Title: Drying Shrinkage in Alkali Activated Class C Fly Ash Mortars and the Mitigation Methods

Author(s): Darshan Ballekere Kumarappa, Chathurani Chandrasiri and Sulapha Peethamparan

Publication: Symposium Paper

Volume: 320

Issue:

Appears on pages(s): 10.1-10.12

Keywords: alkali-activated class C fly ash, drying shrinkage, alkaline activator, internal curing, polypropylene fibers

DOI: 10.14359/51701048

Date: 8/1/2017

Abstract:
The drying shrinkage of alkali activated class C fly ash (FAC) is quantified in this study in accordance with ASTM C490. The effect of activator concentration is evaluated by varying silica modulus (SiO2/Na2O) and Na2O contents. An ordinary portland cement (OPC) mortar mixture is also evaluated for the comparison purposes. In general, drying shrinkage is significantly higher in FAC mortars than in OPC mortar. Higher amounts of both silica modulus and Na2O contents result in greater drying shrinkage. Hydration kinetics and porosity are also evaluated to describe the higher drying shrinkage exhibited by FAC mortars. FAC mortars with a larger drying shrinkage exhibited a lower mass loss, a reverse trend normally exhibited by OPC mortars. Internal curing and discrete polypropylene fiber addition are evaluated as potential shrinkage reducing methods. The results show that both methods are efficient in reducing the drying shrinkage in FAC mortars.