高吸水树脂对混凝土水化及强度的影响

高吸水树脂(Super-absorbent polymer,SAP)作为混凝土内养护材料可有效抑制混凝土自收缩,提高混凝土抗裂性,但其对混凝土是否具有负面影响有待研究。利用XRD和DTA-TG研究了不同SAP掺量净浆在不同养护龄期的水化产物量,并测试其抗压强度,定量分析高吸水树脂对混凝土水化和强度的影响。实验结果表明:掺加SAP会延缓混凝土早期(0~7d)的水化反应,降低混凝土的抗压强度,但对混凝土中后期(7~28d)水化的进行及强度发展的影响不大。当高吸水树脂的掺量为1kg/m~3(占胶凝材料的质量分数为0.2%)和1.5kg/m~3(占胶凝材料的质量分数为0.3%)时,混凝土28d抗压强度可达基准组的100%和96%,56d抗压强度可达基准组的107%和96%。针对C50混凝土,推荐掺量为1kg/m~3。

Effect of Super-absorbent Polymer on Hydration and Compressive Strength of Concrete

Super absorbent polymer (SAP) as a kind of internal curing materials can effectively inhibit the autogenous shrinkage and prevent crack formation .However ,it remains to be studied whether SAP has a negative impact on concrete .In this paper ,the hydration products of paste incorporated by different content of SAP were studied by XRD and DTA-TG ,and mechanical properties were tested after standard curing to the different ages .The influence of SAP on hydration and compressive strength of concrete was studied quantificationally .Results indicated that SAP could delay the early hydration on concrete (0—7 d) and the compressive strength of concrete decreased as well .After 7 days curing ,the influence of SAP on hydration and compressive strength of concrete was negligible .When the addition of SAP was 1 kg/m3 (the mass percentage of super absorbent polymer in cementitious material was 0.2％ ) and 1.5 kg/m3 (the mass percentage of super absorbent polymer in cementitious material was 0.3％ ) ,the compressive strength of concrete with SAP was 100％ and 96％ of the concrete without SAP at the age of 28 days .After 56 days curing ,the compressive strength of concrete with SAP was 107％ and 96％ of the concrete without SAP .For C50 concrete ,the recommended content of SAP is 1 kg/m3.