EPS supported fibre reinforced concrete slabs on grade built over soft clay

Walid El Kamash, Hany El Naggar

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Earth Walls and Foundations

ABSTRACT: Soft clay soil may be considered as challenge against constructing many geotechnical applications. Constructing rigid slabs on soft clay leads to a concentration of stresses at edges which results in large settlements. In this study, EPS, extended poly-styrene geofoam was used to replace the soft soil in order to redistribute stresses beneath the slab and to control the settlement. A two-dimensional finite difference numerical method was adopted. This numerical method was first verified against experimental data and then used to conduct an extensive parametric study to explore the feasibility of using EPS beneath steel fibre reinforced concrete (SFRC) slabs on grade. The parametric study was extended to consider the change of the thickness of geofoam layer and different types of soft clay under different loading conditions. Discussion for the numerical results was performed and conclusions were drawn. . RÉSUMÉ Sol argileux souple peut être considéré comme un défi contre la construction de nombreuses applications géotechniques. Construire des dalles rigides sur argile molle conduit à une concentration de contraintes au niveau des bords qui se traduit par de grandes colonies. Dans cette étude, EPS, prolongée poly-styrène Geofoam a été utilisé pour remplacer le sol mou afin de répartir les contraintes sous la dalle et de contrôler le règlement. Procédé finis à deux dimensions différence numérique a été adoptée. Cette méthode numérique a été vérifié par rapport aux données expérimentales et ensuite utilisé pour réaliser une étude paramétrique vaste à explorer la possibilité d'utiliser EPS sous la fibre d'acier renforcé (SFRC) dalles de béton sur terre. L'étude paramétrique a été étendu pour examiner le changement de l'épaisseur de la couche de Geofoam et différents types d'argile molle sous différentes conditions de chargement. Discussion des résultats numériques a été effectuée et les conclusions. 1 INTRODUCTION There is a continuous need for constructing slabs on grade. Slab on grade is a relatively flat concrete structure built on top of the soil at ground level. This kind of slabs is used in roads, parking areas, airport runways, and in industrial facilities and in oil and gas plants under forklift tracks. Steel fibre reinforced concrete (SFRC) is a concrete that contains fine or coarse aggregates along with discontinuous steel fibres. The main purpose of using steel fibres is to provide the concrete with some post-cracking strength capacity and flexural toughness. In addition, the steel fibres give more ductility, impact resistance, fatigue endurance, crack width control, and durability [ACI 544 2009]. Construction over soft soils presents technical challenges. For example, construction of slabs on soft clay leads to a concentration of stresses at edges which results in large settlements. Accordingly, there is a need for developing methods to control settlements. Expanded Polystyrene (EPS) Geofoam is widely used as construction material in the field of geotechnical engineering, due to its successful variety of applications such as compressible inclusion in retaining walls and in embankments. Also, EPS as a lightweight material was used as replacement material for soft soil beneath raft foundations in order to decrease the overall settlement. Several researchers investigated various material properties of EPS. For example, Padade and Mandal (2012) performed a series of triaxial tests on EPS Geofoam specimens to characterize its strength parameters. They determined strength parameters for different densities of EPS Geofoam. Awol (2012) examined the creep behaviour of EPS geofoam in a parametric study using different sample sizes. In this paper, EPS geofoam was used to replace the soft soil in order to redistribute stresses beneath the slab and to control the settlement for slabs on grade built on soft clays. A mathematical model using Finite Difference method was used to analyze rigid slabs under different types of loads. 2 VERIFICATION OF NUMERICAL MODEL To ensure the reasonableness of the numerical model to be used for the parametric study, an experimental case study as described below was selected for the verification. The details of this experimental case study can be found in the literature (Abdelrahman and Elragi, 2006). The numerical verification based on a mechanical analysis

RÉSUMÉ: upported fibre reinforced concrete slabs on

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Cite this article:
Walid El Kamash; Hany El Naggar (2014) EPS supported fibre reinforced concrete slabs on grade built over soft clay in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper159,author = Walid El Kamash; Hany El Naggar,title = EPS supported fibre reinforced concrete slabs on grade built over soft clay,year = 2014}