BEARING CAPACITY OF SHALLOW FOOTING ON SOFT CLAY IMPROVED BY COMPACTED FLY ASH

Abstract

Low bearing capacity of weak soil under shallow footings represents one of construction problems.Kaolin with water content converges to liquid limit used to represent the weak soil under shallowfooting prototype. On the other hand, fly ash, which can be defined as undesirable industrial wastematerial, was used to improve the bearing capacity of the soft soil considered in this research. The softsoil was prepared in steel box (36×36×25) cm and shallow square footing prototype (6×6) cm wereused .Group of physical and chemical tests were conducted on kaolin and fly ash. The soft soil wasimproved by a bed of compacted fly ash placed under the footing with dimensions equal to that offooting but with different depth ratios. The results show that there is a noticeable improvement in thebehavior of footing when improved by compacted fly ash. The improvement showed a decrease insettlement and increase in bearing capacity. The improvement ratio in bearing capacity was calculatedby comparing the ultimate bearing capacity value when testing the kaolin alone with its value of kaolinimproved with compacted fly ash at the same value of eccentricity. It is important to note thateccentricity values were chosen according to the rule of middle third of footing base(i.e.,e≤B/6). Theimprovement ratio was about (130%) in average value, that represent a good ratio of improvement