Low clinker high performance concretes and their potential in CFRP-prestressed structural elements

Abstract

Three novel low-clinker-high-performance concretes (LCHPC) with clinker replacement levels of 54, 58 and 70% were developed to substitute high-performance concrete (HPC) in carbon-fiber-reinforced-polymer (CFRP) prestressed structural elements. The clinker substitution was achieved by a high amount of limestone filler and smaller amounts of metakaolin and silica fume. After 28 days, the LCHPCs reached high compressive strength values, between 77 MPa and 88 MPa, and Young's moduli between 35 GPa and 44 GPa. The LCHPCs showed self-compacting properties and low creep and shrinkage in comparison to a reference HPC.A finite element analysis (FEA) of the internal stress development over time in CFRP-prestressed structural elements was performed, including creep and shrinkage. A higher prestress level was maintained in the LCHPCs compared to the reference concrete, thanks to their low shrinkage and creep. In contrast, the use of ultra-high-modulus CFRP prestressing tendons leads to increased pre-stress losses.