Abstract
With the increasing trend of high-rise, large-scale, and functional modern architectural structures, lightweight aggregate (LWA) concrete that exhibits excellent strength and high functionality has garnered active research attention. In particular, as the properties of concrete vary considerably with the raw materials and the proportions of aggregates in the mix, in-depth research on weight reduction, strength improvement, and functional enhancements of aggregates is crucial. This study used the negative pressure coating of a mixed solution comprising epoxy (mixture of epoxy resin and crosslinker), hyper-crosslinked polymer, and titanium oxide (TiO2) nanoparticles on the LWA, and achieved an improvement in the strength of the LWA as well as a reduction in air pollutants such as NOx and SOx. Compared to a normal LWA with an aggregate impact value (AIV) of 38.7%, the AIV of the proposed epoxy–TiO2-embedded high-strength functional LWA was reduced by approximately half to 21.1%. In addition, the reduction rates of NOx and SOx gases resulting from the photocatalytic properties of TiO2 nanoparticles coated with epoxy were approximately 90.9% and 92.8%, respectively. Epoxy–TiO2, embedded in LWAs through a mixture, exhibited stability, high strength, and a reduction in air pollutant characteristics, despite repeated water washing. The LWA proposed herein offers excellent structural and functional properties and is expected to be used in functional lightweight concrete that can be practically applied in high-rise and large-scale architectural structures.
Highlights
Lightweight aggregate (LWA) concrete, which is lightweight yet strong, has received increasing attention owing to the accelerating trend of high-rise, large-scale, non-standardized, and specialized building structures
TiO2 NPs as a photocatalyst were mixed with an epoxy solution to remove NOx and SOx, which are typical air pollutants
When the prepared epoxy–TiO2 composite solution is embedded in the lightweight aggregate (LWA), the composite solution cannot penetrate into the pores owing to the presence of air, and it only coats the outer surface of the aggregates
Summary
Lightweight aggregate (LWA) concrete, which is lightweight yet strong, has received increasing attention owing to the accelerating trend of high-rise, large-scale, non-standardized, and specialized building structures. When LWAs are mixed with cement, the aggregates act as reinforcements and fillers for concrete, improving its strength and reducing its weight. The self-weight of the structure and the cross section of the structural members can be reduced along with improvements in the exclusive space of the structure and earthquake resistance. Artificial LWAs have received attention from precast concrete industries, such as panels with higher insulation and structural elements including walls and slabs, because the lower density of LWA concrete can lead to lower-cost transportation and easier handling in the construction site. Compared to natural LWAs, artificial LWAs generally have a low strength due to high moisture absorption [1]. The specific gravity, strength, Polymers 2020, 12, 2384; doi:10.3390/polym12102384 www.mdpi.com/journal/polymers
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