Performance of blended metakaolin/blastfurnace slag alkali-activated mortars. (August 2016)

• Record Type: Journal Article
• Authors: Borges, Paulo H.R.; Banthia, Nemkumar; Alcamand, Himad A.; Vasconcelos, Wander L.; Nunes, Eduardo H.M.
• Is Part Of: Cement & concrete composites. Volume 71(2016)
• Page Start: 42
• Page End: 52
• Publication Date: 2016-08
• Subjects: Alkali-activated materials -- Geopolymers -- Concrete durability; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2016.04.008
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: This paper studies the effect of silicate content on the mechanical and durability-related properties of metakaolin (MK) and metakaolin/blastfurnace slag (BFS) alkaline activated mortars. A reference mortar based on the alkaline activated MK was compared to 60/40 MK/BFS mortars containing different SiO2 /Na2 O molar ratios in the activator. The properties assessed were compressive strength, porosity (water saturation), porosity and pore size distribution by Mercury Intrusion Porosimetry (MIP) and water capillary sorption. The microstructure was assessed using SEM and x-ray computerized micro-tomography (μ-CT). Results show that the addition of BFS significantly alters the microstructure of alkali-activated mortars, promoting a reduction of porosity and capillary sorption. In addition, an optimum SiO2 /Na2 O molar ratio in the activator is required to produce better durability mortars, which however do not necessarily present the highest mechanical strength.