高性能混凝土胶凝材料体系开裂敏感性试验研究

采用净浆圆环约束试验研究高性能混凝土胶凝材料体系的开裂敏感性,试验考虑的主要参数包括:水泥细度,水灰比,粉煤灰品种、掺量,外加剂的品种、掺量等.试验结果表明,水泥细度、水灰(胶)比对胶凝材料体系的开裂敏感性有显著影响,水泥细度越大,水胶比越低,胶凝材料体系越容易开裂;在同样的水胶比下,以粉煤灰等量替代水泥,总体上可以改善胶凝材料体系的开裂敏感性;不同的粉煤灰的掺量、来源对胶凝材料体系开裂性能的影响程度有很大差异;在不同的水胶比下,粉煤灰掺量的影响也不一致;外加剂有增大胶凝材料体系的开裂敏感性的趋势,其影响随着品种、掺量而不同.提出了减小高性能混凝土开裂敏感性的建议.

Experimental studies on cementitious systems cracking sensitivity of high performance concrete

Experimental study on cracking sensitivity of high performance concrete(HPC) cementitious systems by ring test is conducted.The main parameters considered in this paper are fineness of the cement,water to cementitious ratios,type and content of fly ash,type and dosage of superplasticizers and so on.The results indicated that with the increase of the cement fineness and the decrease of the water to cementitious ratio,the cracking age of the ring speciemens shortened significantly;fly ash will help to improve the cracking sensitivity of cementitious systems,while fly ashes of different content,different source and in different water to cementitious ratios have different effect extents;superplasticizers are prone to increase the cracking risk of the ring specimens,but the extents are different depending on the type and dosage.Based on the experimental results,advices are given to improve the cracking resistance of HPC mixtures.