偏高岭土对聚合物改性PC-CSA-FGD防腐砂浆性能的影响

Influence of Metakaolin on Performances of Polymer Modified PC-CSA-FGD Anti-corrosion Mortar

摘要:

本文研究了偏高岭土（MK）对聚合物改性硅酸盐水泥-硫铝酸盐水泥-脱硫石膏（PC-CSA-FGD）三元胶凝体系防腐砂浆（简称防腐砂浆）凝结时间、力学性能、抗硫酸盐侵蚀性能、抗氯离子侵蚀性能、水化产物和孔结构的影响.结果表明：随着MK掺量的增大，防腐砂浆的凝结时间逐渐缩短，掺30% MK防腐砂浆的初凝时间和终凝时间较初始值分别缩短了28、47 min；当掺量较低时，MK能提高防腐砂浆的力学性能、抗硫酸盐侵蚀性能和抗氯离子侵蚀性能，掺10% MK防腐砂浆的90 d抗折强度和抗压强度分别为13.6、73.4 MPa，氯离子扩散系数仅为0.30×10^-12 m²/s，这与MK能优化孔结构、降低水化产物氢氧化钙和钙矾石含量、反应生成更多水化硅酸钙凝胶和水化硅铝酸钙凝胶有关；MK在防腐砂浆中的掺量不宜超过20%，以10%最佳.

Abstract:

The effects of metakaolin on the setting time， mechanical properties， resistance to sulfate and chloride attack， hydration products， and pore structure of polymer modified anti-corrosion mortar（anti-corrosion mortar） with Portland cement-calcium sulphoaluminate cement-flue gas desulfurization gypsum （PC-CSA-FGD） ternary binder systems were investigated. The results show that with its content increase， metakaolin can reduce the setting time of anti-corrosion mortar， with the maximum reduction of the initial and final setting time to be 28 and 47 minutes at 30% of metakaolin content. At low content， metakaolin can improve the mechanical properties including flexural strength， compressive strength and tensile bond strength， the sulfate resistance and the chloride penetration resistance of the anti-corrosion mortar. At 90 d， the flexural and compressive strengths reach 13.6 MPa and 73.4 MPa respectively， and the chloride diffusion coefficient is only 0.30×10^-12 m²/s at 10% of metakaolin content. It is mainly due to that metakaolin can optimize the pore structure， decrease the content of portlandite and ettringite， and increase the content of hydrate calcium silicate and hydrated calcium aluminosilicate gels. Comprehensively， the content of metakaolin in the anti-corrosion mortar should not exceed 20%， with the optimal content to be 10%.