Comprehensive investigation of butyl stearate as a multifunctional smart concrete additive for energy‐efficient buildings

Abstract

Summary Using of phase change materials (PCM) for increasing energy savings in sustainable buildings is receiving a lot of interest in commercial applications. Butyl stearate (BS), as PCM, can be used to maintain ambient temperature in the human comfort zone and prevent temperature fluctuations by enhancing the thermal properties of concrete. The long‐term effects of BS on concrete are not well known. In this study, the applicability of BS, as a smart concrete additive, by direct incorporation in the concrete structure was investigated comprehensively including thermal, rheological, and corrosion behaviour. The thermal characterization of PCM was achieved using DSC, TGA, thermal conductivity, and thermal buffering experiments. Thermal storage capacity of BS was measured to be 134.2 J/g, which is high enough to be used for passive solar energy storage in buildings. The fresh concrete experiments revealed that workability and flowability of fresh concrete mixes were improved. The maximum hydration temperature was reduced, and a retarding effect was observed by the addition of BS. Moreover, the corrosion behaviour of steel embedded in concrete with BS as PCM was studied in a solution of NaCl (3.5 wt%) representing an aggressive environment by utilizing electrochemical impedance spectroscopy (EIS) for long‐term corrosion tests that lasted for 1 year. The open circuit potential of steel in concrete with BS showed noble potential indicating low corrosion probability. The FESEM images and polarization resistance (Rp) values showed that the addition of BS in concrete decreases corrosion of the rebar in comparison with concrete without BS. Addition of BS not only enhances thermal capacity but also exhibits corrosion protection of rebar by hindering penetration of chloride ions into the concrete.

Preparation, characterization, and thermal properties of novel fire-resistant microencapsulated phase change materials based on paraffin and a polystyrene shell

“…In recent passive building applications, PCM is incorporated into concrete to increase energy density and efficiency. [5][6][7][8] One problem of direct use of PCMs in building materials is leakage from the porous structure, which might result in spreading the re much faster. Hence, the recent trend is microencapsulating PCMs to avoid leakage problems.…”

Core@double‐shell structured multifunctional phase change microcapsules based on modified graphene oxide Pickering emulsion

“…3 This material has been used in construction, 4 heat pump system, intelligent spinning, and biological materials. [5][6][7][8][9] However, organic Pn is easy to diffuse and leak, and low thermal conductivity and other issues limit the scope of application of PCMs. 10 In recent years, people have taken some measures and solutions to these problems.…”

Enhancement of thermal properties of bio-based microcapsules intended for textile applications

“…Organic PCMs can be divided into main parts, such as pure alkanes, paraffins, fatty acids and their derivatives, and polyols [7]. Researchers used a broad range of PCM materials such as eicosane [8], n-octadecane [9], fatty acids, such as stearic acid, palmitic acid, myristic acid, and lauric acid, and their blends [10,11], polyethylene glycol (PEG-100) [12], PEG 100 with Na-alginate [13], paraffin and nanomagnetite [14], butyl stearate [15], and others. Organic PCMs are a particularly well-suited candidate for energy storage owing to their especially high latent heat.…”

“…It is common knowledge in heat transfer that when lateral surface area increases, the heat transfer rate also increases [15]. Consequently, rod-type fins, such as carbon nanotubes, could perform better than plate-type ones, for example, expanded graphite or exfoliated graphite nanoplatelets.…”