疏水性侵蚀抑制剂对水泥水化影响及作用机理分析

Effect and Mechanism Analysis of Carboxylic Acid Type HydrophobicAgent on Cement Hydration

疏水性侵蚀抑制剂使混凝土具有优异疏水效果,抑制了侵蚀性环境中介质传输,然而其作用机制尚未明确。本文对水泥浆体在不同疏水性侵蚀抑制剂(CAHA)掺量下的水化行为进行了研究,探究了其对水泥水化放热、水化物相、表面接触角、抗压强度等性能的影响。研究结果表明,CAHA降低了水泥浆体第一水化放热峰并延缓水泥水化,在水化前期抑制了钙矾石和氢氧化钙的生成,这种抑制作用在高掺量下更为显著。CAHA一定程度上降低了砂浆早期抗压强度,对28 d抗压强度影响并不明显。CAHA显著降低砂浆吸水率并使其具有疏水性。通过比对,推荐CAHA最佳掺量为胶凝材料质量的6%,此时水泥砂浆抗压强度损失较小且抗侵蚀性能明显提升。

The hydrophobic corrosion inhibitor makes the concrete have an excellent hydrophobic effect and inhibits the medium transmission in the corrosive environment.However,the mechanism of action is not clear.In this paper,the hydration behavior of cement paste with different content of carboxylic acid type hydrophobic agent(CAHA)was studied,and its effects on the hydration heat,hydrate phase,surface contact angle,and compressive strength of cement were investigated.The results show that CAHA reduces the first hydration exothermic peak of cement paste and delays the hydration of cement.In the early stage of hydration,CAHA inhibits the formation of ettringite and calcium hydroxide,which is more significant at high dosage.CAHA reduces the early compressive strength of mortar to a certain extent and has no obvious effect on 28 d compressive strength.CAHA significantly reduces the water absorption of mortar and makes it hydrophobic.Through comparison,the optimum dosage of CAHA is recommended to be 6%of the mass of cementitious material,at which time the loss of compressive strength of the cement mortar is smaller and the erosion resistance is significantly improved.