Suitability of using cemented gravel and clay blocks reinforced with steel fiber as compressed stabilized earth blocks

Compressed stabilized earth blocks (CSEBs) reinforced with steel fiber can be a suitable alternative construction material for retaining walls or hydraulic structures, which often face aggressive environmental conditions such as heavy rainfall, strong winds, and high erosion levels. This paper examines the suitability of cement-treated gravelly and clayey soils reinforced with steel fiber as CSEBs based on the requirements for various unfired earthen blocks. Cement contents of 5–7 % and fiber volume fractions of 0.6–1.2 % were utilized to create the CSEBs at the optimum moisture contents for both gravel and clay. Dry and wet compressive strength tests were performed to determine the mechanical characteristics, while wet-to-dry compressive strength ratio, water absorption, and erosion rate tests were conducted to examine the durability properties. Additionally, fiber pullout tests and SEM analyses were carried out to investigate the interface interaction between the soil-cement matrix and steel fiber. The results showed that the gravel blocks had higher strength than the clay blocks by 1.5–5.6 times and were more durable by about 1.5 times. The erosion rates significantly decreased with increasing fiber content for clay blocks due to the fiber’s capacity to hold the clay-cement matrix together. The interface bond strength between steel fiber and cemented clay was more than 1.74 times that between steel fiber and cemented gravel, as confirmed by SEM photos. A more compacted interface nature was observed in the cemented clay matrix compared to the cemented gravel. Therefore, the clay blocks reinforced with steel fiber exhibited higher bridging capability than the gravel blocks. The clay blocks demonstrated a ductile response, whereas the gravel blocks showed a semi-ductile response. Considering the improved toughness ratio of 2.0, the gravel block with 5 % cement and 1 % fiber and the clay block with 7 % cement and 1 % fiber were identified as the most suitable mix proportions based on eco-friendliness and economic sustainability.