纤维特性对砂加气混凝土力学性能和微观结构的影响

砂加气混凝土因其韧性较差,在生产过程中易出现缺棱掉角的现象.通过添加不同长径比和弹性模量的纤维,研究纤维掺量对砂加气混凝土抗压和抗折强度的影响,并借助X射线衍射和扫描电镜分析其微观结构,研究了纤维对砂加气混凝土增韧机理.研究结果表明:聚丙烯纤维和玻璃纤维的最佳掺量均为0.3%,砂加气混凝土的抗压强度分别提高了22.0%和27.8%,抗折强度分别提高了20.0%和26.0%.不同纤维对砂加气混凝土的水化产物含量有一定的影响,但不会生成新相.纤维对砂加气混凝土的增强增韧机理主要在于其能在基体中形成三维网络骨架,通过减缓裂纹尖端的应力集中,减缓或阻止裂纹的扩展.添加两种纤维的砂加气混凝土砌块受力时主要对纤维拔出做功,因此纤维本身的弹性模量对砂加气混凝土强度的影响较小.

Effect of Fiber Properties on Mechanical Properties and Microstructures of Autoclaved Aerated Concrete

Autoclaved aerated concrete is easy to appear the phenomenon of lack of edge drop horn during the production process because of its poor toughness.The effects of fiber content on the compressive and flexural strength were researched by adding fibers with different length-diameter ratio and elastic modulus in autoclaved aerated concrete.The microstructures were determined by X-ray diffraction and scanning electron microscopy analysis.The toughening mechanism of fibers on autoclaved aerated concrete was studied.The results show that the optimum content of polypropylene fiber and glass fiber is 0.3%.The compressive strength of the autoclaved aerated concrete increased by 22.0% and 27.8%, respectively and the flexural strength increased by 20.0%and 26.0%, respectively.The fibers have a certain effect on the hydration products content for the autoclaved aerated concrete, but new phases don't occur.A three-dimensional network skeleton in the matrix is formed when fibers are added in the autoclaved aerated concrete, which slow down or prevent the expansion of the crack by slowing the stress concentration at the crack tip.The main work is to overcome the resistance to pulling out the fibers for autoclaved aerated concrete, so the effect of fibers on the strength of the autoclaved aerated concrete is not related to the elastic modulus of fibers.