Strengthening sand column using PFA-cement mixture

Abstract

Soft soils are generally labelled as problematic and weak soil because they have poor resistance to deformation, low permeability, limited bearing capacity and excessive settlement. Thus, improvement of the feeble properties of soft soils can be achieved by adopting suitable ground reinforcement technics. This study introduced the use of Pulverized Fuel Ash (PFA)-cement sand column as one of the solutions strengthen the soft soil. PFA was carefully chosen in this study because of its chemical compositions, strength characteristics and workability that can helping in process of improving the ground. The investigation is based on laboratory experimental work which involved 2 modules of laboratory test. The first test conducted was shear box test where 180 samples of PFA-cement-sand and 180 samples of PFAcement-quarry dust mixed in different proportions and tested for 28 days of curing time. The purpose of this test are to determine the suitable material to be used either sand or quarry dust in process of strengthening of mixture and also to determine the suitable mix design that can providing the optimum value of shear strength. Unconfined compression test (UCT) was carried out as second test. Based on shear box test result, sand has been selected as a material mixed along with PFA-cement. For UCT test, lime, cement and mix of lime-cement are been used in process to determine either cement or lime itself or mix of lime-cement will providing suitable mixture with the optimum strength. 72 samples with various proportions been tested for 28 days of curing time. © 2013 ejge.