Effects of Elevated Temperatures on Mechanical’s concrete specimen behaviour

Abstract

Abstract. This paper presents an experimental study on the performance of concrete, subjected to high temperatures. Investigation was carried out by using two mixtures: an Ordinary Concrete (OC) and High Performance Concrete (HPC) with 10% of Silica Fume (SF) replaced of cement weight and 1,5% of super plasticizer, the water-binder (w/b) ratio used was 0,5 and 0,32 respectively. The produced concrete specimens are heated at a rate of 7 °C/min up to different temperatures (150, 300, 450, 600 and 900°C). In order to ensure a uniform temperature through the specimen, the temperature is held constant at the temperature stage for one hour before cooling. Mechanical properties at ambient temperature and residual mechanical properties after heating have already been determined. We examined also the effect of high temperature on the aggregate-cement paste interface and aggregate microstructure of the concrete specimens by scanning electron microscopy (SEM) method to reveal changes occurred after the cycle of heatingcooling. The results revealed that relative strength of the concrete specimens decreased as the exposure temperature increased and reaches about a quarter of its initial strength at 900°C. Moreover SEM examinations showed that, increasing temperature caused weakening of the adherence of aggregate and cement matrix by the appearance of cracks and micro cracks.

Pull‐out capacity prediction of sustainable cementitious composites with artificial intelligence and statistical methods

“…It can be explained due to the dehydration of the matrix components when the temperature rises from 110 C to 550 C. This deformation causes shrinkage and cracking of the concrete and losing the bond strength. 29,30 FS of the concretes are shown in Figure 3. As in the CS, the FS also decreased with the increase of temperature level.…”

Experimentally evaluation of high-performance concrete mixes used for tunnels and containing silica fume and polypropylene fiber after exposed to high temperatures

“…Another study presented an experimental program undertaken to quantify the effect of elevated temperatures of 60, 75, 100, 200, 400, and 600°C on high-strength concrete cylinders for comparing their performance and residual tensile and compressive strengths of concrete, as well as mass loss values after high temperature were determined [8,10]. Another study on the effect of high temperature on the performance of concrete was implemented by Nesrine Khodja and Hadda Hadjab [11]. They were carried out using two mixtures: normal concrete and HPC with 10% silica fume (SF) replaced by cement weight.…”

The influence of adding alccofine and nano-silica on the behavior of concrete at elevated temperatures

“…The ultrasonic approach is widely used to assess the durability of concrete buildings in place (12,13) . Chemical changes and physical changes in concrete morphology under such scenarios significantly impact its mechanical characteristics (14,15) . Even though the precision of predicting compressive strength via UPV is not high, a relative decrease in UPV, regularly assessed in a concrete specimen exposed to elevated heating, can be used to identify the occurrence of defects in concrete (16,17) .…”