Bishir Kado

This study optimizes the durability performance of concrete by utilizing lateritic soil (LS) and calcium carbide waste (CCW) as partial replacements for fine aggregate and cement, respectively. A statistical method was employed to design the experiments and develop prediction models for key characteristics, including density, water absorption, and resistance to sulphuric acid attack (as measured by weight loss and compressive strength), using Response Surface Methodology (RSM). A central composite design (CCD) was employed to investigate the effects of CCW (0–20%) and lateritic soil (0–40%) on the properties of concrete. According to the results, higher CCW and laterite replacement levels reduce the durability of concrete by increasing its porosity and water absorption. Significant correlations were found in the responses that were successfully predicted by RSM-generated quadratic models. The ideal combination of 13.13% CCW and 18.7% LS was identified through multi-objective optimization, which maximized acid resistance while minimizing weight loss (8.84%) and water absorption (4.17%), resulting in an overall desirability of 75.4%. The experimental validation of this result revealed that the discrepancy between the predicted and experimental results was less than 5%. This indicates the potential of CCW-LS concrete for affordable, environmentally friendly construction in areas with limited resources.

This systematic review examines caught-in/between accidents in construction, revealing complex safety challenges involving machinery errors, vehicle incidents, loading mistakes, and structural collapses. The analysis highlights significant risks, including heavy equipment rollovers, trench cave-ins, and material shifts, with injuries ranging from minor to fatal. Despite the critical nature of these accidents, existing research demonstrates notable gaps, particularly in understanding long-term worker health impacts, economic consequences, and nuanced risk factors. Most studies insufficiently explore correlations between worker experience, age, and accident susceptibility, while gender-specific risks remain poorly documented. Training inadequacies and safety protocol non-adherence emerge as primary contributors to these incidents. This review identifies a pressing need for standardized, comprehensive safety interventions that address technological, human, and organizational factors. Recommendations include stricter safety regulations, enhanced training programs, advanced safety technologies, and robust support systems for workers. By fostering a holistic safety culture and addressing research gaps, the construction industry can potentially mitigate caught-in/between accidents, ultimately protecting worker well-being and improving overall productivity.

Standard fire test was carried out on 3 hollow steel tube and 6 foamed concrete filled steel tube columns. Temperature distribution on the columns was investigated. 1500 kg/m³ and 1800 kg/m³ foamed concrete density at 15%, 20% and 25% load level are the parameters considered. The columns investigated were 2400 mm long, 139.7 mm outer diameter and 6 mm steel tube thickness. The result shows that foamed concrete filled steel tube columns has the highest fire resistance of 43 minutes at 15% load level and low critical temperature of 671 ºC at 25% load level using 1500 kg/m³ foamed concrete density. Fire resistance of foamed concrete filled column increases with lower foamed concrete strength. Foamed concrete can be used to provide more fire resistance to hollow steel column or to replace normal weight concrete in concrete filled columns. Since filling hollow steel with foamed concrete produce column with high fire resistance than unfilled hollow steel column. Therefore normal weight concrete can be substituted with foamed concrete in concrete filled column, it will reduces the self-weight of the structure because of its light weight at the same time providing the desired fire resistance.