Physical, mechanical, and thermal properties of concrete roof tiles produced with vermiculite

This study aimed to evaluate the effect of using expanded vermiculite and its impact on the production of concrete roof tiles. The control treatment and replacement of 12.5, 25, 37.5, and 50% sand by vermiculite were evaluated. The concrete roof tiles were moulded by the simultaneous pressing and extrusion mechanical process. The control trace was comprised by 21.95% CPV-ARI cement, 65.85% sand, and 12.20% limestone. After production, the concrete roof tiles were cured for 28 days. The physical (roof tiles classification, samples dry weight, water absorption, and porosity), mechanical (splitting tensile strength), and microstructural properties were evaluated. All treatments were assessed before and after accelerated ageing. The thermal properties of the modification in the concrete roof tiles' composition were also analysed. The evaluated amounts of vermiculite significantly affected the physical, mechanical, and thermal properties of concrete roof tiles. The use of vermiculite in concrete roof tiles reduced their dry weight and thermal conductivity, not impairing their durability. The use of 31.0% vermiculite in concrete roof tiles was suggested for better thermal insulation optimization (20.29% reduction) and weight reduction (7.92% and 7.94% at 28 days of curing and after accelerated ageing, respectively), along with adequate physical, mechanical, and durability properties.

Lignocellulosic materials as soil-cement brick reinforcement

The need for environmental preservation requires civil engineering to reach new concepts and technical solutions aiming at the sustainability of its activities and products. In this context, this study aimed to evaluate the effect of using different types and percentages of vegetable particles on the physical, mechanical, and thermal properties of soil-cement bricks. Bamboo, rice husk, and coffee husk particles at 1.5 and 3% percentages and a control treatment not using the particle were evaluated. The chemical properties, shrinkage, compaction, consistency limits, and grain size were characterized for the soil; and the anatomical, chemical, and physical properties for the lignocellulosic particles. The bricks were produced using an automatic press and characterized after the curing process for density, water absorption, porosity, loss of mass by immersion, compressive strength, durability, and thermal conductivity. The increase in the lignocellulosic waste percentage caused a mechanical strength decrease and bricks' porosity and water absorption increase. However, it caused a decrease in density and an enhancement in loss of mass and thermal insulation properties. The bricks produced with rice husk obtained the best results in terms of mechanical and thermal properties, and were still among the best treatments for physical properties, standing out among the lignocellulosic waste as an alternative raw material source for soil-cement brick production.

Study of the use of polymeric waste as reinforcement for extruded fiber-cement

The disposal of post-consumption tires and plastics has become a significant environmental concern. New routes for recycling and using polymeric waste are needed since current treatment and disposal options do not reach the production of these materials. In this context, this study aimed to evaluate the effect of the use of tire and polyethylene terephthalate (PET) waste at different amounts on the physical, mechanical, thermal, and durability properties of extruded fiber-cement. Portland cement was replaced with 1, 2, 3, 4, and 5% by weight of polymeric waste from tire and PET. The fiber-cement was evaluated at 28 curing days and after accelerated aging, for density, water absorption, porosity, modulus of rupture, modulus of elasticity, proportionality limit, tenacity, and thermal conductivity properties. Tire and PET waste could be used as reinforcement material in fiber-cement, allowing for not only the correct destination and development of more sustainable new products but also the improvement of physical, mechanical, thermal, and durability properties of extruded fiber-cement.

Study of new reinforcing materials for cementitious panel production

The development of building materials using new types of raw materials is currently on demand by society and the industry. It is intended to reduce production costs, improve properties and obtain ever-increasingly sustainable processes and products. In this respect, this work aimed to evaluate the effect of new types of reinforcement material on the physical-mechanical and thermal properties of cement-based panels. Cement-based panels reinforced with pine wood, coffee husk waste, rice husk and polyethylene terephthalate (PET) were evaluated. The panels were produced with 1.30 g.cm^-3nominal density; 1:2.5 reinforcement material: cement ratio; 1:1.5 water:cement ratio; 0.25 cement hydration rate using Portland ARI V cement and 3% calcium chloride (CaCl₂) as additive. The panels' physical, mechanical and thermal properties were evaluated before and after accelerated aging. PET bottle wastes showed great potential for use in cement-based panel production, obtaining the best physical and mechanical results, and showing superior performance to pine wood panels. Cement-based panels reinforced with coffee husk and rice husk waste obtained lower physical-mechanical performance, presenting usage limitations, however, with the lowest values of thermal conductivity.