In this study, different proportions of gypsum composite reinforced with recycled cellulose fibers and expanded polystyrene were produced to study the properties of thermal conductivity, density, and flexural strength to be used as sealing plates to improve the thermal comfort of buildings. Different gypsum matrix composites were produced with varied proportions of cellulose fiber and expanded polystyrene, to analyze the influence of residues on the properties of the material. The thermal conductivity obtained for composites with greater amounts of expanded polystyrene was 0.18 W/mK, a 48% reduction in relation to plasterboard, improving thermal performance. The flexural strength was also analyzed, which met the minimum strength requirement for use as gypsum composites, however, it is not enough to be used in places that require mechanical resistance, thus it is indicated for sealing plates applications, improving the thermal performance of places where only plasterboard is used.

Indian cedar (Acrocarpus fraxinifolius) is a wood species that occurs naturally in India, Myanmar (Burma) and Bangladesh, and has a high commercial value, with characteristics like mahogany and native cedars. The planting of Indian cedar has been undertaken in Brazil, but there is little information available regarding the characterization of the species. Therefore, considering its timber potential and its possibility of development in the country, the present work aimed to evaluate the physical, chemical, and mechanical properties of 9-year-old Indian cedar wood, planted in the southern region of Brazil. A low specific mass (502 kg/m³), low average dimensional stability (anisotropy coefficient of 2,09 %) was observed, in addition to the low content of extractives (1,94 %). From the mechanical characterization, an average value for the elastic modulus of 8963 MPa was obtained, and for the compressive strength parallel to the grain the average and characteristic values were 32,14 MPa and 21,46 MPa, respectively. This indicates that this wood belongs to resistance class C20 (dicotyledons). The results obtained classify the wood for use in light, external, or internal civil construction

This work physically, mechanically, and chemically characterized the composites produced from Portland CP II-E32 cement and fresh Indian cedar wood particles previously treated by immersion in hot and cold water. Density values for wood particulate composites were around 50% lower compared with the wood-free control treatment, from 0.88 to 1.78 g/cm³. A larger swelling was observed for the composite material. The results of compressive strength and stiffness indicated that there is no need for particle treatment for composite production. Hot and cold water immersion treatments reduced the total Indian cedar wood extractives by 33% and 42%, respectively. Optical microscopy analysis was used to identify adhesion failures between the cement/wood interface of the composite produced with fresh particles, which presented a higher percentage of extractives. This result indicated that the greater concentration of total extractives partially inhibits the matrix-matrix interaction reinforcement. Despite the reduction in total extractives caused by the treatments, this process is not necessary for the composite production because there is no statistical difference between the treatments. The values obtained for the composite indicate the possibility of application in sealing blocks in light construction systems.

Ensuring the quality of the connector used in wood–concrete composite systems is a critical factor affecting the performance of the system. The main objective of this research was to study the strength and stiffness of wood–concrete composite specimens with two types of rebar dowel connectors: fixed to the wood (solid timber) using epoxy adhesive and by pre-drilling on smaller diameter holes in the wood (without the use of adhesive). In the composition of the test specimens, rebar dowels of 12·7 mm dia. were used. The strength and stiffness of the connectors were determined by double shear tests, performed on composite specimens. Statistical analysis was used to compare the results obtained and regression models were proposed for estimating the stiffness parameters of the connections. The connectors glued with epoxy adhesive provided better strength and stiffness for the composite specimens when compared to the connectors fixed to the wood by pre-drilling. The differences between the strength and stiffness of the connection systems analysed were statistically significant. The regression models proposed presented a good approximation for the estimation of the Kser and Ku slip moduli of the composite specimens analysed.

Cement-based composites with lignocellulosic residues (e.g. wheat straw, rice husk, and bagasse) as fillers have reduced density and cost. Pretreatments have been applied in these raw materials to improve their compatibility with cement. This work aimed to characterize composites made from cement and wheat straw particles that had been chemically treated (2% NaOH solution) at two different temperatures (30 °C and 60 °C). Values of bulk density (209 kg·m-3) and specific density (679 kg·m-3) were determined for wheat straw at 12% moisture content. Straw yield was 71.9% and the particle size distribution showed large concentrations of wheat straw particulate material between 5- to 10-mesh. Composites made with wheat straw particles, in comparison to the control treatment, showed half the density, i.e., from 1800 to 900 kg·m-3. Also, the stress x strain curve presented a higher deformation before failure. NaOH pretreatment did not affect the mechanical properties of wheat straw composites.