Mechanical performance and physico-chemical behavior of soilcrete incorporating low-carbon binders

Deep Soil Mixing (DSM) offers a sustainable geotechnical solution, but conventional binders have high environmental impact. This study investigates physico-chemical mechanisms governing mechanical behavior of self-compacting soil-cement materials produced with low-carbon binders, focusing on soil characteristics and clay mineralogy. The evolution of porosity and mechanical properties (compressive strength, elastic modulus, and Poisson’s ratio) was monitored during curing for five low-carbon binders combined with three natural soils of varying plasticity and mineralogy. To isolate mineralogical effects, synthetic soils containing controlled proportions of kaolinite, montmorillonite, feldspar, and quartz were also tested. Binder-soil interactions were characterised using X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR). Results show clay mineralogy strongly governs hydration and mechanical development. The spectroscopic observations suggest that montmorillonite-containing mixtures undergo less extensive binder reaction and that clay constituents may be altered under alkaline conditions. No single binder performs optimally across all soils, highlighting the need for soil-specific DSM binder design.