Use of alternative aggregate for lightweight concrete production

Abstract

The search for new material sources that meet the assumptions of sustainable development is constant, especially in the civil construction industry. Therefore, the objective of the present research was to develop and characterize physically and mechanically lightweight bio-concretes produced with an alternative lignocellulosic source. Cereus jamacaru (Cactus) wood was used as a bio-aggregate after washing in hot water (80 °C). Chemical and physical characterization of the aggregate were performed. A cement based matrix was developed using Portland Cement (CP V-ARI), a water-to-cement ratio of 0.4 and calcium chloride (3% bwc). Mixtures with two types of wood particles classified as green and brown were produced and for both cases several percentages of compensation water (100 and 200%) and cement / wood ratio (3, 4 and 7) were used. To characterize the mixtures in the fresh state a flow table test was performed. The mechanical characterization was performed by a uniaxial compression. The modulus of elasticity and density were determined. The density of the composites with the brown particles ranged from 892 to 1452 kg/m³ and the compressive strength of 3.38 to 10.51 MPa. The bio-concretes with green particles reached values between 872 and 1347 kg/m³ of density and between 1.72 and 8.94 MPa of compressive strength. The mixtures with higher cement/wood proportions and lower amount of compensating water reached higher compressive strength, as expected. The specimens with fixed consumption of 775 kg/m³ achieved better resistance/density ratio which is a property of great interest in engineering civil. The results showed that Cactus Wood can be used in the production of bio-concretes with good properties and varied applications in civil construction.