Influence of slag composition on cracking potential of slag-portland cement concrete. (10th March 2018)

• Record Type: Journal Article
• Authors: Markandeya, Ananya; Shanahan, Natallia; Gunatilake, Dhanushika Mapa; Riding, Kyle A.; Zayed, A.
• Is Part Of: Construction & building materials. Volume 164(2018)
• Page Start: 820
• Page End: 829
• Publication Date: 2018-03-10
• Subjects: Granulated blast-furnace slag -- Concrete -- Mechanical properties -- Calorimetry -- Rigid cracking frame -- Free shrinkage frame -- Porosity; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.12.216
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Early-age cracking risk was evaluated for slags with variable Al2 O3, MgO and fineness. All slags reduced temperature rise and improved cracking resistance. Cracking potential of slag concretes varied depending on slag properties. A linear relationship was observed between RCF indices and MgO/Al2 O3 and fineness. A decrease in the MgO/Al2 O3 ratio of the slag increased early-age reactivity. Abstract: Semi-adiabatic calorimetry and a rigid cracking frame were used to compare the effects of five different ground granulated blast-furnace slags with variable Al2 O3 and MgO contents, but similar CaO/SiO2 ratios on early-age cracking resistance. While cement replacement with slag significantly reduced concrete temperature rise and delayed the time of cracking compared to the plain concrete, it was observed that stress development varied with the MgO/Al2 O3 ratio of the slag. Increasing this ratio reduced the cracking temperature and delayed the time of cracking. The worst performance of the low MgO/Al2 O3 ratio slag was attributed to its higher early-age reactivity, which was confirmed by isothermal calorimetry in addition to its higher autogenous shrinkage assessed by free shrinkage measurements.