Chloride transport in partially saturated mortar made of blended cement

Yong Zhang, Guang Ye

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

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Abstract

Due to environmental (low CO2 emission) and economic benefit, supplementary cementitious materials (SCMs) have been widely used in reinforced concrete structures. However, the question from engineering practice is to which extend these blended mixtures do meet the future durability criteria. Chloride ingression is nowadays considered as the main concern for reinforcement corrosion. Due to self-desiccation or drying process, cement-based materials are no longer saturated, which would greatly influence the chloride transport properties.
This paper explores the effect of water saturation level on chloride diffusivity in cement-based materials by resistivity measurements. Experiments were performed on mortars made of different blended materials, i.e. fly ash, blast furnace slag and limestone powder. Mortar materials have been curing for 200 days conditioning in humid room at 20±1°C, followed by oven drying at 50°C until the samples reach targeted water saturation levels. The results showed that chloride diffusivity is highly dependent on the water saturation level and water-vapour desorption isotherm of the mortar material. The dependency varies with cement type, and is significantly related to pore size distribution characteristics. In addition, the effect of water content on chloride diffusivity is more evident in blended cement mortars than reference ordinary Portland cement mortar. For the materials studied in this research, the capillary pores with diameter range of 7.1-73 nm plays dominated role in chloride diffusion under non-saturated state.
Original languageEnglish
Title of host publicationProceedings of the 14th International Congress on the Chemistry of Cement
Subtitle of host publicationBeijing, China
Number of pages10
Publication statusPublished - 2015
Event14th International Congress on the Chemistry of Cement - Beijing International Convention Center, Beijing, China
Duration: 13 Oct 201516 Oct 2015
Conference number: 14
http://iccc2015.csp.escience.cn

Conference

Conference14th International Congress on the Chemistry of Cement
Abbreviated titleICCC 2015
CountryChina
CityBeijing
Period13/10/1516/10/15
Internet address

Keywords

  • cement mortar
  • saturation degree
  • chloride
  • supplementary cementitious materials

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