Self-compacting concrete with low cement consumption: impact of the reduction of cement consumption on the compressive strength

ABSTRACT The consolidation of concrete as the second most consumed material in the world has instigated the search for solutions to reduce clinker consumption and CO2 emissions. Aiming to provide a contribution to environmental sustainability and the cement industry, this research seeks to analyze the economic viability of self-compacting concrete (SCC) with low cement consumption. A study of the optimization of the granular skeleton and the composition of the paste was carried out using the Gomes (2002) dosing method for the SCC. Reductions of up to 25% of the cement consumption were measured in relation to the reference SCC. Regarding the relative cement consumption and unit cost indexes per MPa developed in 1 m3 of concrete, it was verified that the SCC’s with low cement consumption showed reductions of up to 34.75% and 16.83%, respectively, while being compared to the reference SCC. The greater effectiveness in the reduction of the consumption relative to the mechanical resistance to compression than in the consumption of cement per cubic meter of concrete observed, is due to the observation of higher levels of mechanical resistance to compression for the composition with lower paste volume and higher proximity to the optimal void index found in the aggregate packaging stage. This result shows that even in the lower dosage circumstances, the mechanical compressive strength can be increased, thus demonstrating the technical and financial superiority of the SCC with low cement consumption compared to conventional SCC dosages, in addition to the sustainability gains obtained by the reduction of the clinker consumption and the CO2 emissions inherent to the lower amount of cement mass per cubic meter of concrete.

摘要 混凝土作为全球第二大消耗材料的普及态势，催生了针对减少熟料消耗与二氧化碳排放的解决方案探索。为助力环境可持续发展与水泥行业发展，本研究旨在分析低水泥用量自密实混凝土（self-compacting concrete，SCC）的经济可行性。本研究采用Gomes（2002）配料法对SCC的骨料级配骨架与浆体组成开展优化研究。相较于基准SCC，该研究中水泥用量最高可降低25%。针对每立方米混凝土的相对水泥用量与单位抗压强度（每兆帕）成本两项指标，经验证，低水泥用量SCC相较于基准SCC，分别可实现最高34.75%与16.83%的降幅。相较于每立方米混凝土的水泥用量降幅，本次研究观察到的抗压强度相对降幅更为显著，其原因在于：当浆体体积更低且骨料充填阶段的空隙率更接近最优值时，对应配合比的抗压强度更高。该研究结果表明，即便在更低的配合比设计条件下，仍可提升混凝土抗压强度，由此证明低水泥用量SCC相较于传统配合比SCC，兼具技术与经济优势；同时，每立方米混凝土的水泥用量降低可减少熟料消耗与伴随产生的二氧化碳排放，进而带来环境可持续效益。