Erosion Phases in Two Types of Cement Pastes Containing Limestone Exposed to Sulfate Attack

Abstract:

Limestone filler and aggregates are used widely in cement production and concrete mixing nowadays, which could be connected with thaumasite formation, and lead to a lack of durability further. This work deals with the sulfate minerals including of thaumasite, ettringite and gypsum in two types of cement pastes containing 35% w/w limestone powder immersed in MgSO₄ solution at 5°C±2°C for 15 weeks by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). Two types of cements were used: (i) ordinary Portland cement (P·O), (ii) typeII Portland cement (P·II). Test results show that thaumasite is present in two types of cement pastes, amount of thaumasite as well as amount of portlandite reacted with external SO₄^2- in P·II cement paste are more than those in P·O cement paste. It indicates that P·II cement is more susceptible to thaumasite formation than P·O cement containing the same amount of limestone powder, and more gypsum formation could contribute to thaumasite formation possibly during the external MgSO₄ attack at low temperature.

• Periodical: Applied Mechanics and Materials (Volumes 584-586)
• Pages: 1182-1187
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.584-586.1182
• Online since: July 2014
• Authors: Feng Chen Zhang*, Yun Zhao, Fu Wan Zhu
• Keywords: Ettringite, Gypsum, Portlandite, Thaumasite

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