Topic
Ettringite
About: Ettringite is a research topic. Over the lifetime, 2702 publications have been published within this topic receiving 67056 citations. The topic is also known as: woodfordite.
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TL;DR: In this article, a second-order chemical reaction between reacting calcium aluminates and ingressing sulfates depletes the sulfate concentration, leading to changes in the diffusivity and a reduction in the elastic properties of the matrix.
Abstract: A chemomechanical mathematical model is presented to simulate the response of concrete exposed to external sulfate solutions. The model is based on the diffusion-reaction approach, and several mechanisms for the reaction of calcium aluminates with sulfates to form expansive ettringite are considered. Fick’s second law is assumed for diffusion of the sulfate ions. A second-order chemical reaction between reacting calcium aluminates and ingressing sulfates depletes the sulfate concentration. The products of the second-order reaction between the aluminates and sulfates are chosen among several competing mechanisms, and a rule-of-mixtures approach is used to relate the expansive nature of the products with the prescribed specific gravity of the compounds. It is furthermore assumed that the crystallization pressure of products of reaction results in a bulk expansion of the solid. The constitutive response of the matrix and the expansive stresses are calculated from the imposed volumetric strain. Microcracks are initiated when the strength of the matrix is reached, leading to changes in the diffusivity and a reduction in the elastic properties of the matrix. The variation of diffusivity is linked to the scalar damage parameter due to cracking of the matrix. Due to the changes in the diffusivity, the problem is treated as a moving boundary problem, and a methodology is proposed to adapt the solution of the 1D case to the 2D problem of a prismatic specimen. Theoretical expansion-time responses are obtained and compared with a variety of data available in the literature.
235 citations
TL;DR: In this article, the sulfate resistance of blended Portland cement with fly ash and ground rice husk ash (RHA) was studied, and it was shown that RHA was more effective than fly ash in reducing the expansion of the mortar bars and the pH values.
232 citations
TL;DR: In this article, XRD measurements of the hydration of synthetical cement (SyCem) were used to calculate the resulting heat flow from changes in the phase content, and the comparison with data recorded from heat flow calorimetry was in good agreement with the calculated heat flow.
229 citations
TL;DR: In this article, the thermal behavior of hydration products in ordinary Portland cement as a function of age was investigated using differential scanning calorimeter (DSC) and X-ray diffraction analysis.
228 citations
TL;DR: In this article, the authors investigated the corrosion of different hardened cementing materials, such as Portland cement (PC), alkali-activated blast furnace slag cement (ASC), lime-fly ash (LFA) blend and high alumina cement with gypsum and lime (HAC), in pH 3 nitric acid, pH 3 acetic acid, and pH 5 acetic acids solutions, and found that PC pastes were corroded faster than ASC and LFA pastes, and pastes consisting of HAC were quickly dissolved in these acid solutions.
226 citations