International Concrete Abstracts Portal

The main objective this study was to investigate the effect of waste steel fibers on the mechanical properties of concrete. The steel fibers obtained from waste tires were used, and physical and mechanical properties of these fibers were determined as a first step of the study. Fibers having different aspect ratios were used in concretes at various amounts. A concrete without any fibers was also cast. Compressive, flexural and splitting tensile strengths of the concretes were obtained. Fracture energies were also obtained using a closed-loop testing machine. Results showed that post-cracking strength and toughness of the concretes containing waste steel fibers were significantly increased. Flexural and splitting strength of the concretes were also improved. The experimental results showed that the waste steel fibers recovered from waste tires could be used for the production of steel fiber reinforced concretes. Utilization of waste steel fibers can help to protect environment by reducing the need for steel fiber production. Thus, the reuse of waste fibers in concrete contributes to a more sustainable fiber reinforced concrete production. Since the costs of the waste steel fibers are substantially lower than the commercial steel fibers, more economical steel fiber reinforced concretes can also be obtained.

Concrete is the most versatile construction material. However, the image of concrete looks often one of something non-friendly from an environmental point of view. Further developments, “green chemistry” and new techniques, should continue to be introduced into the cement and concrete industry. This will provide distinct alternatives to OPC dominating inside cement market. Simultaneously new scientific and technological breakthroughs are required. One of such additional strategies is based on advanced concrete technology concepts, which enables the reduction of the quantity of cement used in concrete, by combining fillers and various admixtures. Another strategy is based on a new design of the structural component, to evaluate the use of different materials and to achieve an overall reduction of the environmental impacts. This strategy highlights Life Cycle Analysis and Design, Performance Standards for Durability, Environmentally Driven Design and the role of the reinforcement, because the conventional steel reinforcement contributes to environmental footprint as much as the cement in the concrete. Composite materials, including polymer composite reinforcement, non-metallic fibers and the external reinforcement for repair and strengthening, would be widely used in modern construction. Additional benefits of synergy between these different solutions might be realized leading to reduction of more than 50% of environmental load.

Estimation of energy and material input-output during the production and other lifecycle stages is the most basic and repeated procedure to evaluate the environmental impact. Therefore, it is important to develop an accurate, convincing and field-verified model for estimating the material and energy input-output at each lifecycle stages and at each plant or site. With this background, we have been developing energy-use estimation model at concrete production stage. In this paper, we firstly present the unique characteristics of concrete production process in Japan based on our previously proposed model. With this model, we statistically estimate three factors through the field questionnaire survey on ready-mixed concrete plants. The estimation has shown the following characteristics in electric consumption; 1) major manufacturing machineries such as mixer, belt conveyer and blowers are less electric consuming than facilities in constant operation (ex. air compressor), 2) around half of the constant electric consuming facilities can be stopped (at least in some conditions) when concrete shipping is not in queue, which may imply possible options for the reduction of electric energy-use.

The construction industry is accountable for about 50 percent of the global resource consumption. Within this, traditional concrete is one of the products with a manufacturing process that has a relatively large impact on the environment. As a result of the rising awareness regarding sustainability, concrete suppliers, product manufacturers, and building contractors are concerned about which environmental impact their product has. Based on a life cycle assessment (LCA) it is possible to analyze the different stages in the life cycle of structures and to evaluate the respective impacts. Such a study is presented here for a producer of high-strength concrete building materials, applying a cradle-to-gate approach with options. Specific company data were combined with general input from databases, and a functional unit of 1m^³ was adopted to be able to compare the different results. Based on this, it was determined that whereas the reinforcing and prestressing steel and the cement dominate the impact contributions, other factors such as transport by road, maintenance, aggregates, fabrication and concrete waste production during fabrication are non-negligible. A further impact study shows that several adaptions can potentially reduce the impact on the environment with 20 to 30 percent, depending on the assessment method used.

the main aim of the paper is to evaluate performances of tile adhesive mortars produced with recycled glass powder as partial replacement of natural sand and calcium carbonate filler. An experimental activity was carried out in order to use glassy waste in production of pre-packed mortars for tile installation having performances comparable to those of products currently available on the market in order to reduce both the consumption of virgin raw materials (sand and limestone filler) in the industrial process and the amount of waste to landfill. Glassy waste coming from recycling of glass packaging seems to be particularly indicated to manufacture cementitious mixtures since it can act as pozzolanic material improving both rheological and physical properties of proprietary mortars for repair of reinforced concrete structures, protective and decorative coatings for walls and adhesives for ceramic tile and natural stone installation. Re-use of glassy waste, finally, has beneficial effects in terms of both cost reduction and environmental impact.