Investigation of Compacted Clay Cover Modified by New Water Retaining Agents

Abstract

The gas diffusion/permeation and solution permeation dominant channels formed by desiccation cracks in compacted clay have become a significant hidden danger of environmental pollution. This study used clinoptilolite and sodium polyacrylate(Na-PAA) as a new water-retaining agent to enhance the water-holding capacity and impermeability. The primary and secondary order and optimal combination of all influencing factors, such as the replacement content of clinoptilolite (A), the content of Na-PAA (B), mixing moisture content(C), dry density(D) and curing age(E), were studied by orthogonal experimental. The results reveal that (1) The traditional analytical method and the Analytic Hierarchy Process (AHP) to obtain the optimal combination of unified A4B4C4D4E3, that is, replacement content of clinoptilolite, the content of Na-PAA, the mixing moisture content, dry density and curing age was 25%, 1.2%, 23%, 1.8g/cm3, and 14d, respectively. (2) For the multi-index test, the traditional analytical method just can obtain the factors order of a single index. And it is difficult to determine the comprehensive degree of each factor to multi-index. (3) The AHP to the quantitative calculation of each factor level index weights, the influence of all the factors on the multi-index integrated primary and secondary order. (4) the verification results show that we need to adjust the best combination of dry density ρd≥0.90×ρdmax, moisture content w=OMC+(0-4%).