Study On Performance Of Basalt Fiber-reinforced Fly Ash Concrete

Fly ash concrete with low heat of hydration, good liquidity, and other advantages, was usually used for mass concrete and concrete pumping project. But, fly ash concrete also has some flaw, such as low early strength, initial drainage of water fast, easy to drier-shrink if inappropriate for the conservation and so on. Research and application shows that the fibers can improve the toughness of concrete, reduce the contraction, restrain the crack generation, and improve the durability of concrete. The performance of the basalt fiber reinforced fly ash concrete was studied in the dissertation on the basis of comparing the properties of fiber common used in the concrete and analysis of the characteristics of a variety of fiber reinforced concrete. The experiments of cube compressive strength, split tensile strength, axis compressive strength, static compression modulus of elasticity, bending strength were conductd and the effects of different content and different aspect ratio of basalt fiber on the mechanical properties of fly ash concrete were studied. The results showed as follows:(1). When the fiber volume content during 0.08% to 0.3%, the compressive strength of fly-ash concrete with 18mm length basalt fiber changed ambiguous, and that of 12mm length basalt fiber is lower a little than the plain fly ash concrete.(2). The basalt fiber can improve the cleave strength of fly-ash concrete using the mix design method of equal volume fiber replaceing the fine aggregate and the effect of enhanceing of 18mm (l ) fiber is better than tnat of 12mm (l ) fiber. When 0.3% volume content, the cleave strength of fly ash concrete with 18mm (l ) basalt fiber increased 22.2 % and that of 12mm (l ) basalt fibers increased 12.4 %.(3). The ratio of tension strength and compression strength of basalt fiber fly ash concrete increased with the basalt fiber content increased, and the increasing extent of the 18mm (l ) basalt fibers is better than that of 12mm (l ). When the fiber volume content is 0.3%, the ratio of the tension strength and compression strength of 18mm (l ) basalt fiber increased 18.2% compareing that of plain fly-ash concrete and that of 12mm (l ) basalt fiber increased 14 %.(4). Basalt fiber can improve the early strength of the fly ash concrete. The experimental results showed the cleave strength of fiber fly ash concrete strength increase more obviusly before 7 days and it increased slower during 7th day to 28th day correspondingly.(5). The effect of the Basalt fiber to static compression modulus of elasticity is not obvius when the fiber content is low. But the basalt fiber can improve the capacity of deformation of the concrete.(6). At the same water-cement ratio, the effect of the basalt fiber to rubble fly ash concrete is better than that of gravel concrete. Several defferent mix design motheds were introduced and the characteristic of the mothed were analyszed at the same time. And the research showed that the mix design method of equal volume fiber replaceing the fine aggregate have several advantages, such as calculating simple, operability good and the strength of the concrete controling easy.Basalt fiber fly-ash concrete is not only hydration heat low but also has the excellent capability to resisting the crack extending, so it has good appling prospects as the civil engineering material. About how to further optimize the parameters of the fiber to strengthen the effect of basalt fiber in the concrete and the durability of basalt fiber fly ash concrete, it will be studied further.