High performance lightweight concrete - a comparison between actual prestress losses and design code estimates

Abstract

Two different high performance lightweight concretes (HPLC) with strengths of 55 and 69 MPa were developed. They had an air-dry unit weight of 1855 and 1890 kg/m3, respectively. Creep, shrinkage and prestress losses were investigated on 36 cylinder specimens and on four AASHTO Type II girders. Prestress losses measured on the AASHTO Type II girders made with HPLC were less than those predicted using AASHTO, PCI and ACI-209 methods which means that the design codes give conservative estimates of the actual prestress losses of this new concrete. Based on experimental data, final, total prestress losses were estimated to be 14.3 and 9.6 % of the initial prestressing force for the 55-MPa and 69-MPa HPLC, respectively.