In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Become an ACI Member
Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
American Concrete Institute
38800 Country Club Dr.
Farmington Hills, MI
Feedback via Email
Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Delayed Ettringite Formation: Suggestion of a Global Mechanism in Order to Link Previous Hypotheses
Author(s): X. Brunetaud, L. Divet, and D. Damidot
Publication: Special Publication
Appears on pages(s): 63-76
Keywords: concrete; cracking; crystallization pressure; delayed ettringite formation; internal sulfate attack; mechanism of expansion
Abstract:Ettringite observed in macroscopic paste cracks during DEF is often held responsible for concrete deterioration. However, some authors have raised the hypothesis of an homogeneous paste expansion resulting from ettringite crystallisation in the C-S-H porosity, which does not attribute any mechanical effects to the subsequent formation of ettringite crystals in the voids. Thus the role of ettringite is still controversial. In this paper, we are tempting to link the two previous hypotheses in a more global mechanism: During heat treatment, thermal decomposition of ettringite can occur, whereas higher amount of sulphate and aluminate are trapped into C-S-H porosity. Then, at ambient temperature, ettringite forms in the porosity corresponding to the network of C-S-H layers. If the volume of ettringite reaches the limit of C-S-H porosity, the following ettringite crystallisation induces an homogeneous expansion of the paste. This expansion can generate peripheral cracks around aggregates. Then, the local shrinkage around voids resulting from the dissolution of the small ettringite crystals incorporated in C-S-H layers and the following precipitation of ettringite massive crystals in the cracks due to Ostwald rippening, outbreaks radial cracks. When the material is weaken by a multidirectional crack network, the pressure exerted by massive ettringite crystallisation can propagate existing cracks by strain localisation at the crack's tip, even if the crystallisation pressure is small in these conditions.
Click here to become an online Journal subscriber