International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
INVESTIGATION ON FLEXURAL STRENGTH OF HIGH STRENGTH SILICA FUME CONCRETE Pranab Chakraborty1 1.M.Tech Scholar, Department of Civil Engineering, Narula Institute of Technology, Kolkata, India ---------------------------------------------------------------------***--------------------------------------------------------------------particles with an average particle diameter of 150 nm. Abstract - Concrete as we know is relatively strong in compression and weak in tension. In reinforced concrete The main field of application is as pozzolanic material members, little dependence is placed on the tensile strength of for high performance concrete. In cementations concrete since steel reinforcing bars are provided in all tensile compounds, silica fume works on two levels, the first forces. however, tensile stresses are likely to develop in concrete one described here is a chemical reaction called the due to drying shrinkage, rusting of steel reinforcement, “pozzolanic” reaction. The hydration (mixing with temperature gradients and many other reasons. The deflection water) of Portland cement produces many compounds, and cracking behavior of concrete structure depend on flexural properties of concrete. Therefore, the knowledge of flexural including calcium silicate hydrates (CSH)and calcium strength of concrete is of importance. hydroxide (CH). The CSH gel is known to be the source In the present work a detailed experimental study on the of strength in concrete. When silica fume is added to mechanical properties i.e. the flexural strength of high-strength fresh concrete it chemically reacts with the CH to concrete of grades M40 at 7 days and 28 days characteristic produces additional CSH. The benefit of this reaction is strength with different replacement levels viz., 3%, 6%, 9%, 12% to increased strength and chemical resistance. The bond and 15% of cement with silica fume are considered. Standard between the concrete paste and the coarse aggregate, in prisms(100mmX100mmX500mm) were considered in the investigation. The investigations revealed that the use of waste the crucial interfacial zone, is greatly increased material like silica fume improved the flexural strength resulting in compressive strengths that can exceed characteristics of high strength concrete at the age of 28-days & 15,000 psi. The additional CSH produced by silica fume reached a maximum value of 12% is more resistant to attack from aggressive chemicals replacement level for M40 concrete which is otherwise then the weaker CH. Thus it is one of the world’s most hazardous to the environment. valuable and versatile admixtures for concrete and cementitious products. Flexural strength, a mechanical parameter is defined Key Words: High Performance; Workability; Silica Fume; as ability to resist deformation under load. The Flexural strength Characteristics and partial deflection and cracking behavior of concrete structure replacement. depend on these properties of concrete. Due to many reasons such as temperature gradients, drying shrinkage, rusting of steel reinforcement stresses developed. A concrete road is called upon to resist tensile stresses from two principal sources-wheel load s 1.INTRODUCTION and volume changes in the concrete. Wheel loads may High-strength and High-performance concrete are cause high tensile stresses due to bending, when there being widely used throughout the world and to produce is an inadequate sub grade support. Volume changes, them it is necessary to reduce the water/cement ratio resulting from changes in temperature and moisture, and increase the cement content. Engineers are may produce tensile stresses, due to warping and due to continually pushing the limits to improve its the movement of the slab along the subgrade. Stresses performance with the help of innovative chemical due to volume changes alone may be high. The admixtures and supplementary cementitious materials longitudinal tensile stresses in the bottom of the because production of cement involves emission of pavement caused by restraint and temperature large amounts of carbon-dioxide gas into the warping, frequently amounts to as much as 2.5 MPa at atmosphere, a major contributor for greenhouse effect certain periods of the year and the corresponding stress and the global warming. Silica fume is an ultrafine in the transverse direction is approx.0.9 MPa. These powder collected as a by-product of the silicon and stress are additive to those produced by wheel loads on ferrosilicon alloy production and consists of spherical © 2017, IRJET
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