The Influence of Fly Ash Addition on the Compressive Strength of Concrete Containing Recycle Concrete Aggregates

Abstract

The rapid economy growth in Indonesia encourages the developments in all fields. One of them is the development of infrastructure on housings, transportations, and irrigation. Constructions of concrete building are used on the road, bridges, buildings, housing, and water buildings. A concrete is a material structure of building that made from mix of sand, gravel, cement and water as adhesive. All the materials of the concrete were derived from the nature. To avoid the excessive exploration of nature resource the method of recycling of used concrete to become new one were needed. The used concrete was used for coarse aggregate. To improve the quality of concrete from the used one, additional material was required, that is, fly ash. The test material were formed of cube of 15x15x15 cm in size. From the result of research, the analysis can be done in order to find the relationship between quantity of fly ash to be added and the quality of concrete can be formulated as y =-34.921x2 + 11.45x + 25.465, in which y is compressive strength and x is the percentage of fly ash. Thus, for maximum addition of fly ash of 16.4 %, it obtains the maximum compressive strength of concrete of 26.4 MPa and the age of concrete is 28 days. The method of recycling of used concrete and the use of fly ash to become the material of new concrete are safe environmentally, which can overcome the nature filthy especially from the waste of used concrete and coal. Therefore, this is in line with the principal of nature preservation, those are Reduce, Reuse dan Recycle.