Análise das propriedades de concreto com substituição parcial do cimento por biochar

Abstract

The construction industry is responsible for a significant portion of global CO2 emissions, primarily driven by Portland cement production and intensive natural resource extraction. In this context, biochar emerges as a promising alternative to mitigate these impacts, acting as a supplementary cementitious material and internal curing agent . This study aimed to analyze the influence of partial cement replacement by biochar on the properties of concrete in fresh and hardened states. The experimental program involved the production of a reference mix (REF) and mixes with 5% dry biochar substitution (Series S), as well as mixes with 2.5%, 5.0%, and 7.5% pre-soaked biochar (Series PU). Tests were performed for slump, axial compressive strength, splitting tensile strength, static modulus of elasticity, and capillary water absorption . The results demonstrated that dry biochar severely compromised workability, requiring an increase in the water/cement ratio, although it provided strength gains and reduced capillarity due to internal curing. The pre-soaking methodology proved effective in maintaining consistency and controlling the w/c ratio. The mix with 2.5% pre-soaked biochar (BC-2.5-PU) presented the best overall performance, surpassing the reference concrete in compressive strength (26.72 MPa) and tensile strength at 28 days, without impairing workability. However, higher contents (5.0% and 7.5%) in the pre-soaked series resulted in decreased strength, indicating that biochar acts as a less rigid inclusion in the matrix. It is concluded that the use of pre-soaked biochar at low dosages is technically and environmentally viable, contributing to concrete sustainability through internal curing and potential carbon sequestration. [resumo fornecido pelo autor]