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CONTENTS
Volume 2, Number 1, March 2014
 

Abstract
This paper demonstrates an experimental study to evaluate the effects of environmental exposures on the bond between ribbed Glass Fiber Reinforced Polymer (GFRP) reinforcing bars and concrete. The equation recommended by ACI 440-1R-06, for the bond stress,was evaluated in this study. A total of 16 pullout samples, 12with GFRP bars and 4with steel bars, were exposed to two different harsh environments for different periods of time. The exposed harsh environments included direct sun exposure and cyclic splash zone sea water. The variation in the shear (bond) strengths before and after exposure was considered as a measure of the durability of the bond between GFRP bars and concrete.Experimental results showed there is no significant difference of the bond strength between 60 and 90 days of exposures.It also showed that the empirical equation of the bond stress calculated by ACI 440-IR-06 is very conservative.

Key Words
bond; GFRP; pullout; shear; exposure; sea water

Address
Adil Al-Tamimi, Farid H. Abed and Abdulla Al-Rahmani: Department of Civil Engineering, American University of Sharjah, P.O.Box 26666, Sharjah, UAE

Abstract
The principal objective of this study is to deepen the characterization studies already led on sand concretes in previous works. Indeed, it consists in studying the effect of the sand type on the main properties of sand concrete: fracture and mechanical properties. We particularly insist on the determination of the fracture characteristics of this material which apparently have not been studied. To carry out this study, four different types of sand have been used: dune sand (DS), river sand (RS), crushed sand (CS) and river-dune sand (RDS). These sands differ in mineralogical nature, grain shape, angularity, particle size, proportion of fine elements, etc. The obtained results show that the particle size distribution of sand has marked its influence in all the studied properties of sand concrete since the sand having the highest diameter and the best particle size distribution has given the best fracture and mechanical properties. The grain shape, the angularity and the nature of sand have also marked their influence: thanks to its angularity and its limestone nature, crushed sand yielded good results compared to river and dune sands which are characterized by rounded shape and siliceous nature. Finally, it should further be noted that the sand concrete presents values of fracture and mechanical properties slightly lower than those of ordinary concrete. Compared to mortar, although the mechanical strength is lower, the fracture parameters are almost comparable. In all cases, the sand grains are debonded from the paste cement during the fracture which means that the crack goes through the paste-aggregate interface.

Key Words
sand, sand concrete; fracture mechanic properties; compliance; energy release rate; J-integral

Address
Belkacem Belhadj, Madani Bederina, Khadra Benguettache: Structures Rehabilitation and Materials Laboratory, University of Laghouat, Algeria

Michele Queneudec: Research Unit EPROAD, UPJV, Amiens, France



Abstract
Increasing emphasis on energy conservation and environmental protection has led to the investigation of the alternatives to customary building materials. Some of the significant goals behind understaking such investigations are to reduce the greenhouse gasemissions and minimize the energy required formaterial production.The usage of concrete around the world is second only to water. Ordinary Portland Cement (OPC) is conventionally used as the primary binder to produce concrete. The cement production is a significant industrial activity in terms of its volume and contribution to greenhouse gas emission. Globally, the production of cement contributes at least 5 to 7 % of CO2. Another major problem of the environment is to dispose off the fly ash, a hazardous waste material, which is produced by thermal power plant by combustion of coal in power generation processes. The geopolymer concrete aims at utilizing the maximum amount of fly ash and reduce CO2 emission in atmosphere by avoiding use of cement to making concrete. This paper reports an experimental work conducted to investigate the effect of curing conditions on the compressive strength of geopolymer concrete prepared by using fly ash as base material and combination of sodium hydroxide and sodium silicate as alkaline activator.

Key Words
fly ash based geopolymer concrete, alkaline activator, ambient curing, hot curing, compressive strength

Address
Amol A. Patil, H.S.Chore and P.A.Dode: Department of Civil Engineering, Datta Meghe College of Engineering, Sector-3, Airoli, New Mumbai- 400708 (India)

Abstract
Corrosion in RCC structures is one of the most important factors that affects the structure‟s durability and subsequently causes reduction of serviceability. The most severe cause of this corrosion is chloride attack. Hence, to prevent this to happen proper understanding of the chloride penetration into concrete structures is necessary. In this study, first the mechanism of this chloride attack is understood and various parameters affecting the process are identified. Then an FEM modelling is carried out for the chloride diffusion process. The effects of fly ash and slag on the diffusion coefficient and chloride penetration depth in various mixes of concretes are also analyzed through integrating Virtual RCPT Lab and FEM.

Key Words
concrete; chloride diffusion; rapid chloride permeability test; FEM simulation

Address
Sajal K. Paul and Sudhirkumar V. Barai: Department of Civil Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721 302, India
Subrata Chaudhuri: UltraTech Cement Ltd., Aditya Birla Group, Mumbai 400 093, India

Abstract
This paper presents an analysis of the results of an experimental program on the performance of a novel configuration of a hybrid FRP-concrete beam. The beam section consists of a GFRP pultruded profile, a CFRP laminate, and a concrete block all wrapped up using filament winding. It was found that the thickness of the concrete block and the confinement by the filament-wound wrapping had a profound effect on the energy dissipation behaviour of the beam. Using a shear punching model, and comparing the predicted results with the experimental ones, it was found that beyond a given value of the concrete block thickness, the deformational behaviour of the beam shifts from brittle to ductile. It was also found that the filament-wound wrap had many benefits such as providing a composite action between the concrete block and the GFRP box, improving the stiffness of the beam, and most importantly, enhancing the load carrying ability through induced confinement of the concrete.

Key Words
high strength concrete;steel fibers;finite element analysis (FEA); hybrid beam, pultrusion; filament winding

Address
A. Chakrabortty and A. Khennane: School of Engineering and Information Technology, UNSW Canberra, Northcott Drive, Canberra , Australia


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