Use of permanent ferrocement forms for concrete beam construction

Abstract

The results of an experimental investigation to examine the feasibility and effectiveness of using precast U-shaped ferrocement laminates as permanent forms for construction of reinforced concrete beams are presented in this paper. The precast permanent ferrocement forms are proposed as a viable alternative to the commonly used wooden and/or steel temporary forms. The experimental program comprised casting and testing of three control reinforced concrete beams of dimensions 300 × 150 × 2000 mm and eighteen beams of total dimensions of 300 × 150 × 2000 mm consisting of a reinforced concrete core cast in a precast U-shaped permanent ferrocement form of thickness 25 mm. Each control beam was reinforced with two steel bars of 12 mm diameter at the top and bottom of the beam and stirrups of 10 mm diameter placed at 200 mm intervals. The concrete core of the beams incorporating permanent ferrocement forms was reinforced with two steel bars of 12 mm diameter placed at the tension side of the beam without any stirrups. Three types of steel mesh were used to reinforce the ferrocement laminate. These types are: woven wire mesh, ×8 expanded wire mesh, and EX156 expanded wire mesh. Single layer and double layers of each type of the steel mesh were employed. All specimens were tested under three-point flexural loadings. The performance of the test beams in terms of strength, stiffness, cracking behavior and energy absorption was investigated. The results showed that high serviceability and ultimate loads, crack resistance control, and good energy absorption properties could be achieved by using the proposed ferrocement forms.