Eco-efficient concrete, optimized by Alfred’s particle packing model, with partial replacement of Portland cement by stone powder

Concreto ecoeficiente, otimizado pelo modelo de empacotamento de Alfred, com substituição parcial do cimento Portland por pó de pedra

Abstract

The partial replacement of clinker by complementary cementitious materials can significantly contribute to the reduction of carbon emissions in the production of concrete. Another alternative to reduce these emissions is to increase the efficiency of the concrete, achieving higher compressive strength with lower consumption of cement. Particle packing models are efficient tools to optimize the composition of the matrix and contribute to the production of more eco-efficient concretes. In this context, the objective of the present study is evaluating the production of concretes with partial replacement of cement by stone powder, optimized by Alfred’s particle packing model, seeking to reduce cement consumption and CO₂ emissions per MPa of compressive strength. The replacement content of cement by stone powder was 20% by mass (equivalent to 22.4% by volume). Concretes were produced with different distribution factor (q) - 0.37; 0.21; 0.45 - to verify the influence of fines on the flow between particles and on the efficiency of the produced concrete. The analyses were carried out in terms of properties in the fresh state, hardened state, and sustainability parameters (cement consumptions and CO₂ emissions). The application of the proposed method resulted in a higher compressive strength than the expected for the water/cement ratio used (0.5). The most efficient concrete reached the compressive strength of 68 MPa with 240 kg/m³ of cement, which represents 3.5 kg of cement/m³/MPa and 3.1 kg of CO₂/m³/MPa, a value below the references found in the literature for conventional concretes. Therefore, the proposed method allows to produce more eco-efficient concrete, contributing to the use of waste and reducing CO₂ emissions.

Keywords:
particle packing; Alfred model; stone powder; eco-efficient concrete