Experimental Investigation on Environmentally Sustainable Cement Composites Based on Wheat Straw and Perlite

Abstract

Environmentally sustainable cement mortars containing wheat straw (Southern Italy, Apulia region) of different length and dosage and perlite beads as aggregates were prepared and characterised by rheological, thermal, acoustic, mechanical, optical and microstructural tests. A complete replacement of the conventional sand was carried out. Composites with bare straw (S), perlite (P), and with a mixture of inorganic and organic aggregates (P/S), were characterised and compared with the properties of conventional sand mortar. It was observed that the straw fresh composites showed a decrease in workability with fibre length decrease and with increase in straw volume, while the conglomerates with bare perlite, and with the aggregate mixture, showed similar consistency to the control. The thermal insulation of the straw mortars was extremely high compared to the sand reference (85–90%), as was the acoustic absorption, especially in the 500–1000 Hz range. These results were attributed to the high porosity of these composites and showed enhancement of these properties with decrease in straw length and increase in straw volume. The bare perlite sample showed the lowest thermal insulation and acoustic absorption, being less porous than the former composites, while intermediate values were obtained with the P/S samples. The mechanical performance of the straw composites increased with length of the fibres and decreased with fibre dosage. The addition of expanded perlite to the mixture produced mortars with an improvement in mechanical strength and negligible modification of thermal properties. Straw mortars showed discrete cracks after failure, without separation of the two parts of the specimens, due to the aggregate tensile strength which influenced the impact compression tests. Preliminary observations of the stability of the mortars showed that, more than one year from preparation, the conglomerates did not show detectable signs of degradation.

Recycled Materials in Civil and Environmental Engineering

“…In the papers by Petrella and coworkers [ 8 , 9 ], industrial and agricultural by-products such as end-of-life tire rubber and wheat straw were used as aggregates for the production of unconventional cement mortars prepared by a cheap and environmentally safe process. The artifacts resulted in thermal insulating with respect to the sand-based references, while the presence of another aggregate as perlite was used to improve the mechanical strengths with no detrimental effects on the thermal conductivities due to the porous nature of the inorganic material [ 10 , 11 ].…”

Conservation Environments’ Effect on the Compressive Strength Behaviour of Wood–Concrete Composites

“…They also offer additional benefits, such as good phonic insulation due to their ability to absorb sound waves [ 34 , 35 , 36 ]. Another significant advantage of using wood filler in cementitious materials is its cost; it is readily accessible, ecologically acceptable, and simple to process [ 37 , 38 , 39 ]. However, the primary challenges faced throughout numerous studies of wood–concrete products have been the compressibility of the wood particles inside the hardened concrete due to their low level of stiffness [ 40 ] and the incompatibility induced by soluble chemicals during the fresh cement phase [ 41 ].…”

Experimental investigations on water absorption and mechanical properties of expanded perlite mortar under accelerated and natural aging conditions

“…Thus, it is not possible to compare and analyze the effects of artificially accelerated aging and natural aging. Petrella et al [25] evaluated the acoustic, thermal, optical, and mechanical properties of mortar with different perlite content. However, the aging trend of expanded perlite mortar performance was not determined.…”