Abstract
Fly ash is a by-product of coal combustion in a power station and usually used as additive or cement replacement material to improve properties of concrete in aggressive environments such as acid, chloride, and sulphate. Peatland is one of acidic environment that is common in Riau province with high organic content and low pH that is damaging for concrete, especially when exposed to concrete at an early age. This paper aims to study the early compressive and tensile strength of the various type of fly ash based concrete subjected to peat water. Seven fly ash-based concrete mixtures investigate were, i.e., geopolymer hybrid using 15% of Ordinary Portland Cement (OPC) as an additive, high volume fly ash using 25%, 50% and 75% of fly ash as cement replacement material, and blended OPC with fly ash with different grade of 15, 21 and 29 MPa. The OPC concrete with a target strength of 20 MPa was a control mix. The OPC based-specimens were cast and cured in water for 28 days before placed in peat water for another 28 days before the testing date. Compressive strength and tensile strength values of the concrete at 7 and 28 days were taken. Results show the type of concrete, fly ash content, and concrete grade significantly influence the early strength properties and resistance of the concrete to the acid attack. Four concrete mixtures with decreasing vulnerability to the attack were distinguished: OPC, high volume fly ash, geopolymer hybrid and blended cement concrete.
Highlights
Degradation due to acidic attack is one of the most significant durability problems of structural concrete
The high volume fly ash was prepared by using different fly ash content up to 75%, and the blended cement was made by using different concrete grade
It can be seen that the compressive strength increased with concrete age for all concrete except for the Ordinary Portland Cement (OPC) mixture
Summary
Degradation due to acidic attack is one of the most significant durability problems of structural concrete. Acid from natural and industrial areas such as organic acid and sulfuric acid is known as the cause of loss strength, and the increase of porosity. Riau province has approximately 4 million hectares peatland [2]. Fast-growing regency cities in Riau require a large number of infrastructure that could be built in the peatland. The peat has a disadvantage such as high organic content, high water content, low pH and low bearing capacity [3] and can be improved by consolidation, stabilization, and cut and https://doi.org/10.10 51/matecconf /201927601022 fill. Continuous degradation will cause premature deterioration and reduction of serviceability of structures in peatland
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