Effects of Environmental Factors on Construction of Soil–Cement Pavement Layers

Abstract

The specific objectives of this research were to quantify the effects of certain environmental factors on the relative strength loss of soil–cement subjected to compaction delay and to develop a numerical tool that can be easily used by engineers and contractors for determining a maximum compaction delay time for a given project. These objectives were addressed through extensive laboratory work and statistical analyses. The laboratory work involved testing an aggregate base material and a subgrade soil, each treated with two levels of cement. Environmental factors included in the experimentation were wind speed, air temperature, and relative humidity; three levels of each factor were evaluated in combination with three compaction delay times. The primary response variables in this research were relative compaction and relative strength. The findings indicate that relative strength is sensitive to variability among the selected independent variables within the ranges investigated in this research, while relative compaction is not. Inferring relative strength from relative density is therefore not a reliable approach on soil–cement projects. Consistent with theory, higher wind speed, higher air temperature, lower relative humidity, and higher compaction delay time generally result in lower relative strength. With the nomographs developed in this research, the maximum delay time permitted for compaction of either a base or subgrade material similar to those tested in this research can be calculated. Knowing in advance how much time is available for working the soil–cement will help contractors schedule their activities more appropriately and ultimately produce higher-quality roads.