A state-of-the-art review on delayed ettringite attack on concrete英文电子资料.pdf

Cement Concrete Composites 25 (2003) 401–407 /locate/cemconcomp A state-of-the-art review on delayed ettringite attack on concrete M. Collepardi * Civil Engineering Faculty, Leonardo Da Vinci, Politechnic, Milan, Italy Abstract The paper presents a critical review of the sulphate attack related to ettringite formation. This process is associated with ex- pansion. However, not necessarily any ettringite-related expansion is related to the sulphate attack. For example, early ettringite formation which occurs immediately (within hours) in a plastic fresh mixture does not produce any damaging expansion and is associated with the regulation of setting time of Portland cement paste. Expansion after the hardening of cement paste can be advantageously used for the development of chemical prestress in expansive cements. Delayed ettringite formation (DEF) occurs at late ages and the related heterogeneous expansion in a hardened concrete can produce cracking and spalling. Two different types of DE Fare examined depending on the sulphate source: DE Fcaused by external sulphate attack or internal sulphate attack. 2003 Published by Elsevier Science Ltd. Keywords: Delayed ettringite formation; Expansion; Sulphate attack 1. Introduction 2. Ettringite formation Ettringite formation is considered to be the cause of Ettringite formation is associated with expansion and most of the expansion and disruption of concrete many hypotheses of ettringite related expansion have structures involved in the sulphate attack [1]. Howe