Evaluating fracture parameters of basalt fiber reinforced and pozzolana slurry modified recycled concrete produced from waste

Abstract

Recycling of construction and demolition waste provides one of the most effective paths for sustainable development, valorising recycled concrete, and environment protection. Unfortunately, due to substandard concrete matrix quality, lower strength and fracture parameters the practical applications of recycled concrete still remain the foremost concerns. To overcome these issues, a new effective strength enhancing approach was investigated in this study. More explicitly, two types of recycled concrete consisting of 20% and 100% of pozzolana slurry encrusted recycled aggregate and strengthened with various dosages of basalt fiber (BF) were evaluated in terms of fracture properties, namely compressive strength, fracture energy, fracture toughness, flexural strength, and elastic modulus. In addition, a digital image correlation (DIC) analysis was established to evaluate the strain contour variation while the microstructure study was conducted to inspect the concrete matrix quality. Experimental result revealed improvement in the ultimate load capacity as well as the overall load-CMOD response of BF modified formulations. For 20TRAC-1BF and 100TRAC-1BF, the fracture energy was improved by 91% and 56% and the fracture toughness was enhanced by 69% and 43%, respectively. Furthermore, the added dosages of BF were found useful in improving the flexural strength, elastic modulus, and toughness indices of both types of recycled concretes. From the DIC analysis, it was found that the BF modified concrete contained continuous spread of strain contours throughout the beam depth and revealed higher strain values than the reference sample. Lastly, the microstructure observation demonstrated better concrete matrix quality and BF-cement matrix interaction which thereby confirms the usefulness of the applied strength enhancing technique for the application of high strength fiber reinforced recycled concrete.