Influência de ciclos molhagem-secagem em fibras de sisal sobre a aderência com matrizes de cimento Portland

Abstract

Aiming a reduction in the water absorption capacity of lingo-cellulosic fibers, wetting and drying cycles are usually performed in the industry of paper and cellulose. This procedure stiffens the polymeric structure of the fiber-cells (process known as hornification) resulting in a higher dimensional stability. In the present work it was investigated if the dimensional stability, obtained from the hornification process, can imporove the adhesion of the sisal fiber in a Portland cement matrix. In order to study the fiber-matrix bond adhesion pull-out tests were performed in embedment lengths of 25mm and 50mm. Furthermore, it was investigated the influence of the hornification in the physical behavior (dimensional variation and water absorption), me-chanical (behavior under tensile loading) and microstructural (surface modifications of the fiber and changes in the fiber-cell structure). The results indicate a higher dimensional stability, reduction in the water ab-sorption capacity, increase in the tensile strength and strain capacity and reduction in the modulus of elasti-city with the hornification. The pull-out load increased which indicates a higher bond strength in the horni-fied fiber with the cementitious matrix.