Evaluations of pavement soil subgrades for the purpose of design are mostly based on empirical methods such as the CBR, California soil resistance method, etc. The need for the application of theory and the evaluation of subgrade strength in terms of the modulus of elasticity in place of empirical methods is essential for rational design techniques. In this investigation, the maximum deflection of the pavement and the shape of the deflected basin were utilized to determine the modulus of elasticity of the subgrade. The shape of the deflected basin is defined by the word "spreadability", which is in turn defined as the average deflection as a percentage of the maximum deflection. An evaluation chart was developed. By means of this chart the modulus of elasticity of the subgrade can be determined if the maximum and four other deflections in the deflected basin are known. The same principle could be applied to develop a similar type of evaluation chart based on the information of the deflected basin collected by any other agency.
In this investigation, the optimum structural strength contributed by a material to the overall strength of the pavement was studied for cases applica...
In this investigation the changes in the subgrade moisture content under five road pavements ranging in age from new to about ten years old were deter...
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United States Department of Transportation
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