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Abstract

The rising concerns about the environment and sustainability are leading towards the need of recyclable materials to protect the environment and help in resource conservation. Sulfur concrete (SC) is a unique composite that does not utilize water and energy intensively produced cement. As a substitute to cement, molten sulfur firmly binds aggregates upon hardening. The sulfur concrete is recyclable and can be easily remolded in new applications. Moreover, sulfur is a by-product of the petroleum industry with almost zero carbon footprint. In this study, the mechanical (compressive strength and modulus of rupture) and durability properties (water absorption, salt attack-resistance, acid attack-resistance and alkali attack-resistance) of SC were evaluated after recasting without the addition of a new binder. The properties of fresh and recast SC were compared with those of the conventional Portland cement concrete (PCC) and sulfate resisting cement concrete (SRC). The results reveal that both the mechanical and durability properties of SC have significantly improved after the first recycling/recasting. However, there is a drastic decrease in strength and durability performance after the second recasting. Durability and mechanical performance of fresh and first recast SC is noticeably higher compared to PCC and SRC.

Introduction

The development of stringent environmental protection laws has increased the need to implement advanced methods for the consumption of sulfur from petroleum products. At the same time, the increasing demand for transportation and environmental regulations, consequently, has led to the production of large sulfur along with natural oil and gas [1]. According to the US Geological Survey [2], the worldwide production of sulfur is about 70 million metric ton. The chemical, physical and mechanical properties of sulfur offer potential for a wide range of its applications i.e. vulcanization of rubber, detergents, sulfuric acid, fertilizers, and construction. There is an increased focus on finding new applications to consume a large amount of sulfur waste in the construction industry.

The issues of global warming and sustainability are major concerns that have endangered the existence of life on earth. The main reason is the growth of industrial manufacturing and processing and one of such processes include cement concrete manufacturing. However, conventional cement concrete is not an environment friendly construction material [3]. It consumes large amounts of natural resources to meet its requirement of cement, coarse and fine aggregates. The most (about 82%) of the global warming emissions of concrete production comes from its main constituent cement [4]. Cement manufacturing burns high amounts of fuels to achieve the elevated temperature for the clinker production, also the calcination of limestone releases 40% of emissions of cement production. Cement industry also affects the nearby flora and fauna [5]. Dust from the cement industry can stunt the growth and productivity of plants and cash crops in the neighboring areas [6]. On the other hand, concrete wastes (both from construction and demolition practices) create social, environmental and waste management issues [7,8]. To save the environment and life, there is a grim need for sustainable, recyclable and eco-friendly composites to meet the demand for concrete in the construction industry.