.

[0003] With the economic development and the increasing traffic volume, a large number of highways in my country need to be widened. Foam lightweight soil has good self-stabilization, light weight, good durability and strong anti-freezing ability, and can be widely used in slope roadbed widening and soft foundation treatment.

[0004] The current foam lightweight soil has the following problems:

[0005] 1. Large shrinkage, easy to cause cracking;

[0006] 2. The water-cement ratio is large. If other anti-shrinkage materials are added, the cost will be high;

[0007] 3. The amount of cement used is large, and the pH value of lightweight soil is high, which is not friendly to the environment;

[0008] 4. The required mix ratio of added materials to achieve the design strength is unclear and cannot be designed and promoted.

[0009] The main materials contained in foamed lightweight soil are cement, water, foam, and admixtures. The water-cement ratio is very high, and the maximum can reach more than 0.6, so a large amount of water needs to be added to the foamed lightweight soil. Foamed lightweight soil has a large shrinkage, which can be about 7 times greater than that of ordinary cement concrete. Only fine aggregates can be added to foamed concrete, but too much inert aggregate will lead to a decrease in the strength of the concrete. There is currently no systematic and in-depth research summary on the crack control technology of large-volume foamed lightweight soil in China. When cracks appear in foamed lightweight soil, the integrity, stability, and durability of its structure will be affected. Severe cracks may cause large-scale settlement, collapse, or destruction of the overall structure, resulting in major quality and safety accidents. Summary of the invention

[0010] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a shrinkage-resistant foam lightweight soil prepared using Yellow River sand and a preparation method thereof, which solves the problem that when cracks appear in the foam lightweight soil, the integrity, stability and durability of its structure will be affected. When the cracks are serious, large-scale settlement, collapse or destruction of the overall structure may occur, causing major quality and safety accidents.

[0011] The technical solution of this application is:

[0012] The invention discloses a shrinkage-resistant foamed lightweight soil prepared by using Yellow River sand, which comprises the following components in weight percentage: 38-50% cement, 12-31% Yellow River sand, 26-34% water and 4-9% foam.

[0013] A method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand comprises the following steps:

[0014] S1: According to the design wet weight R k , compressive strength F, material properties to determine cement density

[0015] ρc, Yellow River sand density ρs, foam density ρf, richness coefficient K, and the mass R of cement in each cubic meter of foam lightweight soil is obtained through the mix ratio formula c , the quality of Yellow River sand s , water quality R w , Foam quality R f ;

[0016] S2: The mixing station adds water to cement and Yellow River sand in corresponding proportions and stirs them into a uniform slurry, sucks the diluted foaming liquid into the foaming machine for foaming, and uses a mixer to fully stir the foamed lightweight soil slurry and the foam for 4-8 minutes to obtain the foamed lightweight soil.

[0017] Furthermore, in step S2, the dilution ratio of the foaming liquid is 1:30-1:60.

[0018] Furthermore, the mix ratio formula of the foam lightweight soil is:

[0019] F=-1.166+0.0083*R c +0.0012*R s

[0020]

[0021] R w =94.886+0.304*R c +0.079R s

[0022]

[0023] Where: F is the compressive strength of foam lightweight soil (MPa);

[0024] a is the mixing ratio of Yellow River sand;

[0025] R c is the mass of cement in each cubic meter of foam lightweight soil;

[0026] R s is the mass of Yellow River sand in each cubic meter of foamed light soil;

[0027] R w is the mass of water in each cubic meter of foam lightweight soil;

[0028] R f is the mass of foam in each cubic meter of foam lightweight soil;

[0029] R k is the design wet weight;

[0030] ρc is cement density;

[0031] ρs is the density of Yellow River sand;

[0032] ρf is the foam density;

[0033] K is the richness coefficient.

[0034] Furthermore, the richness coefficient K is 1.1-1.3.

[0035] Furthermore, the designed wet weight of the foamed lightweight soil is 500 kg / m 3 -750kg / m 3 .

[0036] Furthermore, the cement is P.O42.5 cement.

[0037] Furthermore, the moisture content of the Yellow River sand is less than 5%, the residue on a 0.08 mm square sieve is 45%-55%, and the residue on a 0.15 mm square sieve is 85%-95%.

[0038] Furthermore, the Yellow River sand is the accumulated mud and sand after the Yellow River discharges flood water during the flood season, and the density of the Yellow River sand is 2200kg / m 3 .

[0039] Furthermore, the median particle size of the Yellow River sand is 86.44 μm, the mass fraction of silt in the Yellow River sand is 44.39%, and the mass fraction of clay in the Yellow River sand is 0%.

[0040] The specific beneficial effects of the present invention include:

[0041] 1. The present invention adds the Yellow River sand accumulated during flood discharge into the foamed lightweight soil as fine aggregate for roadbed engineering, proposes a mix ratio formula of the Yellow River sand-based foamed lightweight soil and a mix ratio formula of the foamed lightweight soil corresponding to the target strength, and uses the Yellow River sand to replace part of the cement in the foamed lightweight soil to reduce the amount of cement and water, reduce the drying shrinkage of the foamed lightweight soil, and use the Yellow River sand to alleviate the harm of siltation to the river channel, and improve economic benefits;

[0042] 2. The present invention has low cost. The use of Yellow River sand instead of cement saves cement cost and reduces the amount of cement and water. Meanwhile, the particle size of Yellow River sand is small (20-350 μm), which has relatively little effect on foam, and the particle size distribution is relatively concentrated. The impurity content is very low and does not require excessive treatment.

[0043] 3. The foamed lightweight soil in the present invention shrinks when it dries. The more Yellow River sand is added, the smaller the shrinkage of the foamed lightweight soil is.

[0044] 4. The present invention proposes a formula for the mix ratio of the Yellow River sand-based foamed lightweight soil and a formula for the mix ratio of the foamed lightweight soil corresponding to the target strength, and the ratio of each material can be designed according to the target strength;

[0045] 5. The present invention uses flood discharge to accumulate Yellow River sand, which is a waste utilization, reduces carbon dioxide emissions from buildings, and alleviates sediment accumulation in the Yellow River. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0047] Figure 1 This is the distribution map of the grain size of the Yellow River sand;

[0048] Figure 2 It is a comparison chart of the compressive test value of foam lightweight soil under different working conditions and the predicted value of compressive strength regression model;

[0049] Figure 3 This is the relationship curve between the optimal amount of Yellow River sand and the predicted compressive strength;

[0050] Figure 4 Design wet weight 600kg / m 3 The relationship between the amount of Yellow River sand added and the shrinkage rate;

[0051] Figure 5 This is the flow chart for the preparation of Yellow River sand foam lightweight soil. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the core concept of the present invention and the following embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] The present application provides these embodiments to make the present application thorough and complete, and to fully express the scope of the present application to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.

[0054] A shrinkage-resistant foamed lightweight soil prepared using Yellow River sand includes the following components in weight percentage: 38-50% cement, 12-31% Yellow River sand, 26-34% water, and 4-9% foam. The mass proportion is the unit volume usage of each substance / total unit volume mass, and the mass fraction is the unit volume usage of each substance. Therefore, the mass fractions of each raw material are: 196-395 parts of cement, 58-232 parts of Yellow River sand, 162-223 parts of water, and 33-47 parts of foam.

[0055] A method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand comprises the following steps:

[0056] S1: According to the design wet weight R k , compressive strength F, material properties to determine cement density ρc, Yellow River sand density ρs, foam density ρf, richness coefficient K, and the mass R of cement per cubic meter of foam lightweight soil is obtained through the mix ratio formula c , the quality of Yellow River sand s , water quality R w , Foam quality R f ;

[0057] S2: The mixing station adds water to cement and Yellow River sand in corresponding proportions and stirs them into a uniform slurry, sucks the diluted foaming liquid into the foaming machine for foaming, and uses a mixer to fully stir the foamed lightweight soil slurry and the foam for 4-8 minutes to obtain the foamed lightweight soil.

[0058] Specifically, the flow values ​​of the various material components of the initially configured foam lightweight soil are tested as shown in Table 1:

[0059] Table 1: Foam lightweight soil flow values ​​at different water-cement ratios

[0060]

[0061]

[0062]

[0063]

[0064] The material consumption with the flow value closest to 180 mm under different working conditions in Table 1 was selected to establish a regression model. The water consumption was set as a variable, and the cement consumption and Yellow River sand consumption were set as independent variables. The regression model was: R w =94.886+0.304*R c +0.079*R s , R 2 =0.97.

[0065] In the formula, R w is the mass of water in each cubic meter of foam lightweight soil;

[0066] R c is the mass of cement in each cubic meter of foam lightweight soil;

[0067] R s is the mass of Yellow River sand in each cubic meter of foamed light soil;

[0068] R 2 It is an indicator of the goodness of fit of the regression model, which indicates the percentage of variation in the dependent variable that the independent variable can explain. 2 The closer it is to 1, the better the model fit is and the closer the predicted value is to the true value.

[0069] Table 1 establishes a regression model of water consumption, cement and Yellow River sand consumption according to the content of each component closest to the flow value of 180 mm, that is, the flow value marked with an underline, to determine the amount of each substance. The 28-day compressive strength of foamed lightweight soil with different wet density and Yellow River sand content is tested and a regression model is established to obtain the relationship between the strength of foamed lightweight soil and the amount of cement and Yellow River sand.

[0070] Specifically, the mix ratio formula of the foam lightweight soil is:

[0071] F=-1.166+0.0083*R c +0.0012*R s

[0072]

[0073] R w =94.886+0.304*R c +0.079R s

[0074]

[0075] Where: F is the compressive strength of foam lightweight soil (MPa);

[0076] a is the mixing ratio of Yellow River sand;

[0077] R c is the mass of cement in each cubic meter of foam lightweight soil;

[0078] R s is the mass of Yellow River sand in each cubic meter of foamed light soil;

[0079] R w is the mass of water in each cubic meter of foam lightweight soil;

[0080] R f is the mass of foam in each cubic meter of foam lightweight soil;

[0081] R k is the design wet weight;

[0082] ρc is cement density;

[0083] ρs is the density of Yellow River sand;

[0084] ρf is the foam density;

[0085] K is the richness coefficient, which depends on the quality of the foaming agent, the foaming time and the loss when the foam is added to the slurry and then mixed. For foaming agents with good stability, the richness coefficient is 1.1 to 1.3.

[0086] Yellow River sand is the sediment accumulated after the Yellow River discharges flood water during the flood season, with a density of 2200kg / m 3 , the median particle size is 86.44μm, the mass fraction of clay (diameter less than 5μm) is 0%, the mass fraction of silt (diameter 5-75μm) is 44.39%, and the mud content (particles with a diameter greater than 0.020 mm are called sand) is 43.34%. Particle distribution is as follows Figure 1 shown.

[0087] Specifically, Figure 1 The test Yellow River sand was taken from the surface sediments on the side of the river channel under the Yellow River flood discharge in Kaifeng. The laboratory used a laser particle size analyzer to measure the particle size of the test Yellow River sand, which was mainly distributed between 20-350μm, with the highest content of sand particles with a particle size of 86.4μm, accounting for 9.1%. The mass fraction of clay was 0%, the mass fraction of silt was 44.39%, the mud content was 0.13%, and the specific surface area was 73.7m2 / kg.

[0088] Specifically, Figure 2 The compressive strength test values ​​and compressive strength regression model prediction values ​​of foam lightweight soil under different working conditions. The designed wet weight in the figure is 500kg / m 3 , 550kg / m3 , 600kg / m 3 , 650kg / m 3 , 700kg / m 3 , 750kg / m 3 The 28-day compressive strength values ​​of foam lightweight soil under the conditions of Yellow River sand mixing ratio of 0%, 10%, 20%, 30%, 40%, and 50%. As the wet density of foam lightweight soil increases, the compressive strength increases accordingly; the more Yellow River sand is added, the smaller the compressive strength.

[0089] According to the compressive strength test values ​​of foam lightweight soil specimens at 28 days under different working conditions, a strength prediction regression model was established. The independent variables were cement consumption, Yellow River sand consumption, water consumption and foam consumption per square meter of foam lightweight soil, and the variable was the 28-day compressive strength. In the regression process, the variables water consumption and foam consumption were discarded, and cement consumption and Yellow River sand consumption were retained.

[0090] The regression model is: compressive strength F = -1.166 + 0.0083 * R c +0.0012*R s , R 2 =0.971.

[0091] F is the compressive strength of foam lightweight soil (MPa);

[0092] R c is the mass of cement in each cubic meter of foam lightweight soil;

[0093] R s is the mass of Yellow River sand in each cubic meter of foamed light soil;

[0094] R 2 It is an indicator of the goodness of fit of the regression model, which indicates the percentage of variation in the dependent variable that the independent variable can explain. 2 The closer it is to 1, the better the model fit is and the closer the predicted value is to the true value.

[0095] According to the regression model, the compressive strength of foamed lightweight soil is mainly related to the amount of cement and the amount of Yellow River sand, and the amount of cement has the greatest impact on the compressive strength of foamed lightweight soil.

[0096] Figure 3 This is a curve comparison of the relationship between the optimal amount of Yellow River sand and the predicted compressive strength, combined with the engineering example:

[0097] Wet weight is 500kg / m 3 When the safety strength is 0.6MPa, the maximum amount of Yellow River sand is 34%.

[0098] Wet weight is 550kg / m 3When the safety strength is 0.8MPa, the maximum amount of Yellow River sand is 36%.

[0099] Wet weight is 600kg / m 3 When the safety strength is 1.0MPa, the maximum amount of Yellow River sand is 37%.

[0100] Wet weight is 650kg / m 3 When the safety strength is 1.2MPa, the maximum amount of Yellow River sand is 40%;

[0101] Wet weight is 700kg / m 3 When the safety strength is 1.4MPa, the maximum amount of Yellow River sand is 40%;

[0102] Wet weight is 750kg / m 3 When the safety strength is 1.5MPa, the maximum content of Yellow River sand is 45%. Therefore, the optimal content of foamed light soil Yellow River sand used in roadbed is 35%.

[0103] Figure 4 Design wet weight 600kg / m 3 The shrinkage rate of different proportions of Yellow River sand replacing cement, the wet weight of foam lightweight soil is 600kg / m 3 The shrinkage of foam lightweight soil decreases with the increase of the amount of Yellow River sand added. When the amount of Yellow River sand added is 50%, the shrinkage rate is 653*106, which is 18.3% lower than the shrinkage when the amount of Yellow River sand added is 0%.

[0104] Case Study:

[0105] A highway embankment in Xinxiang has a fill height of 13m. The 8m above the bottom layer is filled with raw soil and gravel, and the upper layer is a 5m foam lightweight soil fill embankment with a designed wet density of 550kg / m 3 , 28-day compressive strength ≥ 0.8MPa, roadbed 0.8m, designed wet weight 600kg / m 3 , 28-day compressive strength ≥1.0MPa.

[0106] According to the target strength, the foam lightweight soil mix ratio formula is obtained:

[0107]

[0108] The cement is 42.5 ordinary Portland cement, and the Yellow River sand is the accumulated silt after the Yellow River flood season, with a moisture content of less than 5% and a density of 2200g / cm 3, particle size distribution 20-350um, median particle size 76um, foam is foamed by anionic surfactant, physical foaming method is adopted, its density is 49kg / m3, water seepage rate is 25-31%, and settlement distance is 6-7mm. The preparation method of Yellow River sand foam lightweight soil is as follows: cement, Yellow River sand, water, and foam are weighed according to the designed wet density component ratio.

[0109] At the mixing station, cement and Yellow River sand in corresponding proportions are added with water and stirred into a uniform slurry. The cement foaming agent diluted 40 times is sucked into a high-pressure air foaming machine for foaming. The mud and foam are added to a JZC concrete mixer and stirred for 4-8 minutes at a mixer speed of 15r / min to obtain the foamed lightweight soil.

[0110] The measured wet weight of foam lightweight soil used for embankment filling is 560kg / m 3 The 28-day compressive strength is 0.83MPa, and each cubic meter of foam lightweight soil saves 100kg of cement; the wet weight of foam lightweight soil used for roadbed filling is 613kg / m 3 , 28-day compressive strength is 1.08MPa, and each cubic meter of foam lightweight soil saves 120kg of cement.

[0111] The present invention adds the Yellow River sand accumulated during flood discharge into the foamed lightweight soil as fine aggregate for roadbed engineering, and proposes a formula for the mix ratio of the Yellow River sand-based foamed lightweight soil and a formula for preparing the foamed lightweight soil mix ratio corresponding to the target strength. The foamed lightweight soil using the Yellow River sand to replace part of the cement can reduce the amount of cement and water, reduce the drying shrinkage of the foamed lightweight soil, use the Yellow River sand to alleviate the harm of siltation to the river channel, and improve economic benefits.

[0112] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0113] The above content shows and describes the basic principles, main features and beneficial effects of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A shrinkage-resistant foamed lightweight soil prepared using Yellow River sand, characterized in that: The invention comprises the following components in weight percentage: 38-50% cement, 12-31% Yellow River sand, 26-34% water and 4-9% foam.

2. A method for preparing shrinkage-resistant foamed lightweight soil prepared by using Yellow River sand, comprising the shrinkage-resistant foamed lightweight soil prepared by using Yellow River sand as claimed in claim 1, characterized in that: The following steps are involved: S1: According to the design wet weight R k , compressive strength F, material properties to determine cement density 𝝆c, Yellow River sand density 𝝆s, foam density 𝝆f, richness coefficient K, and the mass R of cement per cubic meter of foam lightweight soil is obtained through the mix ratio formula c , the quality of Yellow River sand s , water quality R w , Foam quality R f ; S2: The mixing station adds water to cement and Yellow River sand in corresponding proportions and stirs them into a uniform slurry, sucks the diluted foaming liquid into the foaming machine for foaming, and uses a mixer to fully stir the foamed lightweight soil slurry and the foam for 4-8 minutes to obtain the foamed lightweight soil.

3. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to claim 2, characterized in that: In step S2, the dilution ratio of the foaming liquid is 1:30-1:

60.

4. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to claim 2, characterized in that: The mix ratio formula of the foam lightweight soil is: Where: F is the compressive strength of foam lightweight soil (MPa); a is the mixing ratio of Yellow River sand; R c is the mass of cement in each cubic meter of foam lightweight soil; R s is the mass of Yellow River sand in each cubic meter of foamed light soil; R w is the mass of water in each cubic meter of foam lightweight soil; R f is the mass of foam in each cubic meter of foam lightweight soil; R k is the design wet weight; 𝝆c is the density of cement; 𝝆s is the density of Yellow River sand; 𝝆f is the foam density; K is the richness coefficient.

5. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to any one of claims 2 to 4, characterized in that: The richness coefficient K is 1.1-1.

3.

6. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to any one of claims 2 to 4, characterized in that: The designed wet weight R of the foam lightweight soil k 500 kg / m 3 -750 kg / m 3 .

7. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to any one of claims 2 to 4, characterized in that: The cement used is P.O42.5 cement.

8. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to any one of claims 2 to 4, characterized in that: The moisture content of the Yellow River sand is less than 5%, the residue on a 0.08 mm square sieve is 45%-55%, and the residue on a 0.15 mm square sieve is 85%-95%.

9. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to any one of claims 2 to 4, characterized in that: The Yellow River sand is the accumulated mud and sand after the Yellow River discharges flood water during the flood season. The density of the Yellow River sand is 2200kg / m 3 .

10. The method for preparing shrinkage-resistant foamed lightweight soil using Yellow River sand according to any one of claims 2 to 4, characterized in that: The median particle size of the Yellow River sand is 86.44 μm, the mass fraction of silt in the Yellow River sand is 44.39%, and the mass fraction of clay in the Yellow River sand is 0%.

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