STRENGTH VARIATION OF BLENDED MIX BY SELFING AND CROSSING THEORY

Abstract: Concrete is one of the most widely used construction material having ingredients as cement, fine aggregate, coarse aggregate and water. It develops strength in the presence of water when added to the dry mixture of the ingredients. The development of strength in the said mass starts instant of the time when the water is just added to it up to a certain time preferably the initial setting time and the prepared mass remains plastic and can be moulded easily, after which the hardening process proceeds faster towards the final setting time and the mass becomes hard and solid which cannot be moulded at all. Delays in concreting are leading to partial setting of concrete which has suffered a long period of exposure in the open before actual casting in the mould. This concrete should not be utilized for strength purpose in practice, and is to be discarded, but still it contains a good portion of the active part of the reactive cement in that mass. These situations may affect the strength of final product. The strength also depends on the plane at the concrete joint made while casting. If blending of such partially set concrete with richer mix to attain the target strength, can achieve economy and there will be no wastage of material. Much building waste is made up of materials such as concrete and mortar damaged or unused fur various masons during construction. Observational research has shown that this can be as high as 5 to 10% of the materials that go into a building a much higher percentage than the 2.5-5% usually assumed by quantity surveyors and the construction industry. Since considerable variability exists between construction sites, there is much opportunity for reducing this waste and by reusing the material natural resources and the environmental balance can be maintained and economy will be gained. The study aims for identifying such a time lag after that the required target strength may be achieved even after delay in casting. To identify the meeting planes of two interface layers which has lesser effect on compressive strength. Use of Bonding Agent (SBR Latex) for improves time lag and strength of concrete. Study of Blended of concrete (Selfing and Crossing).

Keywords: Selfing, Crossing, Blended Mix Concrete, Stryine Butdine rubber, Ultimate Load.