PROPERTIES OF CONCRETE UTILIZING SELFCEMENTING HIGH-CALCIUM FLY ASH AS SOLE BINDER MATERIAL

22 sep 2022

Jurnal Teknologi Full Paper

PROPERTIES OF CONCRETE UTILIZING SELFCEMENTING HIGH-CALCIUM FLY ASH AS SOLE BINDER MATERIAL

Oswyn K. Wattimena , Antoni Antoni , Djwantoro Hardjito

Department of Civil Engineering, Petra Christian University, Surabaya, East Java, Indonesia

https://doi.org/10.11113/jurnalteknologi.v84.17973

Abstract

Fly ash, a waste material derived from the coal burning in power plants, could be utilized in concrete mixtures as a filler or as a cement replacement material, either partially or fully. Some papers also report that high-calcium fly ash can be utilized as a cementitious material through the hydration process. However, there are just a few papers that studied the behavior of concrete that utilizes high-calcium fly ash as the sole binder material without any chemical activators. Furthermore, there are no reports about whether the effect of the different water-tocementitious ratios of this concrete is the same as the ordinary Portland cement concrete. This paper presents an initial development on the use of fly ash as a sole binder material, i.e., 100% fly ash concrete without any chemical solution as an activator. This research utilizes the high calcium content in the fly ash to produce concrete with a commonly used method (just add the water without any alkali activator) and investigates how the water-to-cementitious ratio can influence the compressive strength of the paste and the concrete as well. The calcium content in the fly ash used in this study was in the range of 19– 22 percent of the total weight of fly ash. Paste compressive strength of 66.78 MPa was obtained at 28 days with a very low water-tocementitious ratio of 0.110; on the other hand, the concrete compressive strength of 37.05 MPa was obtained at 28 days with a water-to-cementitious ratio of 0.143 and continued to increase to 49.78 MPa at 365 days. This research proved that the calcium content in highcalcium fly ash can act as self-cementing material and has the potential to be a sole binder material in concrete.

Keywords: High-calcium fly ash, self-cementing, very low water-tocementitious ratio, workability, slump loss, compressive strength

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