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CONTENTS
Volume 6, Number 3, June 2018
 

Abstract
Utilization of mine waste rocks and tailings in concrete as aggregates will help in sustainable and greener development. The literature shows the potential use of iron ore tailings as a replacement of natural fine aggregates. As natural sand reserves are depleting day by day, there is a need for substitution for sand in concrete. A comprehensive overview of the published literature on the use of iron ore waste and tailings and other industrial waste in concrete is being presented. The effect of various properties such as workability, compressive strength, split tensile strength, flexural strength, durability and microstructure of concrete have been presented in this paper.

Key Words
concrete; iron ore waste and tailings; strength; durability

Address
B.C. Gayana and Karra Ram Chandar: Department of Mining Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore-575025, India

Abstract
The numerical investigations have been carried out on deep beam with opening subjected to static monotonic loading to demonstrate the accuracy and effectiveness of the finite element based numerical models. The simulations were carried out through finite element program ABAQUS/CAE and the results thus obtained were validated with the experiments available in literature. Six simply supported beams were modelled with two square openings of 200 and 250 mm sides considered as opening at centre, top and bottom of the beam. In order to define the material behaviour of concrete and reinforcing steel bar the Concrete Damaged Plasticity model and Johnson-Cook material parameters available in literature were employed. The numerical results were compared with the experiments in terms of ultimate failure load, displacement and von-Mises stresses. In addition to that, seventeen beams were simulated under static loading for studying the effect of opening location, size and shape of the opening and depth, span and shear span to depth ratio of the deep beam. In general, the numerical results accurately predicted the pattern of deformation and displacement and found in good agreement with the experiments. It was concluded that the structural response of deep beam was primarily dependent on the degree of interruption of the natural load path. An increase in opening size from 200 to 250 mm size resulted in an average shear strength reduction of 35%. The deep beams having circular openings undergo lesser deflection and thus they are preferable than square openings. An increase in depth from 500 mm to 550 mm resulted in 78% reduced deflection.

Key Words
deep beam; numerical studies; opening size; opening shape; opening location; span-depth ratio

Address
K. Senthil, A. Gupta and S.P. Singh: Department of Civil Engineering, National Institute of Technology Jalandhar, Jalandhar, Punjab 144011, India

Abstract
This study presents the effects of geometrical dimensions of concrete gravity dams on the seismic response considering different base width/dam height (L/H) ratios. In the study, a concrete gravity dam with the height of 200 m is selected and finite element models of the dam are constituted including five different L/H ratios such as 0.25, 0.5, 0.75, 1.00, 1.25. All dams are modeled in ANSYS software considering damreservoir-foundation interaction. 1989 Loma Prieta earthquake records are applied to models in upstreamdownstream direction and linear time history analyses are performed. Dynamic equilibrium equations of motions obtained from the finite element models of the coupled systems are solved by using Newmark time integration algorithm. The seismic response of the models is evaluated from analyses presenting natural frequencies, mode shapes, displacements and principal stresses. The results show that the L/H ratios considerably affect the seismic response of gravity dams. Also, the model where L/H ratio is 1.00 has more desirable results and most appropriate representation of the seismic response of gravity dams.

Key Words
base width-dam height ratio (L/H); finite element modeling; geometrical dimensions effect; gravity dams; seismic response

Address
Baris Sevim: Yildiz Technical University, Department of Civil Engineering, Esenler, Istanbul, Turkeyl Istanbul Gelisim University, Department of Civil Engineering, Avcilar, Istanbul, Turkey

Abstract
In the present paper, the results of an experimental study of the bond between repair materials and mortar substrate subjected to hot climate is presented. Half-prisms of size 40

Key Words
self compacting mortar; natural pozzolana; substrate; hot climate; bond

Address
A. Benyahia and M. Ghrici: Geomaterials Laboratory, Civil Engineering Department, Hassiba Benbouali University of Chlef, P.O. Box 151, Chlef 02000, Algeria

Abstract
The objective of this study was to evaluate the influence of silica fume (SF) on the hydration heat and compressive strength of concrete. Portland cement with w/(c+sf) ratios varying between 0.25 to 0.45 was substituted by 10%, 20% and 30% of SF by mass. A superplasticizer was used to maintain a fluid consistency of the concrete. The heat of hydration was monitored continuously by a semi-adiabatic calorimetric method for 10 days at 20oC. Compressive strengths are tested for each mixture until age of 180 days. The results show that silica fume considerably influences the evolution and the ultimate values of the compressive strengths as well as the hydration heat especially for 10% rate. The w/b ratio has a considerable effect where its decrease modifies compressive strength and hydration heat more than silica fume. The correlation of the obtained results allows deducing of ultimate properties as well as the ages to reach half of their values. The correlation coefficients are close to unity and reflect the judicious choice of these relationships to be used to predict compressive strength and hydration heat.

Key Words
cement; compressive strength; half age; hydration heat; relationship; silica fume; ultimate values

Address
Mahdjoub Djezzar, Karim Ezziane, Abdelkader Kadri: Laboratory Geomaterials, University Hassiba Benbouali of Chlef, 02000, Chlef, Algeria
El-Hadj Kadri: Laboratory L2MGC, University of Cergy Pontoise, F9500, Cergy Pontoise, France

Abstract
This paper presents an experimental investigation on the performance of concrete with and without glass powder (GP) subjected to elevated temperatures. Mechanical and physicochemical properties of concretes were studied at both ambient and high temperatures. One of the major environmental concerns is disposal or recycling of the waste materials. However, a high volume of the industrial production has generated a considerable amount of waste materials which have a number of adverse impacts on the environment. Further, use of glass or by-products in concrete production has advantages for improving some or all of the concrete properties. The economic incentives and environmental benefits in terms of reduced carbon footprint are also the reason for using wastes in concrete. The occurrence of spalling, compressive strength, mass loss, chemical composition, crystalline phase, and thermal analysis of CPG before and after exposure to various temperatures (20, 200, 400, and 600oC) were comprehensively investigated. The results indicated that, the critical temperature range of CPG was between 400oC and 600oC.

Key Words
powder glass; concrete; high temperature, spalling, mass loss

Address
Messaouda Belouadah, Zine El Abidine Rahmouni: Geomaterials Development Laboratory, Civil Engineering Department, Faculty of Technology, M\'sila University, M\'sila (28000), Algeria
Nadia Tebbal: Geomaterials Development Laboratory, Civil Engineering Department, Faculty of Technology, M\'sila University, M\'sila (28000), Algeria


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