Ecological concrete blocks with sawdust additions: Overview of mechanical and microstructural analysis

Abstract

Environmental pollution is closely linked to construction practices, especially due to the reliance on non-sustainable materials. This study addresses the scientific challenge of optimizing the sustainability of non-structural concrete blocks through the addition of sawdust, added as a weight-based replacement for sand. The objective was to develop eco-friendly concrete blocks with sawdust to determine their physical, mechanical, and microstructural characteristics. A control sample was prepared, together with four treatments containing sawdust at 5%, 10%, 15% and 20% as a replacement for sand. Tests were conducted to evaluate compressive strength (CR) of individual masonry units, compressive strength of masonry piles, and diagonal shear strength of masonry walls. The results showed that increasing sawdust content led to higher water absorption compared to the control sample. The optimum performance was observed at a 5% sawdust addition, where the compressive strength of piles and the diagonal shear strength of walls increased by 8.59% and 5.51%, respectively. However, compressive strength in masonry units decreased as the sawdust percentage increased. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses revealed the presence of crystals such as quartz, calcite, albite, nahcolite, ettringite, cronstedtite, and an amorphous phase, along with chemical elements like carbon, oxygen, silica, and calcium, as well as a slight reduction in voids. The scientific novelty of this study lies in the integration of sawdust as a sustainable additive to improve specific mechanical properties while reducing environmental impact. It is concluded that it is feasible to produce eco-friendly concrete blocks with low sawdust doses that meet the required mechanical standards and exhibit suitable microstructural characteristics. These blocks can be effectively used in non-load-bearing walls and other construction applications where sustainability is a priority.