Naslov
Residual fracture properties of normal- and high-srength concrete subject to elevated temperatures

Autori
Zhang, B. ; Bićanić, Nenad ; Pearce, C.J. ; Balabanić, Gojko

Izvornik
Magazine of Concrete Research (0024-9831) 52 (2000), 2; 123-135

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
concrete; elevated temperatures

Sažetak
The effects of elevated temperatures (T_m) related to exposure period (t_h) and the curing age (t_a), on the residual fracture properties of normal-(NSC) and high-strength(HSC) concrete were investigated by conducting three-point bending tests on 87 notched preheated beams. Most beams were exposed to temperatures between 100C and 600C for 12 to 14 days, while some NSC beams were heated either for various exposure periods up to 168 h at 14 days or for 12 h at 7, 28 and 90 days. The weight loss (omega)was also monitored. The measured residual properties included the energy parameter (fracture energy G_f), a number of strength parameters (compressive strength f_c, tensile strength f_t and modulus of rupture f_r), stiffness parameters (Young's modulus E_c and Poisson ratio ni) and the brittleness parameter (the characteristic length l_ch). omega increased with T_m and t_h but decreased with t_a. There existed a transition point for omega at 200C which could mark a distinction between physical and chemical processes. G_f increased with T_m and omega up to 300C and then decreased. G_f also increased with t_h at lower temperatures but decreased az higher temperatures, and increased with t_a as well; f_c, f_t and f_r did not change very much with T_m up to 200C and decreased thereafter. A longer t_h had an increasing effect on all strengths at lower temperatures but a damaging effect at higer temperatures. All strength parameters increased with t_a. E_c and ni decreased continuously with T_m, t_h and omega. E_c increased whereas ni decreased with t_a. The concrete became less brittle with increasing T_m, t_h and omega or with decreasing t_a. In this study, all fracture parameters tended to become stable at 90 days. Finally, a linear relatioship between G_f and f_c existed not only for room temperatures but also for higher temperatures.

Izvorni jezik
Engleski

Znanstvena područja
Građevinarstvo

POVEZANOST RADA