Abstract
One approach to tackle the problems created by the vast amounts of construction and demolition waste (CDW) generated worldwide while at the same time lengthening concrete durability and service life is to foster the use of recycled aggregate (RA) rather than natural aggregate (NA). This article discusses the use of polyhydroxyalkanoates (PHAs)-producing mixed microbial cultures (MMCs) to treat the surface of recycled concrete with a view to increase its resistance to water-mediated deterioration. The microorganisms were cultured in a minimal medium using waste pinewood bio-oil as a carbon source. Post-application variations in substrate permeability were determined with the water drop absorption and penetration by water under pressure tests. The significant reduction in water absorption recorded reveals that this bioproduct is a promising surface treatment for recycled concrete.
Highlights
The great increase of the population and consequent increase of urbanization and industrialization require the use of a large volume of concrete [1,2]
The bioproducts used in this study to treat the surface of concrete specimens were generated by mixed microbial cultures (MMC)
Waste biomass from the reactor was added to water at a concentration of 2–10% to prepare two liquid bioproducts: SP (MMC sonicated to break down bacterial cell membranes) and NSP (MMC in which the suspension contained whole, nonsonicated cells)
Summary
The great increase of the population and consequent increase of urbanization and industrialization require the use of a large volume of concrete [1,2]. To meet these needs, the annual global concrete consumption is estimated to be about 25 billion tons [3]. The increased demand on concrete implies the need of large amounts of its major components, cement, water and aggregates. Aggregates represent 60 to 75% of the total volume [5], which accounted for around 40 billion tons in 2015, and is expected to rise to 47.5 million tons by 2023 [6]. The development of eco-friendly alternatives is a challenge for the concrete industry in many territories [8,9]
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