不同缓凝剂对水泥超长缓凝作用与水化特性的影响

Effect of Different Retarders on the Super Retarding Action and Hydration Characteristics of Cement

研究了羟基乙叉二膦酸(HP)、蔗糖(ZT)和葡萄糖酸钠(PN)3种缓凝剂对水泥净浆凝结时间和抗压强度的影响,并利用水化热测试、XRD、热重等手段分析对延缓水泥水化的影响机理。结果表明,随着3种缓凝剂掺量的增大,凝结时间逐渐延长,掺0.3%和0.4%的ZT出现不凝的现象,掺0.3%和0.4%的PN和HP均达超缓凝,7 d时无强度,14 d和21 d强度明显低于空白组(KB),但28 d强度接近空白组,到90 d则均高于空白组。HP的超缓凝作用使水泥的水化程度缓慢降低的效果最明显,其水化产物中的AFt略低于KB的,而AFm量极少,远低于KB的,CH以及包括C-S-H凝胶在内的非晶相接近KB的。与PN相比,HP对水泥的水化抑制效果较好,HP的水化产物AFt量略低于PN的,CH以及包括C-S-H凝胶在内的非晶相与PN接近。

The effects of three retarders of HP,ZT and PN on the setting time and compressive strength of cement pastes were studied,the influence mechanism was analyzed by means of isothermal calorimetry,XRD and TG.The results show that with the increase of dosage of different retarder,the setting time gradually extends.When the ZT content is 0.3%and 0.4%,no solidification occurre.The PN and HP mixed with 0.3%and 0.4%both reach super retarding setting,and have no compressive strength at 7 d,the compressive strength is significantly lower than blank group(KB)at 14 d and 21 d,but it is close to blank group at 28 d,and higher than blank group at 90 d.The effect of HP’s super retarding action on slowly decreasing the hydration degree of cement is most obvious.AFt in hydration products is slightly lower than KB,while AFm is much lower than KB,CH and amorphous phase including C-S-H gel are close to KB.The hydration inhibition effect of HP is better than that of PN,and the amount of AFt is slightly lower than that of PN,CH and amorphous phase including C-S-H gel are close to that of PN.