Plastic shrinkage cracking performance of mortars with ground granulated blast-furnace slag (GGBS) modified by superabsorbent polymers (SAP)

Fernando C.R. Almeida, Agnieszka J. Klemm, Valeria Corinaldesi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Abstract

Ground granulated blast-furnace slag (GGBS) is a popular supplementary cementitious material widely used to improve durability and sustainability of concrete and mortars. However, its filler effect, trigged by GGBS delayed setting, may lead to increased cracking susceptibility. Plastic shrinkage cracking performance is directly related to its excessive drying of exposed surfaces during the first hours of setting. In an attempt to reduce this negative effect, Superabsorbent polymers (SAP) can be used as internal curing agents. This paper aims to analyse the efficiency of SAPs in reducing plastic shrinkage and hence in mitigating cracks formation in PC-GGBS mortars. Three types of SAPs with different water absorption capacity were used. Mortars specimens were subjected to specially designed severe conditions of restraint and moisture loss during the first 24h after mixing. Cracking patterns were analysed by optical microscopy and image processing software. Evaporation rate (by water loss mass) and setting times (by Vicat apparatus) were also tested. The results showed that SAPs addition reduces up to 90% of plastic shrinkage crack widths (for lower GGBS contents). Only above 50% of GGBS substitution, visible cracks can be observed in SAP mortars.
Original languageEnglish
Title of host publicationRILEM Proceedings PRO 125
Subtitle of host publication4th International Conference on Service Life Design for Infrastructures
PublisherRILEM
Number of pages14
ISBN (Electronic)9782351582138
Publication statusPublished - 29 Aug 2018

Keywords

  • plastic shrinkage
  • cracking
  • mortars
  • ground granulated blast-furnace slag
  • GGBS
  • superabsorbent polymers
  • SAP

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