Composition Design And Mechanism Investigation Of Corrosion Resistance Cement

Portland cement is one of the most commonly used building materials. However, the composition and the internal pore structure of cement lead to poor corrosion resistance. The lack of durability of concrete structures, results in premature failure and landslide damage accidents have occurred and caused a huge loss.We have studied the influence on the mechanical properties of cement, sulfate resistance and porosity of the impact of such changes by adding calcium acrylate and acrylamide in this paper. Using scanning electron microscope (SEM), X-ray diffraction (XRD), mercury porosimeter to characterize the changes in microstructure of cement and porosity change in cement stone added with calcium acrylate and acrylamide, and mechanisms were analyzed.The results showed: base on standard of water requirement for normal consistency of cement paste and setting time, adding acrylamide significantly reduced the water usage, when the addition of acrylamide was 4%, 11% water reduction, when the addition of acrylamide was 6%, 21% water reduction.The addition of acrylamide will cause a decline in the early strength of the sample, but later the strength was significantly improved. The best initiator of acrylamide was azobisisobutyronitrile, the best dosage of which was 1%. Temperature effect is significant on the early strength of cement samples with acrylamide, but the optimal cure temperature for 28 days was 35℃. Compressive strength of cement paste was 77Mpa, when polymer cement ratio is 2%. When the concentration of acrylamide was 2%, the sample had high compressive strength; when the concentration of acrylamide was 4%, the sample had high flexural strength in experiments of the 28d mortar.When the concentration of acrylamide was 4%, Corrosion resistance coefficient was up to 1.22, increasing by 11% compared with the blank sample. The addition of acrylamide can improve the corrosion resistance of cement.In the early hydration acrylamide coated on the surface of cement particles and delayed the cement hydration process. However, with the polymerization of acrylamide, the late strength of cement improved. Analyzed by mercury porosimetry, adding acrylamide can increase the density of cement, reduce cement porosity, 20% lower than blank samples, reduce the proportion of harmful holes and optimize the pore distribution.In the experiments of compressive strength by adding calcium acrylate to cement, the amount of 12‰initiator dosage, 10% crosslinking agent, 7% accelerating agent was the best combination for increasing the cement compressive strength. The 3d compressive strength of contenting concentration of 5% calcium acrylate is higher than the blank. The 28d compressive strength of contenting concentration of 5% calcium acrylate is 6% higher than the blank. Contenting concentration of 5% calcium acrylate has high compressive strength and high Flexural strength. In experiments of the 28d mortar, Calcium acrylate and magnesium acrylate compound was added to improve the compressive strength of cement.In the experiments of corrosion resistance test by adding calcium acrylate to cement, the 8‰initiator dosage, the amount of 12% crosslinking agent, the amount of 7% accelerating agent, the corrosion resistance of cement is highest performance. Corrosion resistance factor is 1.2 and increased by 20% compared with the blank sample.By analysising the microscopic structure of cement, calcium acrylate can form the network structure in cement stone, and form a good interfacial bonding with cement. This can increase the density of cement, reduce cement porosity. Analyzed by mercury porosimetry, cement porosity of the cement with 5% calcium acrylate was 36.7% lower than the blank sample, the proportion of harmful holes was reduced and the pore distribution was optimized.?...