Adobes reforçados com palha de carnaúbas [copernicia prunifera (Miller) H. E. Moore]

Abstract

The traditional construction system in the state of Piauí is still an alternative in rural communities. These architectures of earth present low resistance to the humidity, as a result, the interest arose for the use of fibers of the carnauba straw as reinforcement in the production of adobe bricks. The objective of this research was to study the stabilization of adobe brick with the addition of carnauba straw fibers, a species native to the Piauí flora. To prepare the adobe bricks were added carnauba straw fiber: 1% w/w (N1), 5% w/w (N5), 10% w/w (N10) and control pattern (C). The adobe bricks were manually consolidated and then were allowed to dry at room temperature. In this work, the results of bulk density, relative shrinkage, compressive strength and capillary water absorption are presented. The statistical treatment was performed through the ASSISTAT version 7.7 program with variance (1% probability) and Tukey test (5% probability). The highest fiber content's adobe brick formulations was found to be slighter: C (1,88 g/cm3 ), N1 (1,76 g/cm3 ), N5 (1,54 g/cm3 ) and N10 (1,30 g/cm3 ). The addition of the fibers was significant in the reduction of shrinkage of groups N5 (6,09%) and N10 (5,08%), when compared to samples C (13,92%) and N1 (12,16%). Sample N10 presented compressive strenght value of 4,68MPa and samples C (1,42 MPa), N1 (1,35 MPa) and N5 (1,70 MPa) had very close in compressive strength values. The results that showed lower water absorption coefficients were C (0,0350 kg/m2 .√s) and N1 (0,0454 kg/m2 .√s), followed by N5 (0,0696 kg/m2 .√s ) and N10 (0,0868 kg/m2 .√s). However, the bricks of adobe N5 and N10 remained intact during the immersion for 24 hours, compared to the others that disintegrated partially or totally. As a consequence, the addition of carnauba straw fibers was generally favorable to 10% w/w adobe brick that presented better mechanical properties.