Strength and hygrothermal performance of low carbon insulation materials made of lime ternary binders and miscanthus particles: Miscrete

This paper examines the strength and hygrothermal properties of a novel bio-based building material made of miscanthus particles and lime-based ternary binders. Six types of lime binders were studied, including combinations of calcic lime (C), calcic lime and natural hydraulic lime (CN), lime-GGBS (CNG), lime-fly ash (CNF), a blend of lime and ‘rapid-setting’ cement (CNCe), and formulated Tradical PF70 (FLA). Binder to aggregate (b/a) ratios of 1.5 and 2.0 were analysed. The addition of supplementary cementitious materials in CNG, CNF, and CNCe resulted in higher compressive strength values (fc) measured at 28 days and for 5 % strain under room curing conditions. Binding systems C and CN reached only 31.4 and 27.8 kPa, whereas CNF and CNCe systems achieved strength values of 37.2 and 60.5 kPa respectively, and FLA mixes achieved 207 kPa. Reducing b/a from 2.0 to 1.5 decreased the compressive strength from 207.8 to 206 kPa at 28 days and from 481.5 to 364.8 kPa at 90 days. A consistent dry thermal conductivity in the range of 0.067 – 0.081 W/m·K, a water vapour permeability of 2.32E-11–3.89E-11 kg/(m·s·Pa), and a water vapour resistance factor of 5.14–8.49 were measured. The material achieved moisture buffer values (MBV) of 2.06–2.25 g/(m²·%RH), and thus it can be classified as an ‘excellent’ humidity regulator according to NordTest classification.