不同改性再生粗骨料对PVA纤维混凝土抗压及劈拉强度的影响

Effect of different modified recycled coarse aggregate on compressive strength and splitting tensile strength of PVA fiber reinforced concrete

再生粗骨料自身的缺陷影响了再生混凝土的基本性能。为了改善再生粗骨料的物理特性,利用单因素试验的方法分别研究了盐酸溶液、硅酸钠溶液、聚乙烯醇溶液、硅烷偶联剂溶液、水泥外掺粉煤灰混合浆液对再生粗骨料进行的一次改性,同时研究了在盐酸溶液对再生粗骨料进行一次改性的基础上再利用其他四种溶液或者混合浆液对其进行第二次改性试验,并且使用九种不同改性再生粗骨料制备PVA纤维再生混凝土,对比不同改性再生混凝土的力学性能。试验结果表明:九种改性方法均可改善再生粗骨料的表观密度与压碎指标,对混凝土力学性能的影响是不同的,除使用水泥外掺粉煤灰混合浆液的一、二次改性方法,其余改性方法均可提高PVA纤维再生混凝土的抗压及劈拉强度,其中利用5%盐酸溶液进行一次改性能够最大程度地提高再生混凝土抗压及劈拉强度。

The defects of recycled coarse aggregate affect the basic properties of recycled concrete.In order to improve the physical properties of recycled coarse aggregates,the modification of recycled coarse aggregate by hydrochloric acid solution,sodium silicate solution,polyvinyl alcohol solution,silane coupling agent solution and cement mixed with fly ash slurry is studied by single factor test.At the same time,the second modification test is carried out by using of four other solutions or mixed slurries on the basis of hydrochloric acid solution modified the recycled coarse aggregates,and the PVA fiber recycled concrete is prepared with nine different modified recycled coarse aggregates.The mechanical properties of different modified recycled concrete are compared.The results show that all the nine modification methods can improve the apparent density and crushing index of the recycled coarse aggregate.Different modification methods of recycled coarse aggregate have different effects on the mechanical properties of concrete.Except for the first and second modification methods with cement and fly ash mixed slurry,the other modification methods can improve the compressive and splitting tensile strength of PVA fiber recycled concrete.The compressive strength and splitting tensile strength of recycled concrete can be improved to the greatest extent by using 5%hydrochloric acid solution to modify the recycled coarse aggregates.