White efflorescence on brick masonry and concrete masonry blocks, with special emphasis on sulfate efflorescence on concrete blocks

Efflorescence is widely known as an aesthetic problem of brick and block masonry fagades. Up to now no pragmatic remedy is found for this phenomenon. The appearance of white efflorescence depends on environmental circumstances, material parameters of bricks, mortar and concrete blocks including chemical composition, building details and way of execution, and may additionally be influenced by treatments of the fagade. The presented research focuses on the investigation of the efflorescence process and its relevant parameters. It aims at the development of test procedures for determination of the efflorescence risk and subsequently at the assessment of potential solutions for the problem. The research is carried out in several stages following a genetic approach based on primary analysis of field data. This article gives an introduction to the genetic types of efflorescence encountered during the field study, and a more detailed discussion of one special issue regarding the carbonation of ettringite as potential source for sulfate efflorescence. (C) 2004 Elsevier Ltd. All rights reserved.