依据材料与构件的受弯性能综合评价ECC的控裂性

为了研究国产的工程水泥基复合材料(Engineered Cementitious Composites,ECC)和普通聚乙烯醇(Polyvi-nyl Alcohol,PVA)纤维混凝土对结构增韧和控裂的效果,分别采用材料试验和构件试验进行研究。通过四点弯曲试验,发现ECC的峰值荷载和峰值荷载对应的拉应变要远远大于普通混凝土、PVA纤维混凝土,而且ECC起裂以后,裂缝宽度较小,且发展较慢,控制较好;采用不同高度的ECC、PVA纤维混凝土作为钢筋混凝土梁底保护层,发现1/4h ECC对钢筋混凝土增韧的效果最好,且裂缝宽度为0.2mm时,1/4h ECC的承载能力比普通钢筋混凝土提高1.6倍,峰值荷载比普通钢筋混凝土提高约12%;同时发现,在相同荷载作用下,采用ECC作为梁底保护层时,裂缝宽度比钢筋混凝土小,且可以有效地控制裂缝宽度的快速增长,间接提高结构的耐久性。

Evaluation and Research on Crack-controlling Bahavior of ECC According to Bending Performance of Materials and Components

In order to research the toughening and crack control effect on structure of the domestic ECC and ordinary PVA fiber reinforced concrete,the material and construction member test were carried out.By the four points bending experiment,it is found that the peak load and the corresponding tensile strain of ECC are much great than that of ordinary concrete and PVA fiber reinforced concrete.And crack width can be better controlled.The crack width is smaller and spreads slower than ordinary reinforced concrete.Using the ECC,PVA fiber concrete as the bottom protecting layer of the reinforced concrete beam of different height,it is found that a 1/4h ECC has the best toughening effect.And when crack width reached 0.2 mm,the load-bearing capacity of 1/4h ECC increases 1.6 times than that of ordinary reinforced concrete,the peak load increases bout 12%.And then,the crack width is smaller than reinforced concrete in the same load when the ECC is used as beam bottom layer.And ECC can effectively control the rapid growth of crack width,indirectly improve the durability of structures.