Research On Homogeneity Of Lightweight Concrete

The rising of lightweight aggregate is a big problem in research of lightweight aggregate. The rising of lightweight aggregate can make the homogeneity of concrete be bad. So the performance hardened concrete will be bad. It can influence the popularization of the lightweight aggregate that scholar in and the problem was paid more attention to in our country. The evaluation and controlling of the homogeneity of lightweight aggregate concrete are always the problem to those who have been always researching on it. They always notice the influence of the homogeneity to hardened concrete without knowing the mechanics of it. So I study on this problem.The device were designed by myself to evaluate the homogeneity of concrete. We have researched the factors that influenced the homogeneity of concrete that include the lightweight aggregate, W/C, admixture and vibrating time. We have also studied on the influence the homogeneity of concrete to the strength and the permeability of the concrete. The result indicate that the lightweight aggregate with normal shape are easy to control than that with globular shape.The homogeneity of concrete can be improved by prewetting the ceramisite agitator, and should shorten vibrating time. We use admixture to improve the homogeneity of concrete and the result indict that the effect is good. The and polyacry lamide is good to improve the homogeneity of concrete that better than carboxyl. But carboxyl methyl cellulose have better effect when it was use with airentrainer. Methyl cellulose also have good effect but it entrained much air that is no good to concrete. Fly ash is good to the homogeneity of concrete which have better effect if it was used with airentrainer. The polypropylene fibre have the better effect to concrete that the flowability is not too big than that is big. The polyacrylonitrile have no use to improve the homogeneity of concrete. The homogeneity of concrete have bad effect to compression strength, but the effect to chloride ion coefficient of diffusion is not obvious. For concrete used generality, if it's homogeneity is acceptable (k≤7%), the percentage of lost of the compression strength will lower than 10%. For deep-pouring concrete, only if...