Multifunctional smart concretes with novel phase change materials: Mechanical and thermo-energy investigation

Abstract

Energy performance in buildings and integrated systems represents a key aspect influencing anthropogenic emissions worldwide. Therefore, novel multifunctional materials for improving envelope thermo-energy efficiency through passive techniques are presently attracting notable researchers' effort. In this view, the integration of phase change materials (PCM) into structural concrete showed interesting effects in enhancing the material thermal capacity while keeping proper structural strength. This work presents a multiphysics thermo-mechanical investigation concerning innovative concretes incorporating paraffin-based PCM suitable for structural-thermal multifunctional applications in high-energy efficiency buildings. Both classic microPCM-capsules and the novel more pioneering macroPCM-capsules with 18°C phase transition temperature are used for the new composite preparation. Results confirm the thermal benefits of PCM and demonstrate that the addition of PCM reduces the mass density of concrete by almost twice PCMs weight. Average compressive strength decreases with increasing the amount of PCM, but its coefficient of variation is not as negatively affected, which is promising in terms of structural reliability. Indeed, a 1% weight content of microPCM and macroPCM results in reduced coefficients of variation of the compressive strength, determining an increase in characteristic 2 compressive strength. This benefit might be associated to both a filler effect of the PCM and to a positive thermal interaction between inclusions and cement hydration products. The multifunctional analysis showed promising performance of PCM-based macro-capsules as aggregates, even if their concentration is relatively minor than the classic micro-capsules already acknowledged as effective additives for high energy efficient cement-based materials.

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

“…The thermal mass and energy storing capacity can be improved with the addition of PCM into concrete . Heating curves can be used to monitor the melting behaviour of PCM and calculate the stored energy in concrete specimens.…”

“…The buildings must possess durability and also provide thermal comfort to the users. Recent innovative approaches are trying to find new additives for concrete that will offer multiple benefits to the buildings . These additives should be compatible with concrete and not accelerate the corrosion of steel embedded in concrete.…”

Form‐stable Na 2 SO 4 ·10H 2 O‐Na 2 HPO 4 ·12H 2 O eutectic/hydrophilic fumed silica composite phase change material with low supercooling and low thermal conductivity for indoor thermal comfort improvement

“…The enormous progress of the economy and the rapid rising of human living standards have motivated the demand for indoor thermal comfort (22°C to 28°C), which leads to the increase in energy consumption . It is estimated that more than 40% of the entire energy consumption in the world results from building energy consumption, especially from ventilation, air‐conditioning, and heating consumptions closely related to indoor thermal comfort . Accordingly, to reduce the energy consumption of maintaining indoor thermal comfort, the building energy efficiency needs to be maximized.…”

Characterization of novel shape‐stabilized phase change material mortar: Portland cement containing Na 2 SO 4 ·10H 2 O and fly ash for energy‐efficient building

“…According to current research, the addition of encapsulated PCM can normally cause damage to the mechanical properties of concrete. D'Alessandro et al used classic PCM microcapsules to process a macroscopic capsule incorporated into concrete and compared it with classic microcapsules. The mechanical properties of concrete was improved by the microaggregate effect of PCM; however, the amount of PCM incorporated was limited (less than 3%).…”