Life cycle assessment of retaining wall backfilled with shredded tires

Purpose: This life cycle assessment (LCA) study compares energy consumption, greenhouse gas emissions, and environmental damages for two methods of constructing retaining structures, a traditional method involving a retaining wall backfilled with sand, and an alternative method involving a retaining wall backfilled with shredded tires. Methods: Taking into account the extraction and production of the used construction materials, loading, transport and installation, the cumulative energy demand (CED), global warming potential (GWP), acidification potential, Human Health Criteria Air-mobile, aquatic eutrophication potential, ozone depletion potential, and smog potential is determined for each construction method. The seven environmental impact categories are calculated using the software tool, ATHENA® Environmental Impact Estimator (ATHENA® EIE) for Buildings v5.2.0118. Results and discussion: The seven impact categories were reduced significantly by using shredded tires as retaining wall backfill; this is due to the decrease in the amounts of concrete, reinforcing steel, and fuel quantity consumed by building machines and vehicles transporting construction materials. Conclusions: The study concludes that in all examined impact categories alternative method provides a larger environmental benefit than the traditional method. Also, the results clearly demonstrate that the use of shredded tires is very effective as a sustainable alternative to retaining structures.For Sidi Bel Abbes University, this project has been realized within The Exceptional National Program (PNE 2016/2017) of the Algerian Ministry of Higher Education and Scientific Research. For Minho University, this work was supported by FCT - Fundação para a Ciência e a Tecnologia,” within ISISE, project UID/ECI/04029/2013 as well as by 318 COMPETE: POCI-01-0145-FEDER-007043

Life cycle assessment of concrete incorporating scrap tire rubber: Comparative study

At present, the environment suffers from two major problems, the first is the adverse effect of the production of the construction materials due to the resulting emissions and the second one is the increase of the consumption of the natural materials needed in the construction industry. There are interesting waste products such as the used tires that can be a resource of those materials to replace the natural resources in depletion. The use of scrap tire rubber to produce concrete in Algeria is not really an available technique. A life cycle assessment to compare an ordinary cement Portland concrete (Cref) and six rubberized concretes (CRm) and (CRg) from the environmental impact was carried out using ATHENA Estimator. The nine studied  environmental impact categories are Climate change, Acidification potential, particulate matters, Eutrophication, Destruction of the stratospheric ozone layer, Photochemical ozone creation, Primary energy consumption, Consumption of fossil fuels, and Cumulative energy demand. The results inter-compared show that the energy demand and the generated emissions in the case of ordinary concrete are superiors than those of the rubberized concretes; concretes made with natural aggregates and 5, 7.5 and 10% of crumb rubber and coarse rubber aggregates (CRm) are more environmentally friendly than (CRg) mixtures made with natural aggregates and 5, 7.5 and 10% of coarse rubber aggregates. It is also concluded that the environmental impacts depend on the amount of substituted aggregates

2D numerical analysis of a cantilever retaining wall backfilled with sand-tire chips mixtures

Previous research has shown that the backfill behind a retaining wall can be constructed with sand-tire chips (STC) mixture; this can lead to reduced horizontal displacements and earth pressures on the structure and allows lower design requirements, which implies lesser dimensions of the retaining wall. In this paper, the performance and stability of a cantilever retaining wall (CRW) with different STC mixtures, as lightweight backfill materials, were evaluated and analyzed numerically using the finite element software, RS2. The elastic parameters of the STC mixtures were computed using homogenization techniques, and the other engineering properties were obtained based on published literature. The results show that total displacement, vertical displacement, lateral pressures, lateral displacements, maximum shear forces and maximum bending moments are reduced considerably, and global stability of the retaining wall is enhanced when STC mixtures are used instead of sand alone. The mixture with the best overall mechanical behaviour was the one with a tire chips/sand ratio of 66.54/33.46 by weight or 81/19 by volume is used compared to the other mixing ratios