Effect of fly ash on strength and swelling aspect of an expansive soil

Abstract

Swelling soil always create problems more for lightly loaded structures than moderately loaded structures. By consolidating under load and changing volumetrically along with seasonal moisture variation, these problems are manifested through swelling, shrinkage and unequal settlement. As a result damage to foundation systems, structural elements and architectural features defeat the purpose for which the structures are erected.An attempt to study such unpredictable behavior and through research on how to bring these problems under control form the backdrop for this project work. Pre-stabilization is very effective method in tackling expansive soil. Therefore a number of laboratory experiments are conducted to ascertain host of soil engineering properties of a naturally available expansive soil before and after stabilization. Pre and post stabilized results are compared to arrive at conclusion that can thwart expansive soil problems. Index properties of expansive soil like liquid limit, plastic limit and shrinkage limit with and without fly-ash have been compared. Along with these Atterberg limits, grain size distribution has also determined. The swelling potential of expansive soil is determined with different percentage of fly-ash. For different percentages of fly-ash 1)maximum dry density and 2) optimum moisture contents are found by the proctor compaction test and the comparison graphs are drawn. The strength aspects of expansive soil are determined for soil specimens with different fly-ash concentrations through Unconfined Compression Test and California Bearing Ratio Test and the results are compared through the graphs.The above experimental results are compared among them to obtain a percentage concentration of fly-ash with swelling soil which gives best results for lower value of swelling potential and higher strength.