Influence of limestone additions on sulfate ingression

Author(s): B. Lothenbach, T. Schmidt, M. Romer
Paper category: workshop
Book title: Performance of cement-based materials in aggressive aqueous environments – characterization, modelling, test methods and engineering aspects
Editor(s): Nele De Belie
Print ISBN: none
e-ISBN: 978-2-35158-059-2
Publisher: RILEM Publications SARL
Pages: 45 - 52
Total Pages: 8
Language: English

Abstract: Mortar samples produced with Portland cements with 0, 5, and 25% of limestone showed differences in the porosity as well as in the ingression depth of the sulfate into the samples. In samples with 25% limestone, a faster ingression of sulfate was observed than in samples containing 5 or 0% limestone. Also a higher expansion and mass gain was observed for mortar prisms containing 25% limestone. Thermodynamic modelling was able to reproduce the sequence of the different layers formed upon the ingression of Na2SO4 solution. The same sequence of phases and a similar accumulation of SO3 near the surface were calculated as observed experimentally.

The addition of small amounts of limestone (≤ 5%) leads to a stabilisation of ettringite in the hydrated cement and to a decrease of porosity compared to Portland cements containing no limestone. Portland cements containing a few percent of limestone showed a better resistance against sulfate attack. The replacement of a higher fraction of the cement by limestone, however, led to an increase of the porosity of the hydrated cements and thus to a faster ingression of sulfate into the mortar.

Online publication: 2008
Publication Type: full_text
Public price (Euros): 0.00