Mix design of eco-efficient high-strength mortars optimized by the compressible packing model

Dosagem de argamassas de alta resistência ecoeficientes otimizadas pelo modelo de empacotamento compressível

Abstract

The production of eco-efficient cement-based materials is essential to reduce CO₂ emissions from the construction industry. A substantial reduction in global CO₂ emissions can be achieved by using clinker in mortar and concrete more efficiently and using low-CO₂ minerals as partial replacements for Portland cement. However, the proportioning of eco-efficient composites is complex and the reduction in clinker content may affect its properties. This paper aims to optimize the mix design of high-strength mortars containing supplementary cementitious materials (limestone filler, fly ash, metakaolin, silica fume). The compressible packing model associated with a simplex mixture design were used together with chemical parameters, to limit the amount of active SCMs for the model iterations. The results show a significant decrease in the environmental impact of the mortars, which presented compressive strengths between 76 and 118 MPa at 91 days and binder indexes between 10 and 15 kg/m³/MPa. The reactivity of the SCMs (based on the modified Chapelle test) were successfully used to establish the Portland cement substitution (up to 13%), preventing the presence of unreacted SCMs and optimizing the use of limestone filler and sand, which have a lower environmental impact. The high-performance blends reached 8.73 kg CO₂e/MPa, up to a 30% reduction in CO₂e emissions compared to the mortar with only Portland cement.

Keywords:
carbon emission; supplementary cementitious materials; particle packing; eco-efficiency; simplex