Thermal-acoustic-mechanical performance of a lightweight cementitious matrix composite reinforced with rice husk

Aiming to develop a new product with good thermal-acoustic-mechanical performance to serve as an alternative to the materials commonly used for sealing, a composite was fabricated from a light cementitious matrix and rice husk. The cement matrix consisting in a cement paste with incorporated air, titled by several researchers as cellular concrete, presents main characteristics such as low specific mass and the large number of non-interconnected small pores. In turn, the rice husk is a vegetal fiber derived from the residue of rice production abundant in the Rio Grande do Sul state, the largest national producer of the grain. The cellular concrete and the composite (cellular concrete plus rice husk) were tested for mechanical resistance by single axial compression and by acoustic and thermal performance. Regarding the compressive strength, although the rice husk had a negative influence on the product, the both materials reached respectively the minimum strengths of 1.20 MPa and 1.50 MPa stipulated by NBR 13.438 and NBR 15.270, however, only the matrix (cellular concrete) hit the 3.00 MPa required by the NBR 6136. For the acoustic test, the composite obtained a better performance in acoustic absorption; on the other hand, concerned with the acoustic insulation the two materials did not present statistically difference, thus, one is impossible to affirm which one is better. About, the thermal conductivity, the composite with rice husk presented inferior performance to the matrix, which would be attributed to the high organic matter content present in the fibers.