Title: Effect of Magnesium Sulfate and Sodium sulfate on the Durability Performance of Plain and Blended Cements

Author(s): Omar Saeed Baghabra, Al-Amoudi, Mohammed Maslehuddin, and Mahmoud M. Saadi

Publication: Materials Journal

Volume: 92

Issue: 1

Appears on pages(s): 15-24

Keywords: blended cements; cements; concrete durability; expansion; magnesium sulfates; sodium sulfates; strength; sulfate attack; Materials Research

DOI: 10.14359/1173

Date: 1/1/1995

Abstract:
In this investigation, mortar specimens made with two plain cements, Type I and V, and blended cements, made with fly ash, silica fume, and blast furnace slag, were exposed to sodium-sulfate and magnesium-sulfate solutions. The performance of these cements, in both the environments, was evaluated by measuring expansion and determining reduction in compressive strength. The data indicate that while the performance of all blended cements, particularly those made with silica fume, was generally excellent in the Na 2SO 4 environment, their performance in the MgSO 4 environment was not satisfactory. A similar trend was observed in mortar specimens made with a water-cement ratio of 0.35. The type of cement did not have any significant influence on the performance of either plain or blended cements in both environments. The deterioration of both environments is attributed to the initial reaction of both solutions with calcium hydroxide (CH). The reduction of CH in blended cements provides an opportunity to react more directly with the primary and secondary calcium silicate hydrate (C-S-H) due to the destabilization of these phases by magnesium hydroxide (MH). Comparatively, lower deterioration of blended cements exposed to environment is attributed to the reduced CH, which significantly mitigates the sulfate attack in these cements.