NOPR Collection:

Fly ash cenospheres as reinforcement in different polymer composites – a comparative study of physical and mechanical properties

2015-06-01T00:00:00Z

Title: Fly ash cenospheres as reinforcement in different polymer composites – a comparative study of physical and mechanical properties Authors: Sampathkumaran, P; Kishore; Seetharamu, S; Pattanashetti, V V; Kumar, M Shekhar; Niranjan, H B Abstract: The work reports the preparation of fly ash cenospheres bearing polymer composites, using various polymer matrix materials namely, low density polyethylene, high density polyethylene, polystyrene and polymethylmethacrylate followed by evaluation of properties. The composites are synthesized by including about 18% by weight fly ash cenospheres, into various polymer matrices using brabender facility in the temperature range 120-160°C and at a mixing pressure of 50 MPa. Subsequently, they are cast into sheets through compression moulding. The test samples, made from the sheets, are characterized for physical as well as mechanical properties such as density, hardness, compression strength, impact response, wear and friction. The investigation reveals that the addition of fly ash cenospheres to various polymer matrices results in reduction of density. Further, improvements in the slide wear resistance and decrease in the co-efficient of friction values are noticed. As for interpreting the slide wear data, recourse to examination under scanning electron microscope is made in this paper. As regards the mechanical properties, hardness increases while the compression strength and impact energy decreases with inclusion of cenospheres in all the four types of samples investigated. Page(s): 354-362

Structural performance of a full-scale reinforced concrete frame strengthened by a steel grid shear wall

2015-06-01T00:00:00Z

Title: Structural performance of a full-scale reinforced concrete frame strengthened by a steel grid shear wall Authors: Kim, Heecheul; Park, Jung Woo; Park, Jin Young; Lee, Young Hak; Kim, Dae-Jin Abstract: This study proposes a steel grid shear wall that can provide a sufficient lateral resistance and can be used as a seismic retrofit solution for existing buildings. An experiment is performed on reinforced concrete (RC) frames with and without the steel grid shear wall. These frame specimens are subjected to combined axial and cyclic lateral loads that are applied by using three actuators. The experimental results show that the RC frame specimen with the proposed shear wall can retain higher lateral strength and ductility than the one without the steel grid wall. Page(s): 345-353

Usage of steel slag in concrete as fine and/or coarse aggregate

2015-06-01T00:00:00Z

Title: Usage of steel slag in concrete as fine and/or coarse aggregate Authors: Sezer, Gözde İnan; Gülderen, Mert Abstract: In this study, the use of steel slag as fine and/or coarse aggregate in concrete is investigated. For this purpose, 12 different concrete mixtures with different water/cement ratios of 0.40, 0.55 and 0.70 which include steel slag aggregate as fine and/or coarse aggregate are prepared. Compressive strength, split tensile strength, flexural strength, freeze-thaw resistance and water penetration depth of concrete mixtures containing steel slag aggregate are examined in comparison with concrete mixtures prepared by using crushed limestone aggregate. Eventually, concrete mixtures containing coarse steel slag show better performance than concrete mixtures containing limestone aggregate. Concrete mixtures containing fine steel slag show worse performance in comparison with concrete mixtures containing limestone aggregate. Page(s): 339-344

Monotonic and low cycle fatigue behaviour of concrete beams strengthened with textile reinforced concrete U-wrap

2015-06-01T00:00:00Z

Title: Monotonic and low cycle fatigue behaviour of concrete beams strengthened with textile reinforced concrete U-wrap Authors: Gopinath, Smitha; Murthy, A Rama Chandra; Iyer, Nagesh R Abstract: This paper presents experimental details on the effectiveness of textile reinforced concrete (TRC) as a structural strengthening material under flexure and shear. Two types of specimens, namely, plain concrete beams and reinforced concrete beams are strengthened with U-wrap configutation of TRC. Two types of fabrics having different weight per unit area are used for the investigations. Strengthened plain concrete beams are tested under three-point bending to investigate the flexural load carrying capacity, mid-point deflection and failure pattern. Further, experimental investigations are carried out on shear deficient RC beam strengthened with TRC as U-wrap under monotonic and low cycle fatigue loading. It is observed that under monotonic loading, there is about 19% increase in ultimate load carrying capacity and 852% increase in energy absorption for strengthened beam compared with un-strengthened beam. When the strengthened beam is subjected to low cycle fatigue loading, there is 20% reduction in ultimate load carrying capacity. But the ultimate deflection and failure pattern is found to be similar in both the cases. Page(s): 331-338