This paper presents an experimental investigation to study the effect of openings on the strength and behaviour of reinforced concrete (RC) frames infilled with precast fibre reinforced concrete panels. One bay-three storey, 1/4th scaled down model frame specimens were constructed and tested under reversed cyclic lateral loading. The parameter investigated was the shape of the opening. The precast panelled frames were also compared with the traditional brick masonry infilled frames. The test results indicated that the strength, stiffness and energy dissipation capacity of fibre reinforced concrete infilled frames considerably improved when compared with bare frame and brick masonry infilled frames.The test results also indicated that fibre reinforced concrete infills with openings significantly improved the performance of RC frames when compared with the brick masonry infills.
This paper aims at investigating the shear strength and joint distortion of beam column joints made using Steel Fibre Reinforced Self Compacting Rubberized Concrete (SFRSCRC) with and without steel fibres and compare with the conventional Self Compacting Concrete (SCC) joints. The behaviour of the beam column joints under monotonic, repeated and reverse cyclic loads has been investigated. The results indicate that the Self Compacting Rubberized Concrete (SCRC) and Steel Fibre Reinforced Self Compacting Rubberized Concrete (SFRSCRC) specimens could bring about improvements in the behaviour of beam column joint under cyclic loads, especially in terms of the ductility of the specimens. The use of SFRSCRC contributes to reduction in the joint distortions, irrespective of the loading condition, owing to the elastic nature of the rubber particles.
The addition of small closely spaced and uniformly dispersed fibres to concrete would act as crack resistor and would substantially improve its properties. The addition of more than one type of fibre in concrete is known as Hybrid Fibre Reinforced Concrete. Combining fibres with different geometry and mechanical properties can improve the mechanical properties of fibre reinforced concrete. These composites take advantage of different and synergistic effects on mechanical properties of each fibre type. Macrofibres of steel, due to their high modulus and improved bonding characteristics are known to improve toughness of concrete at relatively small crack openings; on the other hand, micro-fibres of polypropylene are expected to mitigate shrinkage cracking, improve the tensile strength of the matrix, improve the crack growth resistance and enhance strain capability. However there is a weak zone between fibres and paste in fibre reinforced concretes and this weak zone is full of porosity, especially in hybrid fibre reinforced concretes. Therefore, using of pozzolanic materials is required to reduce the porosity.
In this paper shrinkage characteristics of metakaoline based hybrid fibre reinforced concrete is studied. Main aim of this experimentation is to determine the shrinkage characteristics of metakaoline based hybrid fibre reinforced concrete, in which 20 % of cement is replaced by metakaoline. Different fibres used in this experimentation are steel fibres (SF), galvanized iron fibres (GIF), waste coiled steel fibres (WCSF), high density polyethylene fibres (HDPEF), waste plastic fibres (NPF) and polypropylene fibres (PPF). Different combinations of hybrid fibres used in this experimentation are (SF+GIF), (SF+WCSF), (SF+HDPEF), (SF+WPF) and (SF+PPF).
Concrete is subjected to changes in volume either autogenous or induced. This volume change is called as Shrinkage. It is one of the most detrimental properties of concrete that affects the long-term strength and durability. Practically, the aspect of volume change in concrete is important from the point of view that it causes unsightly cracks in concrete. An investigation is carried out on M25 grade fibres reinforced concrete to study the effect of strength and shrinkage with inclusion of fly ash and bottom ash with and without fibres. Fly ash is used as a replacement of cement at 0%, 10%, 20%, 30%, 40% and 50%, bottom ash is used as a replacement of fine aggregates at 0%, 10%, 20%, 30%, 40% and 50% with 0.5% of carbon fibres by volume of concrete. In this study following aspects such as compressive strength, split tensile strength, flexural strength, modulus of elasticity, drying shrinkage, water absorption and temperature effect were studied. The use of thermal power plant by-products increases the strength at optimum replacement and decreases the shrinkage of concrete. The compressive strength was increased about 5.08% compared to normal concrete, where in case of split tensile strength it was increased by about 18.60% in Carbon Fibre Reinforced Concrete, flexural strength was increased by about 18.78% compared to conventional concrete. But shrinkage of concrete decreases because of presence of fibres.
With the ecological imbalance in nature due to exploitation of natural sand from rivers, it is important to utilise the industrial wastes to substitute the natural sand deficiency and to develop sustainable environment in construction industry. High strength and durability properties, key components of High performance concrete can be produced by using some admixtures like fly ash and silica fume. In the present study, fly ash and silica fume are taken as steady replacement of 15% and 10% respectively, for cement. Bottom ash is introduced in place of sand at the variations of 0%, 10%, 20%, 30%, 40% and 50%. Glass fibers of 1% are added as extra ingredient to improve some properties. The properties of strength, drying shrinkage and water absorption are studied for the M60 grade concrete designation. The results showed that the concrete with 40% bottom ash had the optimum strength.
Experimental investigation was carried out to determine the enhancement of compressive strength, flexural strength and abrasion resistance along with water permeability of porous concrete introduced with hybrid fibres (consists of equal proportion of steel, polypropylene and glass) and with two different sizes of coarse aggregate. The varying parameters in the preparation of porous concrete mix were coarse aggregate of two sizes, i.e., 6mm and 12 mm and five different percentages of hybrid fibres (0.25 - 0.65 with an increment of 0.1). Compressive strength and flexural strength were measured at the end of two curing periods (7 and 28 days) whereas water permeability and abrasion test values were measured at the end of 28 days of curing. From the experimental findings, it is observed that compressive strength and flexural strength values increase with decrease in the size of the aggregate for control as well as fibre reinforced porous concrete. However, with respect to the measured values of permeability, it is found that with increase in size of coarse aggregates, permeability values also increases. For 28 days samples it is observed that 0.35% addition of hybrid fibres to porous concrete found to be optimum and it improved the compressive strength values by 20.24% and 19.06% for coarse aggregate sizes of 6mm and 12mm, respectively as compared to porous control concrete (without addition of hybrid fibres). Whereas, maximum flexural strength was obtained at 0.45% of addition of hybrid fibres and 31.6% (6mm coarse aggregate) increment and 24.26% (12mm coarse aggregate) increment were noticed as compared to porous control concrete. The best values for permeability were found at 0.35% of hybrid fibres and 12 mm coarse aggregate combination, whereas for abrasion resistance it was at 0.35% of hybrid fibres and 6mm coarse aggregate combination.
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Volume - 93
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