Heat-induced explosive spalling of self-prestressing, self-compacting concrete slabs

A novel concrete mix has been developed that can achieve high levels of self-prestressing through the controlled expansion sample with cast-in carbon fibre reinforced polymer (CFRP) bars. Experiments have shown mechanical properties and durability are not adversely affected by mix’s self-expanding nature. However, behaviour this at elevated temperatures is largely unknown, raising legitimate concerns regarding fire performance resulting self-prestressed elements. The research presented in paper investigates elements manufactured from self-prestressed, self-compacting (SPSCC) when exposed to severe heating – such as would likely be experienced during a building fire. Nine specimens, dimensions (600 mm × 200 45 mm) were tested under one-sided exposure an experimentally simulated ISO 834 standard regime. results showed SPSCC samples acutely prone explosive spalling these conditions. also suggest comparatively higher moisture content samples, compared conventional mixes similar composition properties, appeared most critical factor for heat-induced cover spalling. Higher prestress (compressive) forces exacerbate likelihood samples. addition 2 kg/m3 polypropylene (PP) fibres led complete elimination self-prestress PP 30 % less than those without fibres, reasons which require additional investigation. Differential thermal between internal CFRP bars was observed restrain elongation curvature heating, up until point where debonded surrounding due temperature (presumed) increased tensile stress tendon anchorage zones. provide compelling evidence supporting need include within high-performance, self-prestressing, slabs.