Modelling of Soundness Property-Coarse Aggregates

In the past several attempts have been made to develop a relationship between the compaction characteristics and the CBR of different groups of soil. Large scale road constructions are taking place over the length and breadth of India due to adoption of various intensified activities in road construction in India like PMGSY, etc. As a result huge quantity of aggregate material is being needed for the constructions of sub-base in most of the situations. For that aggregates are collected from extensive areas. Such aggregates may have larger variations in their engineering properties due to variety of reasons. But proper estimation of variation in properties of the materials used for construction work can only ensure the satisfactory performance of the constructed road with cost effectiveness. The soundness property test result is one of the important parameter used effectively for such assessment. But in practice only limited number of such tests could be performed for evaluating these engineering properties because of high cost and time required for testing and as a result, it is difficult to reveal detailed variation in the soundness values to enable rational, economic and also safe construction. One of the most important property of aggregates is the resistance to weathering action or soundness .The stone aggregates should retain the strength characteristics and should not disintegrate under adverse weather conditions including alternate dry and wet/freeze-thaw cycles or in other words the aggregates should have enough durability or resistance to weathering action. In absence of adequate information from performance studies, a laboratory test simulating accelerated weathering condition is created to judge durability or soundness of aggregates. Soundness test takes at least 10 days for completion. In such cases if the estimation of the soundness value could be developed on the basis of some tests which are quick to perform, less time consuming and cheap, then the process will help the constructors enormously. In this view an attempt has been made to develop a correlation between the various physical characteristics of aggregates from different sources across Kashmir valley and adjoining areas in J&K, so as to develop a mathematical model depicting relationship between other physical characteristics & soundness property of aggregates. Using various softwares (such as NLREG-Nonlinear Regression and Curve Fitting; MRA&F; XLSTAT), a general relationship between the soundness property and other various characteristics of aggregates (from J&K) has been developed. In this study comparison of soundness property with various other properties of aggregates by the help of mathematical models and validation of the devised mathematical models has been made.