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The aim of this work was to study the compressive strength and microstructure of alkali – activated slag mortar (AAS mortar) under different curing methods. Granulated blast furnace slag (GBFS) was activated by the combination of sodium silicate liquid (Na 2 SiO 3 ) and sodium hydroxide (NaOH) with a silicate modulus (a SiO 2 / Na 2 O weight ratio) of 1 and different Na 2 O concentrations of 4, 6, 8 % by slag weight. AAS mortar specimens were cured in the ambient condition (20 ± 5 °C, 60 ± 5 % RH) (RH: Relative humidity), in a dry oven at 80 °C, and in the saturated limewater at 80 °C for 24 hours. After curing, the specimens were kept in the ambient condition until the time of testing. Scanning electron microscopy (SEM) was used to assess the mortar microstructure. The results revealed that the Na 2 O concentration of alkaline solution and curing method significantly affected the compressive strength of AAS mortar. Curing in the saturated limewater at the high temperature was found to be effective in promoting the mortar strength at later ages.

Clay, which was excavated from the river, was difficult to reuse because of the massive property changes when changing its water content. When being saturated, the clay becomes looser and softer, inducing a significant reduction in the bearing capacity. To improve those disadvantages, the clay was reinforced by the nonwoven geotextile with a sandwich sand layer. Using the California Bearing Ratio (CBR) tests, the reinforced clay’s bearing capacity behavior with a sand cushion under soaking condition was investigated. The result reveals that the sandwich sand layer significantly improved the CBR value of the reinforced riverbed clay. After 96 hours of soaking, the CBR value of reinforced specimens was as high as 1.5-2.8 times that of the un-reinforced specimen. Regarding the bearing capacity reduction after soaking, the CBR value of unreinforced riverbed clay was less than 3%, which reduced up to 73.1% of its bearing capacity before soaking. In contrast, the CBR reductions of reinforced specimens were varied from 42.2-60.8% depending on the thickness of the sand layer. When increasing the sand height, the CBR value went up, especially for soaking specimens. The optimal dry mass ratio between sand and soil was 0.1 in other that the CBR got the highest value.