High volume waste foundry sand self-compacting concrete – Transitioning industrial symbiosis

Abstract

In light of massive industrialization, Industrial symbiosis has gained traction by most countries to employ wastes of one industry as a resource to another. Waste foundry sand obtained from the metal casting industry is a threat to the environment and the health of living beings due to the presence of organic and inorganic materials. However, this waste can be a resource for the construction industry. Despite its broad application scope, usage of waste foundry sand is highly limited due to inadequate understating of its performance in concrete. It becomes essential to understand the behaviour of waste foundry sand in concrete, more importantly, for accessing a strength-efficient and durable structure. The concrete samples were examined by conducting a number of experiments to investigate ties between strength, durability and microscopic insights. It has been observed that the inclusion of waste foundry sand can improve strength properties at later ages. Particular attention is paid to study the detailed microstructural investigations conducted on the concretes having up to 50% waste foundry sand. In addition, a leaching analysis was performed that revealed an increase in heavy metal concentration with the increasing WFS content. However, its concentration was below the acceptable limit, as evidenced by USEPA. Mineral and compositional characteristics monitored the effect of calcium aluminosilicate in the concrete matrix from early to later ages by X-ray diffraction and energy dispersive spectrometer analysis for the solid constituents of the concrete specimen, respectively. In light of the above, this study reveals that the strength properties of blended SCC were improving at later ages; significant improvement was discovered after 91 days of curing time. The compressive strength results were observed to increase by 16.6% for the specimens containing 40% waste foundry sand relative to control concrete at 91 days. The highest strength properties were achieved at 365 days, with 50% replacement ratios of waste foundry sand. The values for UPV were observed to improve as the curing age increases with the reduction in the rate of carbonation resistance of concrete. The carbonation depth was observed to be less than 1 mm for specimens containing 40% and 50% waste foundry sand for accelerated and atmospheric carbonation at 56 days and 2 years, respectively. The originality of the study relies on the possibility of developing waste foundry sand-self compacting concrete with the maximum utilization of waste foundry sand, achieving the targeted results. The study showed a good agreement between the waste foundry sand and concrete that creates a ground for the enhanced application of industrial symbiosis.