Variations et corrélations des paramètres relatifs aux sols gonflants

International audienceLes corrélations semi-empiriques ou purement empiriques ont toujours fait partie significative de la mécanique des sols. On présente dans ce travail plusieurs corrélations entre paramètres géotechniques mesurés en laboratoire afin d'estimer la pression et l'amplitude de gonflement des argiles expansives. Des régressions de types linéaires simples et multiples sont établies. Les correspondances entre paramètres proposés sont en très bonne concordance avec la littérature

Using Artificial Neural Networks Approach to Estimate Compressive Strength for Rubberized Concrete

Artificial neural network (ANN) is a soft computing technique that has been used to predict with accuracy compressive strength known for its high variability of values. ANN is used to develop a model that can predict compressive strength of rubberized concrete where natural aggregate such as fine and coarse aggregate are replaced by crumb rubber and tire chips. The main idea in this study is to build a model using ANN with three parameters that are: water/cement ratio, Superplasticizer, granular squeleton. Furthermore, the data used in the model has been taken from various literatures and are arranged in a format of three input parameters: water/cement ratio, superplasticizer, granular squeleton that gathers fine aggregates, coarse aggregates, crumb rubber, tire chips and output parameter which is compressive strength. The performance of the model has been judged by using correlation coefficient, mean square error, mean absolute error and adopted as the comparative measures against the experimental results obtained from literature. The results indicate that artificial neural network has the ability to predict compressive strength of rubberized concrete with an acceptable degree of accuracy using new parameters

Durability Properties of Five Years Aged Lightweight Concretes Containing Rubber Aggregates

Scrap tyres are one of the most important wastes. They can be used in different ways because of their availability and their non-degradable nature. This paper aims to demonstrate their reuse through durability properties experimental assessment of lightweight concretes aged five years, incorporating rubber aggregates as partial replacement of 5%, 7.5% and 10% of coarse/fine and coarse aggregates. The effect of the rubber aggregates on the lightweight concretes durability has been analysed. Firstly, the water absorption was evaluated, and then the mass losses were measured through many tests: freeze-thaw, elevated temperature and attack by Na2SO4 and HCl solutions. Wetting-drying cycles were carried out in order to accelerate the aging of the studied lightweight concretes and to reduce the tests duration. It has been observed that the water absorption decreased with small rubber content. The mass losses of the mixes were almost depending on rubber aggregates content and size, and the exposures duration

Geotextile reinforced strip footing: numerical modeling and analysis

This paper aims to evaluate the impact of geotextile used on strip footing settlement and bearing capacity in sandy soil. Comparing reinforced and unreinforced soil foundations required numerical analysis. To determine their influence on the footing bearing capacity, the stiffness, number, and spacing of reinforcing layers were investigated parametrically using the validated numerical model. The failure stage in the sand was simulated using the Mohr-Coulomb criterion and a non-associated flow rule. The results showed that the geotextile could improve the footing’s bearing capacity and reduce settlement. Finally, a comparison between the previously published experimental findings and the numerical results of this study showed good agreement.(undefined

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