Cementitious material based on portland cement and ground granulated blast furnace slag for ground improvement of construction sites in the Mekong Delta

Abstract

This paper presents the results of a study on the selection of binder compositions based on Portland cement combined with ground granulated blast furnace slag (GGBFS) and gypsum for ground improvement using the deep mixing method (cement deep mixing – CDM) and shallow stabilization for road base and foundation works. The study focuses on weak and aggressive foundation soils in the Mekong Delta region. The binder compositions were determined through experimental investigations using three representative types of foundation soils (clayey sand, sandy clay, and high-plasticity clay) collected from expressway construction projects in the Mekong Delta region. Unconfined compressive strength (UCS) was evaluated at curing ages of 3, 7, 28, and 91 days, while durability performance was assessed through immersion in natural seawater up to 6 months. The results show that, relative to soils stabilized with ordinary Portland cement (PC40), the selected binder system—comprising PC40 combined with 55–65% GGBFS and 3–5% gypsum—resulted in a 28-day UCS increase of approximately 1.6 to 2.3 times. The stabilized soils with this binder also exhibited significantly improved durability when immersed in seawater. No cracking or failure was observed after 6 months of immersion, whereas the samples stabilized with ordinary Portland cement showed initial cracking after 3 months and complete failure after 6 months.