Mechanical properties, phase composition and microstructure of activated Metakaolin-slaked lime binder

Abstract

In the present paper mechanical properties, microstructure and phase composition of binder produced by mixing Metakaolin (MK) and slaked lime in 4:1 proportion by weight have been studied. Anhydrous Gypsum was mixed as an activator in different percentages of 0%, 5%, 10%, 15% and 20% by weight of the binder. The study measures the changes in the physical properties, flexural and compressive strengths of the mortar at different ages of curing varying from 2 to 28 days. Binder and sand were mixed in 1:1.5 proportion for the mortar preparation. Superplasticizer Glenium 51 was added by 1% weight of the binder. The curing of demolded mortar specimens were done at room temperature for 2 to 28 days. The optimal dosage of anhydrous gypsum was found as 5% by weight of the binder at which bulk density, compressive and flexural strengths of mortar were maximum and the total porosity and water absorption were minimum. Addition of 5% anhydrous gypsum increases the compressive and flexural strengths by 68.5% and 72.1% respectively. The composition and microstructure of the mortar confirm the trend of variation of mechanical properties of the mortar.