Bio based concrete with crushed rape straw, a good alternative to develop an affordable bio based concrete for construction and renovation

Abstract

The renewable character is one of the major assets of the plant. The various studies consider an increasing development of biobased materials in the construction in the coming years, but it seems that the plant resources type hemp and flax are relatively limited in quantity and surface cultivated. The rarity which can lead to an inappropriate financial speculation, the development of an organic resources sector large-scale thus pass by the use of compatible layers in terms of available resources. While hemp and linen represent respectively approximately 12 000 the Ha/year and 80 000 the Ha/year, the rape is in France cultivated on about 1 600 000 Ha in 2014. These works were thus carried to characterize the rape straws for applications similar to those already used for hemp and for the flax. This study will be centered on the use of the particles with a diameter of 0-35 mm, resulting from the crushing of the rape straw collected into Picardy. The results obtained in this phase of characterization of the raw material, showed that the crushed rape straw have interesting properties, so much on the dry density (ρ = 65 kg m-3), that from the point of view thermal performances (λ = 0.046 W.m-1. K-1). The use of the untreated rape straw aggregates with a lime binder of the type Tradical PF70 allowed to show the possibility of a total substitution of the hemp by this type of vegetable particles. Indeed, they have a lower density and better thermal properties. As for their mechanical performances, they are comparable to those some concrete of hemp. The Life Cycle Assessment (LCA) indicators have also been calculated to prevent any environmental problems, and a Volatile Organic Compound (VOC) analysis gave a “A+” mark according to the French regulation of construction products.