多孔饱水骨料内养护对混凝土抗裂性能及强度影响试验研究

Experimental Study on Effect for Internal Curing of Porous Saturated Aggregate on the Crack Resistance and Strength of Concrete

针对混凝土收缩开裂现象,通过改变多孔骨料的含水率及掺量,进行平板开裂试验,研究多孔饱水陶粒骨料内养护对混凝土抗裂性能及强度的影响,并结合绝热温升试验及内部湿度相对变化情况,探究多孔饱水骨料内养护对提高混凝土抗裂性能的微观作用机理,试验结果表明:使用多孔饱水陶粒骨料代替部分砂石骨料,可减少混凝土早期塑性收缩,降低大体积混凝土内部水化温升,有效降低混凝土早期的收缩开裂;多孔饱水陶粒骨料能改善混凝土试件胶凝材料水化引起的内部自干燥情形,相对湿度较高,达到内养护目的;多孔饱水骨料取代砂石骨料降低了混凝土的抗压强度,且28d龄期抗压强度降低幅度较大时体积掺量为20%,综合考虑抗裂性能与强度性能,最佳取代率为20%。

In view of the phenomenon of concrete shrinkage cracking,by changing the moisture content of porous aggregate and dosage,the plate cracking test was carried out to study the effect of internal curing of porous water saturated ceramsite aggregate on the crack resistance and strength of concrete.Combined with the adiabatic temperature rise test and the relative change of internal humidity,the micro mechanism of internal curing of porous water saturated aggregate on improving the crack resistance of concrete was explored.The test results show that the use of porous water saturated ceramsite aggregate instead of part of sand and stone aggregate can reduce the early plastic shrinkage of concrete,reduce the internal hydration temperature rise of mass concrete,and effectively reduce the early shrinkage cracking of concrete;porous water saturated ceramsite aggregate can improve the internal self drying caused by the hydration of concrete specimen cementitious materials,with high relative humidity,reaching the goal of internal conservation;The compressive strength of concrete is reduced by porous saturated aggregate instead of sand aggregate,and the volume content is 20%when the compressive strength is greatly reduced in the 28d age.Considering the anti-cracking performance and strength performance,the best replacement rate is 20%.