Effect And Mechanism Of Admixture To Steel Slag Anti-cracking Dry-mixed Mortar

In the wall thermal insulation system, the performance of anti-cracking mortar has intimate relationships with the polymer admixtures. Various admixtures, with different and unique function and performance, the interaction on the influence of the mortar performance when using together should not be ignored.Unlike traditional anti-crack mortar by adding admixtures or shrinkage compensation materials to make mortar meet anti-cracking performance,this research by using steel slag with expansion and high wear-resisting characteristics to make up mortar, and select the type and content of admixtures by studying the influence of mortar performance due to re-dispersion emulsion powder, cellulose ether and defoamer. The steel slag anti-cracking dry mixed mortar, appropriate for the engineering application for wall insulation system, on the one hand, cut down cost, on the other hand, can save energy and resources, solve the environmental pollution, has a good market prospect.This study select the size and content of steel slag sand at first, then compare the performance of mortar changes due to the changes of type and content of the admixture. Determine its best dosage and their mechanism, function gave the corresponding explanation. Test to determine the appropriate amount and explain their mechanism in mortar.The research shows that:(1) Steel slag particle size in less than 0.6 mm, can replaced with the river sands in 100% to make anti-cracking mortar which can meet the stability requirement. (2)The acrylic re-dispersion emulsion powder by waterproof modification can make dry mixed mortar superior performance. (3) The change of the mortar performance caused by HPMC with different viscosity is similar. The mesh structure of HPMC is the main reason to improve the mortar retention of water and cohesive strength (4) Polyol powder defoamor in the critical point as the admixture of 0.1%. Defoamer can make bubbles burst by reducing the surface energy. (5) Reasonable content of re-dispersion emulsion powder, cellulose ether and defoamor will make the performance of anti-crack mortar improved obviously. The best ratio for these three admixtures is:acrylic re-dispersion emulsion powder is 1.5%, MHPC (40000mPa·s) is 0.3%, defoamor is 0.05%. And the mortar performances can meet the standards.