Effect of permanent forms of cementitious composites with short sisal fiber on the shear of reinforced concrete beams

Resumo

Traditional form systems for reinforced concrete structures, produced in steel and wood, have some
deficiencies from the point of view of cost, environment and management. The use of permanent form systems
for beams, produced with cementitious composites reinforced with short sisal fibers, can bring improvements to
the production process and influence the mechanical behavior of the beam when they are subjected to shear
efforts. In this work an experimental investigation of the influence of the permanent forms is made when the
reinforced concrete beam is subjected to shear forces. 8 beams were produced, 2 of them for control and 6 beams
with permanent form. Such forms were produced with 3 composites with short sisal fibers in different levels and
different water/binder ratios. The beams were tested by bending at 3 points with asymmetric load and part of the
beam was produced without stirrups in order to more easily verify the influence of the form. It was observed that
the use of the forms brings improvements in the mechanical behavior, with slightly higher maximum loads,
higher energy absorbed and a lower level of opening in the cracks caused by the shear.