Influence of moulding speed on the consistency and mechanical performance of innovative soil blocks

Abstract

This study investigates the effect of moulding speed on the consistency and quality of innovative soil blocks used in low-cost housing construction. Specifically, it evaluates whether variations in pressure application speed during block production influence the mechanical properties of the resulting blocks and assesses the need for standardized moulding procedures in sustainable construction practices. Two moulding speeds, 30 mm/min and 45 mm/min, were applied during the production of compressed soil blocks. The suitability of the soil was first assessed through particle size distribution, Atterberg limits, and density tests. The produced specimens were subsequently tested to determine their compressive and tensile strengths. The mechanical performance of blocks manufactured at the two moulding speeds was compared to evaluate the influence of moulding speed on block quality and consistency. The soil used in this study was a lateritic soil classified as CL-ML (silty clay), under the Unified Soil Classification System (USCS). The particle size distribution analysis showed that the soil contained 8% clay, which is within the recommended range for soil block production. The plasticity index and liquid limit were 14.22% and 32.9%, respectively, satisfying the recommended requirements for earth construction materials. The soil density was 1.8 Mg/m³, which falls within the recommended dry density range of 1.75–2.25 Mg/m³ for compressed earth blocks. The average compressive strengths obtained were 0.74 and 1.04 MPa for blocks produced at moulding speeds of 30 mm/min and 45 mm/min, respectively. Similarly, the tensile strength results indicated superior performance at the lower moulding speed with 0.498 and 0.302 MPa, respectively. However, statistical analysis showed that the observed differences in strength were not significant. The findings indicate that moulding speeds may improve the compressive and tensile strength of soil blocks by enhancing compaction efficiency during production. Although the lower moulding speed improves the tensile strength of the blocks, the differences between the two moulding speeds were not statistically significant. Therefore, it is not necessary to control the compaction rate when making the soil blocks. The study demonstrates that the tested soil is suitable for compressed earth block production and provides evidence that can contribute to the development of standardized production guidelines for innovative soil blocks used in sustainable housing.