This study investigates the potential of graphene-based additives to improve the mechanical properties of compacted soil mixtures in rammed-earth construction, contributing to the development of environmentally friendly building materials. Two distinct soils were selected, combined with sand at optimized ratios, and treated with varying concentrations of a graphene liquid solution and a graphene-based paste (0.001, 0.005, 0.01, 0.05, and 0.1 wt.% relative to the soil-sand proportion). The effects of these additives were analyzed using the modified Proctor compaction and unconfined compressive strength (UCS) tests, focusing on parameters such as optimum water content (OWC), maximum dry density (MDD), maximum strength (qu), and stiffness modulus (E). The results demonstrated that graphene's influence on compaction behavior and mechanical performance depends strongly on the soil composition, with minimal variation between additive types. In finer soil mixtures, graphene disrupted particle packing, increased water demand, and reduced strength. In silt-sandy mixtures, graphene's hydrophobicity and limited interaction with fines decreased water absorption and preserved density but likewise led to diminished strength. Conclusions from the experiments suggest a possible interaction between graphene, soil's finer fraction, and potentially the swelling and non-swelling clay minerals, providing insights into the complex interplay between soil properties.

Salinity and sodicity greatly influences ongoing physical processes in soils. Organic matter may rehabilitate physical and mechanical properties of soils. Vermicompost as an amendment influences moisture-related parameters including consistency (plastic - PL and liquid limit - LL) and compaction. This study was conducted on soils (sandy-clay-loam) treated with different salinity levels (0.58 (control - irrigation water quality, tap water), 4 and 8 dS m(-1)) to investigate the effects of different vermicompost doses (0% (control), 2.5% and 5% w/w) on soil consistency limits and compaction. The pot experiment was carried out in a total of 27 pots, i.e. 3 (vermicompost doses) x 3 (salinity levels) x 3 (number of replicates). For Proctor compaction properties, maximum dry bulk density (MDD) reduced and optimum water contents (OWC) increased with increasing vermicompost doses under different salinity levels (p < .01). Increasing vermicompost doses under the lowest salinity level (0.58 dS m(-1)) yielded increasing optimum water contents for control (LL = 35.93% and PL = 25.85%). Optimum water contents were determined as 42.19% (LL) and 29.93% (PL) for 2.5% vermicompost dose and as 47.33% (LL) and 36.01% (PL) for 5% vermicompost dose under the lowest salinity level. LL, PL, OWC and MDD were significantly affected by vermicompost x salinity interactions. The highest maximum dry bulk density (1.92 g cm(3)) and the lowest optimum water contents (13.50%) were obtained from 0% vermicompost under the 8 dS m(-1) NaCl level. Mean weight diameter (MWD) values ranged from 0.690 mm for 0% VC treatment under high Na salt level (8 dS m(-1) NaCl) to 0.821 mm for 5% VC treatment under lowest Na salt level (0.58 dS m(-1) NaCl). The correlations between aggregate stability (particle size group 1-2 mm) and optimum water content were 0.647*, 0.587* and 0.598* as compared to correlations of -0.512*, -0.470*, and -0.617** between aggregate stability (particle size group 1-2 mm) and maximum dry bulk density for the 0, 4 and 8 dS m(-1) NaCl levels, respectively. MWD was positively correlated with OWC (0.386*) and negatively correlated with MDD (-0.385*). The greatest (2.39%) and the lowest (0.32%) soil organic matter values were respectively observed in 5% VC under the lowest salinity level (0.58 dS m(-1)) and 0% VC with at high Na salt level (8 dS m(-1) NaCl). It was concluded that vermicompost reduced compaction-induced damage in soils.