Expansion evaluation of a soil of the municipality of Paulista-PE improved with lime
ABSTRACT The volume variation of the expansive soils due to the change of water content causes socioeconomic and environmental damage to geotechnical engineering works. Two basic requirements are needed for a soil to exhibit expansiveness, one intrinsic and the other extrinsic. The first is related to the soil mineralogical com- position, texture and structure and the second with the behavior of climate, the volume and the movement of groundwater, the vegetation and the anthropic occupation. The addition of lime to the expansive soil im- proves the geotechnical properties of the mixture. The lime has physical-chemical interactions with the ex- pansive soil capable of stabilizing the volume variation. Several buildings under construction in the State of Pernambuco are located in areas of occurrence of expansive soils. The effect of lime treatment on the proper- ties of Paulista expansive soil was investigated, comparing the behavior of natural soil and soil mixed with lime in the proportions of 3%, 5%, and 7% by weight. Physical, chemical and mineralogical characterization tests (by thermogravimetry (TG) and X-ray diffractometry), free expansion and expansion stress were carried out. The natural soil presented high expansiveness. The determination of the expansion voltage was influ- enced by the voltage trajectory followed during the test. The addition of lime to the soil caused an aggrega- tion or flocculation of the particles and a reduction in the plasticity index. The addition of 5% of hydrated lime to the soil of Paulista stabilized in relation to the free expansion and the expansion tension.