The use of rubber in self-compacting concrete is gaining more attention from the point of view of improved engineering properties of the product and also sustainability. Although several attempts have been reported on the utilization of crumb rubber for the replacement of coarse aggregate in conventional concrete and to some extent in self-compacting concrete, limited information is only available on the use of rubber as replacement for fine aggregate. This article mainly deals with the development of self-compacting concrete with varying proportions of powdered rubber as filler (fine aggregate replacement). The self-compactability characteristics and the engineering properties of self-compacting rubberized concrete mixes with varying compressive strengths have been experimentally evaluated. The experimental values have been compared with those of conventional rubberized concrete available from the past studies. The results indicate that self-compacting rubberized concrete has better engineering properties, which are most desirable for structural purposes, in comparison with conventional concrete with and without rubber.
The major problem of the world is facing today is environmental pollution. It is well known that for the production of 1-ton of cement consumes more energy and exhibit 0.8-ton of CO2 .On the other hand Fly ash is a residue from the combustion of pulverized coal from the flue gases of thermal power plant. Recently, the fly ash is not effectively used and a large part of it is disposed in landfill. Due to this problem the various researchers have sort for a new binder to minimize the consumption of OPC. This study evaluates the strength of geopolymer concrete having fly ash as the major binding material and the sand a fine aggregate was replaced with copper slag of 40% and glass fiber to enhance the mechanical properties have been presented. This paper analyses on the mechanical properties of eopolymer concrete composites such as compressive strength, split tensile strength and water absorption in heat curing at 60˚C for 24 hrs in hot air oven. Glass fibers were added in the mix in the volume fraction of 0.5%, 1.0%, 1.5% and 2.0% volume of the concrete. The influence of fiber content in terms of volume fraction on the compressive, split tensile strength of geopolymer concrete is presented. The result shows the elevated performance of the properties exhibited by the geopolymeric concrete with and without fibres.
Aggregates generally occupy 60% to 75% of the concrete volume and strongly influence the fresh and hardened properties and economy of concrete. The continued extraction of aggregates from nature has caused its depletion at an alarming rate. The worldwide depletion of natural resources and the simultaneous accumulation of waste materials call for the need for sustainable development in the construction industry. Hence, recent researches have been focussed on the use of locally available waste materials such as coconut shell, plastic, etc., in concrete to replace the mineral aggregates. This study deals with the strength characteristics of PET fibre reinforced coconut shell concrete (PFRCSC). Earlier studies have shown that when coconut shell was used in concrete to replace the coarse aggregates, compressive strength was decreased considerably. But, this reduction in strength was significantly low for 10% coarse aggregate replacement. Also, the inclusion of polythene fibres made from waste plastic bottles was noted to improve the strength characteristics of concrete. Hence, an attempt has been made to combine the positive characteristics of both coconut shell concrete (CSC) and PET Concrete. M30 normal concrete and CSC concrete with 10% coarse aggregate of normal concrete replaced by coconut shell has been taken as thecontrol mixes. PET fibres made from waste plastic bottles were added at volume fractions of 0, 0.5, 1, 1.5 and 2%. The mechanical properties such as density, compressive strength, tensile strengthand flexural strength were determined and compared with the control mixes. The experimental investigations were carried out on a total of 180 specimens which includes cubes, cylinders and prisms. The results indicate that PFRCSC is a sustainable, eco-friendly and economical concrete with better engineering properties and strength characteristics in comparison with normal concrete and coconut shell concrete.
Structural insulated panels (SIPs) made by sandwiching an insulating material from both sides have been used in buildings to enhance thermal resistance without loss in structural integrity. New innovations to improve its compositeness are also being explored. One method is to use shear connector made of high thermal resistant and ductile materials. This connects two outer wythes through insulation layer. The outer material can be of any type of high compressive strength concrete. These are usually reinforced with steel or carbon or glass fiber. The use of light weight and high strength materials helps to reduce the overall thickness of the structure. As the material of shear connector acts as a thermal bridge across the outer wythes, materials with low U value (thermal transmittance) are preferred. In this paper, an attempt has been made to carry out a comparative study on the performance of SIPs with shear connectors manufactured using different materials.
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