Experimental study of mechanical and microstructural properties of Lianyungang soft soil solidified by granulated blast-furnace slag-magnesium oxide

CHEN Jinhong;HE Yaoyao;HU Yafeng;Wuchang Shouyi University;School of Civil Engineering,Nanjing Forestry University;

MgO-GGBS;;solidification;;soft soil;;mechanical properties;;microstructure

In order to investigate the mechanical property influence of granulated blast furnace slag,magnesium oxide and ordinary portland cement on solidified soft soil,ordinary portland cement,granulated blast-furnace slag and magnesium oxide were used to solidify Lianyungang soft soil. The differences in the mechanical properties of ordinary portland cement,granulated blast-furnace slag and magnesium oxide solidified Lianyungang soft soil were examined using water content test,unconfined compressive strength test and permeability test. Changes in the soil microstructural properties were interpreted by scanning electron microscope observations and mercury intrusion porosimetry tests. Results indicated that ordinary portland cement and granulated blast-furnace slag-magnesium oxide had an efficient effect on soft soil. The unconfined compressive strength and hydraulic conductivity were improved significantly with the increase in cement dosage.In addition,the unconfined compressive strength and hydraulic conductivity of ordinary portland cement solidified soft soil were worse than ground granulated blast-furnace slag and magnesium oxide solidified soft soil at the same reactant dosage. Mercury intrusion porosimetry test results showed that the pore volumes of ordinary portland cement,granulated blast-furnace slag and magnesium oxide solidified soil were decreased significantly with the increase in cement dosage.The pore volume whose diameter was larger than 1. 0 μm in ordinary portland cement solidified soft soil was changed. However,the pore volume whose diameter was larger than 0.1 μm in granulated blast-furnace slag and magnesium oxide solidified soft soil was changed. Scanning electron microscope test results showed that a larger aggregation was formed with a smaller void space in soils as the ordinary portland cement and granulated blast furnace slag-magnesium oxide dosages were increased. However,the degree of consolidation of granulated blast furnace slag-magnesium oxide solidified soil was better than ordinary portland cement solidified soil. The differences in mechanical properties of ordinary portland cement and granulated blast furnace slag-magnesium oxide solidified soil was attributed to the differences in pore volume and microstructure features in solidified soil.