Today researchers all over the world are focusing on ways of utilizing either industrial or agricultural wastes as a source of raw materials for the construction industry. This is used to minimize the emission of CO2 during the manufacturing of cement. One of the agricultural waste products is coffee husk which is found in large amounts in Ethiopia. This paper aims to characterize the physical and chemical properties of Coffee Husks Ash (CHA) by using X-ray diffraction (XRD), Scanning electron microscope (SEM), and Fourier Transforms Infrared Spectroscopy (FTIR) tests, and also the experiment were conducted to determine the compressive, split tensile and flexural strength of the material and durability tests were determined. The result have shown that, when the replacement percent further increases, the crystalline material increases, silicate concentration decreases, and also the micro pores or air void are increases, which may lead to decreasing the strength of concrete. In the case of mechanical property of concrete, there has been remarkable increment up to 5% CHA replacement and also strongly satisfied up to 10% replacement, furthermore increasing CHA replacement up to 20% are optimum dosage of normal concrete mix production of C-25 concrete. Finally, water absorption and sulfate attack of partially replaced concrete is shown as an improvement in the durability of concrete.
The objective of the study is a partial replacement of natural fine aggregate with crushed waste glass for M 30 concrete production. To determine the compressive strength of such concrete for using 10% 15%, 20%, and 25% of partial replacement including control samples using 0.45, 0.47, and 0.50 water-cement ratios. Quality tests, slump, compressive strength, density, permeability, and Ultrasonic pulse velocity test are performed; the cube of concrete mix design test follows the American Concrete Institution (ACI) guideline. And to develop a predictive model for the 7days and 28days compressive strength using a fuzzy model. The result has shown that the physical properties, of course, fine aggregate and crushed waste glass satisfy the standard specification, when the replacement percent increases, the compressive strength and ultrasonic pulse velocity of concrete are increased up to 15% of replacement level Due to the angular nature of waste glass particles contributes more effective cement past. Thus reduction of microscopic voids in concrete. The study also found the depth of penetration for concrete indicates the increased replacement percent increase in the depth of penetration increase due to increase microscopic void space. It was concluded that the natural sand is effectively partially replaced by crushed waste glass, maximum compressive strength was achieved at 15% of replacement level. The result showed that quite satisfactory in predicting the Compressive strength for 7 and 28 days strength of the M-30 concrete mix using the fuzzy logic technique with a coefficient of correlation, R2 of 0.87 and 0.85 respectively for training and validation set. The significance of the study is that the compressive strength of concrete made with partial replacement of natural fine aggregate by the crushed waste glass can be predicted by using the predictive model developed.
This research was carried out to consider the effect of different curing methods on the performance of concrete for grade 25 of normal concrete. The objective of this research was to determine the effect of different curing methods on the performance of concrete. This study considers the effect of five curing methods (air curing (B1), water submerged curing (B3), spraying curing (B2), burlap curing (B4) and moist sand curing (B5)) were used to evaluate the strength, carbonation, length change, absorption, and sorptivity of concrete on 3rd , 7th, 14th, 28th and 56th days at hot air temperature (18-390C) and medium air temperature (11.2-32.70C). A total number of 210 cube and 30 prisms samples were cast for all curing methods. The result indicated that water submerged curing was the highest strength of concrete followed by the close burlap, spraying, and moist sand curing methods of concrete. The air curing was the lowest strength of concrete and carbonated concrete in hot and medium air temperatures. The concluded weak positive correlation between the strength and the density of concrete. The strength strong negative correlation with length change, water sorptivity, and water absorption of concrete at hot and medium air temperatures. Finally, the water submerged and moist sand curing techniques were the appropriate techniques for off-site construction of concrete structures; and the burlap & spraying curing were suitable for off-site and on-site construction of concrete structural members in hot and medium environmental conditions.
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