Impact of innovative additives on mechanical properties and long-term performance of lightweight concrete in sustainable residential construction projects

Lightweight concrete is the building block of energy-efficient home construction, but its ability to be lightweight, provide adequate load capacity, and provide long durability requires constant struggle to be used extensively in structural applications. It evaluates trade-offs of four novel additives that can be incorporated into perlite lightweight concrete for eco-friendly houses, such as hydrophobic silica aerogel, chopped basalt fibre, microencapsulated phase change material and colloidal nanosilica. The additives were individually tested and also in an optimized 4-ary additive system. We used a controlled factorial design to create 12 combinations, which we characterised using companion envelope energy modeling. We studied these mixtures in various aspects, including fresh, mechanical, thermal, durability, and microstructural properties. The optimized quaternary mixture showed 109% of the control's 28-day compressive strength and 86.9% of the control's freeze-thaw resistance after 300 cycles, while providing a 44.1% reduction in thermal conductivity compared to the control. Aerogel regulated insulation with an obvious strength loss; phase change material provided latent storage; basalt fiber provided tensile ductility; and nano-silica provided density of the interfacial zone, which enhanced the strength up to 21%. A variance-based sensitivity investigation showed that the nano-silica and aerogel fractions were the most important, and analysis of variance confirmed that all additives were statistically significant (at p < 0.001) for the main responses. This is the first study to combine all four additives in an optimized quaternary lightweight concrete, and it is the first to demonstrate the repeatability of the structural–thermal balance using combined sensitivity and Monte Carlo analysis under realistic production variability. Repeated performance was achieved through a Monte Carlo robustness evaluation of the output coefficient of variation, resulting in a minimum coefficient of variation below 5.1% for input disturbances of ±5%. The 35% energy saving of the annual envelope energy consumption indicates that the lightweight concrete with the proper proportions and using multi-additives can easily achieve the thermal efficiency needed in the domestic field.