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Compressive Strength and Drying Shrinkage of Alkali-activated Fly Ash/Slag Mortars

Maochieh Chi 1, Weichung Yeih 2, Jiangjhy Chang 2, and Kuochung Tsou 2
1. Department of Fire Science, WuFeng University, Chiayi County, Taiwan
2. Department of Harbor and River Engineering, National Taiwan Ocean University, Keelung City, Taiwan

Abstract— This study investigates the compressive strength and drying shrinkage of alkali-activated fly ash/slag mortars (AFSM). The liquid sodium silicate with modulus ratios (mass ratio of SiO2 to Na2O) of 2.5 were used as alkaline activators to alkali-activate fly ash and slag with various ratios of 50/50, 60/40, 70/30, 80/20 for fly ash to slag and liquid-to-binder ratios of 0.5 and 0.6. Test results showed that the compressive strengths decreased with an increase of FA and liquid-to-binder ratio for all AFSM. At the age 28 days, M5A (AFSM with fly ash/slag ratios of 50/50) has the highest compressive strength of 76.2 MPa. The drying shrinkage rate decreased with an increase of FA. At the age of 28 days, the drying shrinkage rate of M5D (AFSM with fly ash/slag ratios of 80/20) is 43.33 × 10-4, which has the lowest drying shrinkage rate for all AFSM. Based on the test result, both the fly ash/slag ratio and the liquid-to-binder ratio have a significant influence on the compressive strength and drying shrinkage rate of AFSM.

Index Terms—compressive strength, drying shrinkage, alkali-activated fly ash/slag, mortar

Cite: Maochieh Chi, Weichung Yeih, Jiangjhy Chang, and Kuochung Tsou, "Compressive Strength and Drying Shrinkage of Alkali-activated Fly Ash/Slag Mortars," International Journal of Structural and Civil Engineering Research, Vol. 9, No. 2, pp. 161-164, May 2020. doi: 10.18178/ijscer.9.2.161-164