US EPA

6863751 

Journal Article 

The influence of aluminium on the dissolution of amorphous silica and its relation to alkali silica reaction 

Chappex, T; Scrivener, KL; , 

2012 

Yes 

Cement and Concrete Research
ISSN: 0008-8846 

PERGAMON-ELSEVIER SCIENCE LTD 

OXFORD 

1645-1649 

10.1016/j.cemconres.2012.09.009 

WOS:000313154700009 

It is known that the addition of supplementary cementitious materials (SCMs) in concretes reduces or even stops expansion due to alkali silica reaction (ASR). It has been widely shown that the main mechanism controlling ASR in blends is the alkali fixation capacity of silica rich C-S-H, which lowers the pH of the pore solution. The role of alumina additions is less clear. It was shown in a previous paper [1] that the alumina present in certain SCMs does not further reduce the alkalinity of the paste pore solution. It is proposed here that aluminium acts directly on the reactive phases of the aggregates. Aluminium species, present in the pore solution, are absorbed on the silica surface and limit the dissolution of amorphous silica of the aggregates, restricting ASR. The effect of aluminium was demonstrated through a study of mortar expansion and SEM image analysis of reactive aggregates in simulated pore solutions. (C) 2012 Elsevier Ltd. All rights reserved.