定向钢纤维增强水泥基复合材料干燥收缩性能数值模拟研究

Numerical simulation of drying shrinkage properties for aligned steel fiber reinforced cementitious composites

干燥收缩是引起水泥基复合材料开裂的主要原因之一,掺加钢纤维可以有效约束水泥基复合材料的收缩、提高抗裂性。显然,规律性定向分布的钢纤维对基体的收缩约束作用与随机乱向钢纤维不同。为此,考虑钢纤维方向性对基体收缩的影响,通过数值模拟研究了定向钢纤维增强水泥基复合材料的干燥收缩性能。数值模拟结果表明,ASFRC的干燥收缩应变明显小于SFRC,如钢纤维体积掺量分别为0.8%、1.0%、1.2%、2.0%的钢纤维增强水泥基复合材料试件,经过360 d干燥,ASFRC的干燥收缩应变比SFRC分别减小19.5%、21.8%、29.6%、35.0%。钢纤维在定向方向上对基体的收缩约束作用大幅度提高,有效减小了水泥基复合材料因失水产生的干燥收缩。

Drying shrinkage is one of the main reasons which cause the dehiscence of cementitious composites.Mixing steel fibers in to it is conducive to restraining the shrinkage of cementitious composites effectively and enhancing the crack resistance.Obviously,the restriction effect varies from the steel fibers distribute aligned and regularly to those distribute in random way.For this reason,the drying shrinkage performance of ASFRC has been studied through numerical simulation.As the result of numerical simulation shows,the drying shrinkage strain is obviously less than which of SFRC.After 360 d drying,the shrinkage strain of specimen of ASFRC mixed with steel fibers in volume of 0.8%,1.0%,1.2%and 2.0%will decrease by 19.5%,21.8%,29.6%and 35.0%,compared with SFRC.There are two reasons can demonstrate why directional steel fiber has capacity to restrain the cementitious composite.The effect of steel fiber restraining matrix shrinkage in the aligned directionis enhanced in a large extent and the drying shrinkage caused by moisture loss of cementitious composite is effectively decreased.