Enhancement of the structural efficiency and performance of concrete pipes through fiber reinforcement

• Performance of different synthetic fibers in dry-mix concrete were evaluated.
• High elastic modulus fiber enhanced engineering properties of Concrete pipe.
• The number of steel reinforcement layers can be reduced through the use of polyvinyl alcohol (PVA) fibers in concrete pipes.
• PVA fibers could enable reduction of pipe thickness, thus lowering of the overall weight of concrete pipes.

Fiber reinforcement systems are used towards development of pipes with more efficient structural designs, reduced steel reinforcement, increased cover thickness over reinforcement (and thus durability), reduced weight, streamlined geometry (for ease of handling and installation), and enhanced shear resistance. Comprehensive experimental investigations were undertaken to evaluate the efficiency of different synthetic fibers (aramid, AR-glass, carbon, and polyvinyl alcohol (PVA)) at various volume fractions (0.5–1.0 vol.%) in lean, zero-slump concrete materials used in dry-cast method of concrete pipe production. PVA fiber was used for use in concrete pipes due to its desired balance of reinforcement efficiency and stability in aggressive chemical (e.g. sanitary sewer) environments. The reinforcement efficiency of PVA fibers in concrete was attributed to its relatively high elastic modulus and desired interfacial bonding to cement hydrates. Industrial-scale structural evaluation of concrete pipes indicated that 30% improvement in load-carrying capacity of concrete pipes was realized with introduction of PVA fibers. This improvement enabled reduction of welded wire fabric steel reinforcement layer in concrete pipes from two to one, thus increasing the protective concrete cover thickness over steel and durability of concrete pipes under the aggressive exposure conditions of sanitary sewers. Theoretical models were also developed for predicting the contributions of PVA fibers to the structural performance of concrete pipes. Comparison between experimental results and theoretical predictions indicated that experimental results occur within ±10% of theoretical predictions. The thickness of concrete pipes could also be lowered with introduction of fibers, thus reducing of the overall weight, and thus the production, transportation and installation costs of concrete pipes.