Pavements made with HPFRCC

Concrete has been used widely in construction of roads, highways, industrial floors and pavements since early twentieth century. Different construction methods include placement of joints after specific distances to control the transverse and longitudinal cracking due to the development of tensile stresses caused by the shrinkage of concrete and environmental factors such as temperature variation and moisture gradient. Such joints result in reduced load carrying capacity, joint failure and damage to the pavement reinforcement. As an alternative, jointless pavements can be used to reduce the joints as much as possible by adding fibers in ordinary concrete which will increase the tensile strength of the concrete, hence avoiding cracks. Stress strain models available for conventional concrete cannot be extended to UHPC or HPFRCC. This thesis aims to describe a possible model to be used for HPFRCC as proper modeling and design guides are needed for the development of HPFRCC joint free slabs in order to address and minimize potential cracking due to drying shrinkage. A composite cross section made of concrete and soil is assumed which is subjected to an imposed strain as dry shrinkage strain and using Colonette’s theory of elastic coactions the state of stress and strain in the concrete is calculated. Maximum tensile strain in the model is limited to the strain which produces localization and hence the cracking in the slab is avoided. This procedure is repeated for HPFRCC slab at different ages and the maximum tensile strains allowed by the concrete are compared with the maximum strains provided by the model to design the ultimate slab thickness by avoid cracking. To verify the reliability of the proposed model a possible test method is described to be used in future.