Study On The Impermeability Of PAM-Silicone Cement Soil

With the development of social production, Soil cement is widely used in municipal roads, water and seepage slope protection and other projects, which is huge quantities. The cement soil is used in these projects, The one hand, because the cement-soil belongs to semi-rigid material, which itself has the advantage of high strength of the rigid barrier material(such as impermeable concrete), but also has the advantage of large deformation can occur of the flexible impermeable material(such as a polymer impermeable material). On the other hand, it is low-cost and convenient for the construction. It not only can greatly save resources, but also be considerable for social benefits and economic to use cement-soil, so it is necessary to study the anti-permeability of cement soil.Of course, we use these seepage control works of lower cost cement soil to replace the original expensive rigid or flexible waterproof material, the primary indicator is the study of how the impermeability of cement soil samples, can meet the requirements of the project, if reached can not claim to have any way to make soil cement barrier properties to meet the requirements, so improving the barrier properties of soil cement is an urgent issue.Currently, the research on soil cement barrier impermeability is adopting the theory of impermeability of imitating of cement mortar or concrete, which is done by adding some simple chemical admixtures barrier properties such as sulfur calcium alumina or some substance tiny pores between the particles of soil cement filling way to improve the soil cement. It can be improved for the anti-permeability of cement soil by adding high polymer and coupling agent to the cement soil at the same time from two aspects of physical and chemical properties. Frequently-used polyacrylamide polymer having a good flocculation and water retention can fill tiny pores between the particles of soil cement, and adjust the moisture content of the soil inside the cement, and ensure that the internal structure of soil cement does not easily damage for the changing of the external humidity conditions; Chemical reaction between the coupling silicone and cement base, which can form a network cross linked structure and a hydrophobic membrane of interior of soil cement, can effectively prevent outside water from entering the interior material, thereby enhancing the barrier properties of cement soil.It is by testing the soil cement mixed with a certain amount of polyacrylamide and silicone to improve its barrier properties. Using cement content of 13% and water-cement ratio of 1.5 to study its anti-permeability systematic and in-depth. Using the experimental data and Excel and Matlab gets the conclusion that recombination between polyacrylamide and silicone is better, and how much recombination is better. It can analyze its internal structural changes by the scanning electron microscopy(SEM) tests of the Admixtures for optimal type and optimal dosage of cement soil.Finally, as the marker, the permeability coefficient of the optimal dosage of admixture optimum combination of 28 d age of soil water obtained prediction data by the gray model. By comparing with the measured values, it can verify the accuracy requirements are met or not. The main contents and results are as follows:(1) There is the permeability coefficient by the test under the condition of adding different dosage polyacrylamide(0%, 1%, 3% and 5%),different contents silicone(0%?1%?3%and5%), and at the same time two kinds of mixed cement admixture soil at different ages(3d, 7d, 14 d, 28d). Cement soil incorporation of an appropriate amount of silicone and polyacrylamide can effectively improve the barrier properties of soil cement by the range analysis and analysis of variance of the cement soil permeability. And it add two cement admixture soil impermeability performance is better than just adding one soil cement admixture. When the age of 3d, 7d, 14 d, the influence of barrier properties on polyacrylamide is greater than on silicone. When the age of 28 d, the influence of barrier properties on silicone is greater than on polyacrylamide;(2) Combined with MATLAB, Excel and other software analysis of experimental results, and three cases experimental by adding polyacrylamide, or adding silicone, or adding both polyacrylamide and silicone to be analysis of regression, and taking fixed polyacrylamide content, the analysis of influence of different organic silicon content of the cement-soil impermeability, we can get the conclusion: when polyacrylamide content of 0%, the corresponding optimal organic silicon content of 1%, when polyacrylamide dosage is 1%, corresponding to the most preferably silicone content of 5%, when the polyacrylamide content of 3%, the corresponding optimal organic silicon content of 3%, when the polyacrylamide content of 5%, the corresponding optimal organic silicon doped an amount of 5%;(3) Compare selected four group of optimal dosage, and taking into account the economy, it can be conclusion that the best soil cement admixture content is the two condition: 1%polyacrylamide dosage, 5% silicone content and 3%polypropylene, 3% silicone content. There is a experiment of the scanning electron microscope for the two best combination of 3d, 7d, 14 d, 28 h,and analyzing its internal structural changes;(4) By Grey System GM(1,3) model of the above two best specimens 28 d test raw data simulation, the error ranging of simulation results and measured values is in the range of engineering applications, and using the model predict the remaining part of the data and comparing with the measured value, the error is within the allowable range, which provide a way of forecasting the impermeability;In summary, under the condition of the incorporation of polyacrylamide and silicone, cement soil can effectively improve the barrier properties, and the age and two kinds of admixture content can affect the barrier properties of soil cement. Through test, considering the economic and rationality, it is determined that the optimal dosage groups. And the theory of gray system GM(1,3) model of optimal dosage of the two groups of test raw data 28 d simulate the error in within the allowable range, it can be used as practical engineering prediction model.