Abstract
A novel approach has been presented to add a dual‐crystalline hydrophobic admixture in fresh concrete for improving hydrophobicity against chloride and harmful chemicals. Dual‐crystalline material can utilize water of the fresh concrete to form crystals, but the challenge is to maintain adequate hydration and strength while improving hydrophobicity. This study presents the results from a comprehensive laboratory investigation on the application of 1, 2 and 8% of crystallizing aqueous and cementitious hydrophobic mineral in fresh concrete. Despite the high slump in the fresh mixture, no segregation was observed in the matured concrete. There was a marginal reduction of strength when a high percentage of admixture was used. Despite this, significant reduction of water absorption was observed indicating greater hydrophobicity. The optimum performance was found in mixtures with 2% admixture. Mixture with 2% aqueous hydrophobic admixture revealed marginal strength gain compared to 2% crystalline cementitious hydrophobic admixture, although water protection appears to be better in cementitious mixture.
Highlights
Concrete is known for its long serviceability, its performance could be greatly compromised when exposed to a harsh environment like bridges, concrete pavements, and coastal defenses
The purpose of this study is to investigate the performance of a crystallizing material mixed at mixing stage, in different percentages, within the concrete mixture
All the cubes are left for a duration of 24 hr to ensure that concrete has set and become stiff and ready to be demolded, except for the cubes with 8% admixture content, as they need more time to set, they were demolded after 72 hr
Summary
Concrete is known for its long serviceability, its performance could be greatly compromised when exposed to a harsh environment like bridges, concrete pavements, and coastal defenses. The deterioration is mainly caused by excessive water, chloride penetration and attack by other harmful substance like chemicals, fuel spillage, etc. In the United Kingdom, for example, there are about 61,000 highways and bridges, most of them are reinforced concrete pavements with reinforced steel, their maintenance expenses reached more than £4 billion in the period 2012–2013.1,2 They are subjected to rainfall of 1,420 mm as recorded in the year 2012, and about 1,120 mm in 2014.3,4 The easy
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