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Abstrak :
Concrete is a composite building material. Due to its increasing demand in the construction industry, its basic ingredients such as cement, fine aggregate and coarse aggregate have become extremely costly. Studies have been carried out to find better and more economical alternatives to these conventional building materials. One such alternative is fly ash, which can be used to partially replace cement. The main disadvantage of conventional concrete is its brittle failure, which can be avoided by using steel fibers. This study identifies the behavior of concrete with regard to impact resistance and its mechanical properties by adding hooked-end steel fibers at levels of 0, 0.75, 1.15 and 1.55% and partially replacing 40% of the cement with 40% fly ash. In addition to the control concrete, there has been four mixes with respective addition of steel fibers. The behavior of normal and fly ash concrete with steel fibers was compared. The combination of fly ash and steel fibers provided a homogeneous and very rich mix, with a delay in the setting time of the concrete. Of all the mixes, the one containing 40% fly ash and 1.55% steel fibers proved to be the best, with a maximum increase in strength of 17% in compression, 25% in split tension, 30% in flexure and 95% in impact energy at 56 days. A multiple linear regression model was also formulated using SPSS (Statistical Package for Social Sciences) software, through which corresponding equations were developed to predict the strength and energy at 28 and 56 days. The equations were also used to predict the strength of the mixes from other researchers’ experimental work. The predicted results corresponded well with the experimental results and the percentage difference was found to be less than 5%.

Abstrak :
Concrete is a favoured building material due to its ease of production and use. Even though the concrete mix is designed to have a uniform strength throughout the entire member, casting, as well as the basic characteristics of the concrete materials, could yield a non-homogeneous constitution, resulting in a concrete strength gradation as a function of the depth of the member. A functionally continuous and smooth strength gradation of the concrete member along its axis or section is defined as graded concrete. The objective of this research is to analyse the influence of two different concrete compressive strengths that composed the graded concrete member. The study is split into two parts: the experimental work describing and identifying the mechanical properties of functionally graded concrete and the finite element analysis implementing these property variations in a model. The results showed that the concrete gradation influenced the ultimate strength of a member negatively and altered the stress distribution and displacement response of the specimen.

Abstrak :
Pemanfaatan potensi bahan bangunan lokal berupa limbah batu bara dalam pembuatan bahan bangunan ekologis menjadi salah satu bentuk dukungan terhadap konsep konstruksi ramah lingkungan.