Concrete cured in extreme hot or cold conditions – such as you might find in a desert or above the arctic circle – can be significantly strengthened by adding sodium acetate to the mix, a new study shows.
Traditionally, curing concrete in extreme conditions results in a weakened structure – cold weather can cause small ‘micro-cracks’ to develop where the water in the mixture freezes, whilst hot weather can lead to weak bonds between the cement and the aggregates in concrete.
But now researchers at Brunel University London and Mutah University in Jordan have shown how adding sodium acetate not only significantly increases the compressive strength of concrete in extremes of warm or cool weather, but also reduces the amount of water the concrete absorbs, potentially paving the way for stronger concrete that requires less on-going maintenance.
The study – Development of low absorption and high-resistant sodium acetate concrete for severe environmental conditions – is available online from the journal Construction and Building Materials.
“Currently, most available protective additives in concrete reduce its compressive strength,” said Dr Seyed Ghaffar, an assistant professor at Brunel’s Department of Civil and Environmental Engineering, who authored the paper alongside colleagues Dr Mujib Rahman, Dr Omar Abo Madyan and Dr Mazen Al-Kheetan.
“Sodium acetate, on the other hand, has proven its ability to preserve and even increase the compressive strength of concrete under harsh weather conditions.”
To test their ideas, the researchers produced 72 concrete cubes with varying mixes of sodium acetate, which were then cured at either -25°c or +60°c for seven or 28 days.
“Results showed an enhancement of 64% in compressive strength when 4% sodium acetate is incorporated within the concrete and cured under 60°C,” said Dr Ghaffar.
“Also, water absorption was observed to decrease by more than 79% when 2% sodium acetate is added to concrete.”
The new study builds on previous work from Dr Rahman and Dr Al-Kheetan, who previously demonstrated how adding sodium acetate to concrete can protect it from the ravages of salt.
The team now hope to test how integrating sodium acetate in concrete affects the performance and durability of concrete in the long-term.
Tim Pilgrim, Media Relations
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