RU2745437C1 - Polymeric soil stabilizer used for strengthening and stabilizing soils in industrial and civil construction, and polymer-cement-soil mixture - Google Patents

Abstract

FIELD: road construction.SUBSTANCE: inventions relates namely to strengthening the bearing layer of soil during the construction of the foundations of roads, buildings, sidewalk paths, suitable for use on sandy, sandy loam and clay soils in combination with other materials, such as asphalt granulate, and also without it. Polymeric soil stabilizer consists of polymeric macromolecules dissolved in water - polyacrylamide, copolymer of acrylamide and sodium acrylate, copolymer of acrylamide and sodium methacrylate with the addition of oxyethylated sorbitan - polysorbate-80, polysorbate-60, polysorbate-20 as an emulsifier, a hydrophosphate, while polymer macromolecules have an average molecular weight of 8 to 20 MDa, with the following ratio of components, wt%: polymer macromolecules 0.25-3.0, oxyethylated sorbitan 0.1-1.0, tartrazine 0.005, water for the rest. The polymer-cement-soil mixture contains, wt%: soil 85–93.9, Portland cement 6.0–7.0, an aqueous solution of the above polymer soil stabilizer, previously diluted with water to the required concentration, 0.1–8.0.EFFECT: increased hydrophobization and strength characteristics of hardened soil.3 cl, 4 tbl

Description

The invention relates to the field of creating a water-soluble polymer composition applicable to strengthen the load-bearing soil layer during the construction of the foundations of roads, buildings, sidewalk paths. The invention is suitable for use on sandy, sandy loam and clay soils of natural origin in combination with other materials, for example, asphalt granulate or Portland cement, as well as without them.

In world practice, various methods of strengthening soils are known using both mineral binders and various organic additives, namely: oil refining products, various surfactants, water-borne polymer binders. So, for example, for unpopulated soils used in the construction of roads, airfields and similar structures, it is proposed to use highly resinous oil with the addition of a cationic product based on tertiary amines and chloromethylated phenolic oils (ed. USSR certificate No. 360356, 28.11.1972).

When strengthening clay soils to increase strength, water resistance and frost resistance, it is proposed to add polymerized fatty amine, lime, coal tar (ed. USSR certificate No. 487204, 05.10.1975) to clay soil, or, along with this, use a mixture of copper sulfate with aniline in the form of separate components or more effectively in the form of a copper-aniline complex compound (ed. certificate of the USSR No. 834306, 05/30/1981). However, the listed methods of soil strengthening involve the use of rather toxic amino and phenolic derivatives of organic compounds, as well as a copper-aniline complex, while in the corresponding descriptions of the inventions there is no actual data confirming the achieved level of soil hardening due to the recommended additives.

Known road mixture, consisting of soil and plasticizing additives, which is proposed to use divinylstyrene latex, its amount in relation to 100 wt.h. the soil is 2-4 parts by weight. (ed. certificate of the USSR No. 481661, 25.08.1975). The disadvantage of this invention is a rather large volume to achieve the required performance of expensive divinylstyrene latex when strengthening the soil. In addition, the description and the claims do not indicate any requirements for the composition of the copolymer in latex, the charge and size of its latex particles, colloidal-chemical characteristics that radically affect the compatibility of latex with the soil, the nature of the soil and the final results achieved from strengthening.

Known mixture for soil concrete, related to building materials, namely to soil concretes used to stabilize clay soils in road bases (US Pat. No. 2392244, "Mix for soil concrete", from 20.06.2010), contains, wt%: clay soil - 78-83, Portland cement - 4-8, chemical additive - enzyme preparation "Dorzin" - 0.03-0.06, water - the rest.

The closest in technical essence to the claimed invention is a road polymer-cement-soil mixture (US Pat. No. 2373321 dated 20.11.2009), relating mainly to the construction of highways, contains, wt% (dry): soil 90, cement 9.35- 9.4, latex SKS-65GP 0.5, mechanically activated cellulose 0.1-0.15.

The disadvantage of this mixture, as well as of all the above mixtures, is the insufficient bearing capacity of the soil base, a longer set of the M100 strength class required according to GOST 23558-94, as well as a high consumption of inorganic binder - cement.

The purpose of the development of the present invention is to create a composition of a polymer stabilizer of the bearing layer of the soil, used in conjunction with Portland cement in order to modify the operational properties of the soil, namely to increase the strength characteristics, as well as to increase the hydrophobization.

The specified goal and technical result are implemented as follows. The proposed polymer soil stabilizer consists of polymeric macromolecules dissolved in water - polyacrylamide, a copolymer of acrylamide and sodium acrylate, a copolymer of acrylamide and sodium methacrylate with the addition of oxyethylated sorbitan - polysorbate-80, polysorbate-60, polysorbate-20 as an emulsifier to impart pleasant organoleptic properties to the soil stabilizer, while polymer macromolecules have an average molecular weight of 8 to 20 MDa, with the following ratio of components, wt%: polymer macromolecules 0.25 - 3.0, ethoxylated sorbitan 0.1 - 1.0 , tartrazine 0.005, water - the rest. The number of sodium acrylate units does not exceed 30% of the total number of monomer units in the composition of the copolymer polymolecule, the number of sodium methacrylate units does not exceed 25% of the total number of monomer units in the composition of the copolymer polymolecule. The proposed polymer-cement-soil mixture using the above polymer soil stabilizer contains components at the following ratio, wt%: soil 85 - 93.9, Portland cement 6.0 - 7.0, an aqueous solution of polymer soil stabilizer, previously diluted with water to the required concentration, 0 , 1 - 8.0.

Table 1. Physical characteristics of the polymer soil stabilizer.

Physical characteristics of polymer soil stabilizer: appearance colored liquid smell practically absent mass fraction of basic substances,% 0.45-0.95 pH at normal 6.7-7.3 relative density, g / cm ³ 1 ± 0.02 particle size, μm 0.05-1.0 boiling point, ^о С 99.5 solubility miscible with water viscosity at normal mPa s 2.0 ± 0.3

With the introduction of a polymer stabilizer into clay soil in a ratio obtained by selecting the composition of mixtures together with an inorganic binder (Portland cement), reacting with chemically bound water in clay-forming minerals, the polymer modifier forms chemically resistant and strong compounds that give the soil a more ordered structure, with the formation of a primary structural framework, overgrown with calcium hydrosilicates, and, ultimately, creating a material of very high strength and low water absorption capacity.

To study the effect of a polymer stabilizer on the properties of clay soils, a detailed analysis of the mechanical properties of clay soils reinforced with Portland cement and polymer soil stabilizer was carried out under laboratory conditions. In laboratory conditions, cylindrical samples (GOST 12801-98) were formed, containing in their composition a different number of components that make up the stabilizer with a constant amount of binder - Portland cement. After the selection of the optimal composition, work was carried out to select the optimal amount of binder (tables 2 and 3).

Table 2. Composition of samples of an aqueous solution of a polymer soil stabilizer, previously diluted with water and used for further tests:

Sample No. Aqueous solution of polymer soil stabilizer, 50 g. Polymer molecules, wt% Emulsifier,
wt% Dye,
wt% Water,
wt% one 0.5 0.25 0.005 the rest is up to 100% 2 1.0 0.25 3 0.75 0.25 four 0.25 0.1 five 0.5 0.5 6 1.0 0.5 7 0.75 0.5 8 0.25 0.25 nine 0.5 0.0 ten 1.0 0.0 eleven 0.5 0.25 12 3.0 1.0 thirteen 0.5 0.25 14 0.5 0.25

Table 3. Examples of experimental laboratory work on the selection of the composition of the polymer-cement-soil mixture using a soil stabilizer.

Sample No. Soil stabilizer according to table 2 Portland cement, g (wt%) Priming Soil stabilizer aqueous solution, g (wt%) Clay, g (wt%) Slag,
g (wt%) one 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) 2 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) 3 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) four 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) five 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) 6 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) 7 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) 8 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) nine 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) ten 50 (5.025) 65 (6,533) 800 (80.402) 80 (8.04) eleven 50 (5.0) 70 (7.0) 800 (80.0) 80 (8.0) 12 50 (4.98) 75 (7.46) 800 (79.6) 80 (7.96) thirteen 50 (5.06) 60 (6.06) 800 (80.8) 80 (8.08) 14 50 (5.102) 50 (5.102) 800 (81,633) 80 (8,163)

Tests for the physical and mechanical properties of the polymer-modified mixture of hardened soil were carried out in accordance with GOST 30491-2012 (table 4).

Table 4. Physical and mechanical tests of polymer-cement-soil mixtures, reinforced with a soil stabilizer after 14 days.

Sample No. Compressive strength, MPa, at 20 ° C, MPa Compressive strength of water-saturated samples at a temperature of 20 ° C, MPa Ultimate tensile strength in bending of water-saturated samples at a temperature of 20 ° C, MPa Frost resistance coefficient Swelling,% by volume Strength grade one 17.5 6.0 1,3 more than 0.85 less than 2.0 M100 2 15.4 5.8 1,2 3 15.8 6.6 1,2 four 15.7 6.8 1,3 five 12.8 3.8 0.9 6 11.2 2.8 0.8 7 11.0 2.8 0.9 8 11.7 2.5 0.8 nine 17.3 1.8 0.6 ten 16.6 2.1 0.6 eleven 17.4 6.2 1,3 12 17.6 6.3 1.4 thirteen 17.1 5.6 1,3 14 16.5 5.4 1,2

Based on the tests carried out, the optimal composition of the polymer-cement-soil mixture was selected, containing 88.5% of soil, 6.5% of cement and 5.0% of an aqueous solution of a polymer stabilizer, previously diluted with water to the required concentration. All tested samples at fourteen days of age correspond to a strength class of at least M100 (GOST 23558-94), however, it was found that the addition of an emulsifier to the composition of the stabilizer improves the hydrophobization of the hardened soil (comparison of samples 1 and 9), while the optimal mass ratio of polymer to emulsifier is 2 : 1, with an increase in the amount of the second, there is a deterioration in the physical and mechanical properties of the hardened soil (comparison of samples 1 and 5). An increase in the amount of binder does not lead to any significant improvement in the physicochemical properties of the hardened soil, therefore, the optimal content is 6.0-7.0% of Portland cement from the total mass of the polymer-cement-soil mixture.

Scaling the above-described development to construction sites will make it possible to obtain solid foundations with increased and uniform stability of the roadway during operation.

Claims (3)

1. Polymeric soil stabilizer, characterized by the fact that it consists of polymeric macromolecules dissolved in water - polyacrylamide, a copolymer of acrylamide and sodium acrylate, a copolymer of acrylamide and sodium methacrylate with the addition of oxyethylated sorbitan - polysorbate-80, polysorbate-60, as a polysorbate-20 and a water repellant, a synthetic azo dye - tartrazine, while polymer macromolecules have an average molecular weight of 8 to 20 MDa, with the following ratio of components, wt%: polymer macromolecules 0.25-3.0, oxyethylated sorbitan 0.1-1.0 , tartrazine 0.005, water - the rest. 2. Polymeric soil stabilizer according to claim 1, characterized in that the number of sodium acrylate units does not exceed 30% of the total number of monomer units in the copolymer polymolecule, the number of sodium methacrylate units does not exceed 25% of the total number of monomer units in the copolymer polymolecule. 3. Polymer-cement-soil mixture using a polymer soil stabilizer according to claim 1 or 2, containing components at the following ratio, wt.%: Soil 85-93.9, Portland cement 6.0-7.0, aqueous solution of polymer soil stabilizer, previously diluted water to the required concentration, 0.1–8.0.