Oyebisi Solomon, Shammas Mahaad Issa, Seyam Mohammed, Khuzwayo Bonga Praisegod
Civil Engineering and Geomatics Department, Durban University of Technology, Durban, South Africa.
Civil Engineering Department, The University of the South Pacific, Suva, Fiji.
Sci Rep. 2025 Jul 12;15(1):25265. doi: 10.1038/s41598-025-08745-1.
A properly optimized concrete mix design yields the required workability and strength for the fresh and hardened concrete to sustain desired loads and stresses over time, preventing premature failure. Thus, it is imperative to investigate the behavioural sensitivity of blended cement concrete to mix design variations. The research uses the Box-Behnken design of the response surface method to optimize the slump and compressive strength of blended cement concrete incorporating Shea nutshell ash (SNA). SNA was partially utilized as a Portland limestone cement (PLC) substitute at 5-15 wt% replacement levels using C25, C30, and C40 MPa mix design proportions and tested for compressive strength after 7-90 curing ages. Binder (SNA-to-PLC) ratio, water-to-binder ratio, binder-to-aggregate ratio, and curing age were engaged as continuous (independent) variables to optimize the response (dependent) variables (slump and compressive strength). The slump and compressive strength responses were optimized by the Box-Behnken design. The results exhibited a minimized slump and a maximized compressive strength with approximately 40-63% reduction and 10% increment. The correlations between the optimized and experimental variables were accurate and strong, with 98.89% and 98.44% R for slump and compressive strength. Ultimately, this response model is beneficial in determining the optimum mix design proportions to achieve the desired compressive strength of blended cement concrete incorporating repurposed waste materials.
一个经过适当优化的混凝土配合比设计能够为新拌混凝土和硬化混凝土提供所需的工作性和强度，使其能够长期承受预期的荷载和应力，防止过早失效。因此，研究混合水泥混凝土对配合比设计变化的行为敏感性至关重要。该研究采用响应面法的Box-Behnken设计来优化掺乳木果壳灰（SNA）的混合水泥混凝土的坍落度和抗压强度。使用C25、C30和C40 MPa的配合比设计比例，将SNA作为波特兰石灰石水泥（PLC）的部分替代品，替代量为5-15 wt%，并在养护7-90天后测试其抗压强度。将胶凝材料（SNA与PLC的比例）、水胶比、胶凝材料与骨料的比例以及养护龄期作为连续（独立）变量，以优化响应（依赖）变量（坍落度和抗压强度）。通过Box-Behnken设计优化坍落度和抗压强度响应。结果显示坍落度最小化，抗压强度最大化，坍落度降低约40-63%，抗压强度提高10%。优化变量与实验变量之间的相关性准确且强烈，坍落度和抗压强度的R分别为98.89%和98.44%。最终，该响应模型有助于确定最佳配合比设计比例，以实现掺有再生废料的混合水泥混凝土所需的抗压强度。
