Abstract
Capturing the long-term performance of concrete must be underpinned by a detailed understanding of the pore structure. Mercury intrusion porosimetry (MIP) is a widely used technique for pore structure characterization. However, it has been proven inappropriate to measure the pore size distribution of cementitious materials due to the ink-bottle effect. MIP with cyclic pressurization–depressurization can overcome the ink-bottle effect and enables a distinction between large (ink-bottle) pores and small (throat) pores. In this paper, pressurization–depressurization cycling mercury intrusion porosimetry (PDC-MIP) is adopted to characterize the pore structure in a range of cementitious pastes cured from 28 to 370 days. The results indicate that PDC-MIP provides a more accurate estimation of the pore size distribution in cementitious pastes than the standard MIP. Bimodal pore size distributions can be obtained by performing PDC-MIP measurements on cementitious pastes, regardless of the age. Water–binder ratio, fly ash and limestone powder have considerable influences on the formation of capillary pores ranging from 0.01 to 0.5 µm.
Highlights
It has long been considered that microstructural characteristics, which govern almost all the physical and chemical processes taking place in concrete, play a decisive role in the mechanical and durability properties of concrete
The alteration of water–binder ratio (w/b) or an addition of blended materials including fly ash and limestone powder will inevitably affect the pore structure of concrete because of the changes of particle packing and chemical composition as well as the changes to the hydration process
This paper aims to afford deeper insights into the pore size features of the cementitious system by adopting the pressurization–depressurization cycling cycling mercury mercury intrusion intrusion porosimetry porosimetry (PDC-Mercury intrusion porosimetry (MIP))
Summary
It has long been considered that microstructural characteristics, which govern almost all the physical and chemical processes taking place in concrete, play a decisive role in the mechanical and durability properties of concrete. Research on this topic has been the focus of considerable research effort, with special attention being paid to determine the pore structure. The alteration of water–binder ratio (w/b) or an addition of blended materials including fly ash and limestone powder will inevitably affect the pore structure of concrete because of the changes of particle packing and chemical composition as well as the changes to the hydration process. The micrometric capillary pores are interstitial spaces between unhydrated grains, usually irregular in shape, and represent the originally water-filled
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