冻融循环对轻质填料抗压强度的影响

Abstract

A lightweight fillers studied include waste foundry sand, fly ash, expandable polystyrene (EPS) beads. Utilization of lightweight fillers as industrial solid wastes is not only beneficial to environment protection, but also takes advantages of low density, thermal insulation and anti-freeze/thaw behavior that the fillers possess, which put the materials favorably applicable to various backfilling infrastructure works at cold regions. Unconfined compressive strength tests were conducted on 13 sets of samples with different mix proportions that were subjected to changeable freeze-thaw cycles. The purpose is to analyze the compressive strength and deformation characteristics of the lightweight fillers under freeze-thaw conditions. It is found that materials maintain acceptable mechanical behavior after subject to freeze-thaw cycles. Mixture components play different roles in affecting the strength characteristics of materials. Cement component clearly enhances anti-freeze capability of the materials. Components of EPS and fly ash may improve the freeze-thaw resistance of the materials. Water is the main source causing freeze-thaw failure. Therefore, it is suggested that water content be prudentially controlled as long as adequate water supply for cement hydration is provided. The mechanism of materials' freeze/thaw resistance is also discussed. = 通过对不同配合比的13组试样在不同冻融循环次数下的无侧限抗压强度试验,研究了冻融循环对轻质填料抗压强度与变形特性的影响.结果表明,轻质填料经历冻融循环后仍具有良好的力学性能,各组分对轻质填料抗冻融特性的影响程度不同,掺加水泥可有效抵抗冻胀力,EPS颗粒和粉煤灰在掺量适中的情况下,可显著提高轻质填料的抗冻融性能,水分是造成轻质填料冻融破坏的主要因素,在满足水泥水化所需水分的前提下,寒区工程中应用轻质填料需适当降低含水率.另外,在分析不同控制强度下轻质填料冻融破坏特点的基础上,分析了该轻质填料抗冻融破坏机理.