Simplified method for concrete pavement design with discrete structural fibers

摘要

The addition of discrete macro fibers to plain concrete increased the fiexural capacity of concrete slabs supported on ground. Flex-ural strength tests (i.e., ASTM C78) did not capture the added toughening mechanisms fibers imparted to concrete slabs. Based on the results of small and large-scale testing, the equivalent flexural strength ratio (R_(e.3)) was used to quantify the increased fiexural capacity of synthetic and steel-fiber reinforced concrete slabs over plain concrete slabs. An effective fiexural strength approach was proposed for the design of fiber-reinforced concrete pavements. The method applied a percentage increase to the modulus of rupture (MOR) of plain concrete based on the measured R_(e.3) value for the fiber-reinforced concrete mixture. The effective MOR accounts for the contribution of fibers to the added slab fiexural capacity and fits into existing linear elastic-based design guidelines for concrete pavement. Large-scale test results verified the proposed design approach for fiber-reinforced concrete pavements. The proposed method is applicable for concrete mixtures reinforced with relatively low volume fractions of fibers that produce R_(e.3) values between 20% and 50%. Such fiber concrete mixtures are practically and economically attractive as they can be mixed, placed, and compacted with normal paving techniques.