Analytical and experimental investigation for bond behaviour of newly developed polystyrene foam particles’ lightweight concrete

Structural lightweight concrete (LWC) is of high importance to the construction industry, as it is cost effective and highly advantageous. A new kind of LWC was produced at the Department of Structural Engineering of Ain Shams University in 2005, which combines the advantages of normal density concrete, cellular concrete and high workability concrete through partially replacing the normal weight aggregates with polystyrene foam particles. This leads to concrete’s unit weight reduction while maintaining adequate strength. The latter material can therefore be produced using standard methods familiar to the construction industry with a dry unit weight of 18.50 kN/m3, which in turn leads to self weight reduction of 15–20% and the associated decrease in the structure’s overall cost, hence, providing a feasible challenge to normal weight concrete (NWC). The bond behaviour of structural polystyrene foam lightweight concrete (PF-LWC) was investigated analytically and experimentally. The experimental program incorporated two phases. The first phase was performed on the standard pull-out specimens to compare its results with the commonly conducted bond testing and to abstract the bond slip curve of the standard pull-out test specimens. The second phase deal with a deduced beam-end specimen to assess the behaviour of bond between reinforcing bars and concrete in flexure members. Then analytical investigation of the obtained experimental results was performed to develop a model capable of assessing the structural bond behaviour of PF-LWC flexural members. The defining parameters of the bond stress–slip curve were modified for NWC and PF-LWC using the best fit technique to the experimental results in order to add the bar diameter as a variable in the bond stress–slip relationship. The defining parameters of the CEB-FIP 1990 bond stress–slip curve [1] were modified for NWC and PF-LWC using the best fitting technique.