This study investigated the effect of elevated temperature on the mechanical and physical properties of concrete specimens obtained by substituting cement with finely ground pumice (FGP) at proportions of 5%, 10%, 15% and 20% by weight. To determine the effect of silica fume (SF) additive on the mechanical and physical properties of concrete containing FGP, SF has been added to all series except for the control specimen, which contained 10% cement by weight instead. The specimens were heated in an electric furnace up to 400, 600 and 800 1C and kept at these temperatures for one hour. After the specimens were cooled in the furnace, ultrasonic pulse velocity (UPV), compressive strength and weight loss values were determined. The results demonstrated that adding the mineral admixtures to concrete decreased both unit weight and compressive strength. Additionally, elevating the temperature above 600 1C affected the compressive strength such that the weight loss of concrete was more pronounced for concrete mixtures containing both FGP and SF. These results were also supported by scanning electron microscope (SEM) studies.

In this study, corrosion behavior of six different dual-phase (DP) steels with varying morphologies and martensite content has been examined in comparison to ferrite-pearlite steel in concrete. Intercritical annealing and intermediate quenching heat treatments have been applied to the reinforcing steel in order to obtain DP steels with different morphologies and content of martensite. Corrosion experiments were conducted in two stages. In the first stage, the corrosion potential of steels embedded in concrete was measured every day for a period of 30 days in accordance with ASTM C 876 standard. In the second stage, anodic and cathodic polarization values of these steels were obtained and then the corrosion currents were determined with the aid of cathodic polarization curves. It has been observed that both the amount of martensite and the morphology of the phase constituents have definite effect on the corrosion behavior of DP steel embedded in concrete. As a result of this study, it is found that corrosion rate of dual-phase steel has increased with increase amount of martensite.

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h i g h l i g h t s We investigated the performance of the mortar with marble dust and glass fiber exposed to high temperature. This article applied the Taguchi method and ANOVA analysis. The compressive strength increased with increase of marble dust percentage. The most important parameter on the responses was found as temperature degree.

This paper investigated the usability of marble dust and glass fiber against the harmful effects of freeze-thaw (FT) cycles on cement mortars as experimentally and statistically. To this end, the cement mortar specimens containing marble dust (0%, 20%, 40% and 50% by volume) and glass fiber (0 kg/m 3 , 0.25 kg/m 3 , 0.50 kg/m 3 , 0.75 kg/m 3) were prepared. The compressive and flexural strengths of the specimens were determined after being exposed to FT cycles. In order to reduce the numbers of experiments, an L 16 (4 2 Â 2 1) Taguchi orthogonal array was adopted to the study. Amounts of glass fiber, percentages of marble dust and cycles of freeze-thaw, were changed to explore their effects on the compressive and flexural strengths of the mortar specimens. Statistically effects of the factors were also determined by using analysis of variance (ANOVA) method. Finally, experimental findings were compared with statistical results and a good agreement between them was achieved.