Abstract
This paper presents the autogenic self-healing potential of Portland cement (PC) blends made with conventional supplementary cementitious materials (SCMs), to improve the water-tightness by reducing the overall pore size. Mortar samples were prepared by mixing PC, sand and water, and partially replacing PC by either silica fume (SF), pulverised fuel ash (PFA), or ground granulated blast-furnace slag (GGBS). Damaged samples were subjected to a water bath to heal microcracks and recover the water-tightness, by further hydration of the starting minerals. Water absorption and density measurements in undamaged, damaged and healed conditions were used to determine the autogenous healing potential of SCMs mixes, showing a post-healing absorption recovery of up to 68% compared to the mix with PC only. Thermal analysis, XRD and MIP measurements confirmed the capability of SCMs to promote the formation of hydrated phases, and reduce the overall pore size by more than 88% compared to PC mixes.
Highlights
Cracking, weathering and carbonation are but a few examples of the main causes of damage in concrete (Gardner et al, 1016)
The values obtained might not reflect the real compressive strength of the mixes, i.e. the sample size differs from the dimension recommended by the BS EN 196–1:2016, said values are a good estimation of the strength, in agreement with literature values for cement mortars incorporating supplementary cementitious materials (SCMs) (Benli and Bakir, 2017; Monteagudo et al, 2014; Almeida and Klemm, 2018)
A number of samples in series C, P, and B presented visible damage on the surface at low percentage of loading, and any further increase in load would have resulted in the sample
Summary
Cracking, weathering and carbonation are but a few examples of the main causes of damage in concrete (Gardner et al, 1016). When salts and water penetrate the pores, the pressure exerted during the salt crystallisation may cause damage to the concrete structure (Espinosa-Marzal et al, 2011). Whilst modern construction design practices take into account possible scenarios to minimise damages and increase the service life of concrete structures, their maintenance still represents an economical and environmental burden. Researchers have studied and developed technologies to provide crack-closure mechanisms without external intervention. -called self-healing concrete provides a solution to repair cracks at different temporal and spatial scales, and can potentially reduce an asset’s maintenance costs (Huang et al, 2016; De Belie et al, 2018; Sidiq et al, 2020)
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