**3.1 Materials and methods**

*Compressive Strength of Concrete*

mix for every temperature and duration of high temperature exposure. An easy way to comply with the conference paper formatting requirements is to use this docu-

According to Santosh Kumar et al. [33], the materials like pozzalonas may be natural and artificial like industrial wastes or by-products which require less energy to make fine particles. These materials exhibit cementitious properties and combine

Gowri et al. presents the results of experimental studies conducted on performance of High Volumes of Slag Concrete (HVSC) exposed to elevated temperatures up to 600°C. In HVSC, 50% of cement is replaced with Ground Granulated Blast Furnace Slag (GGBS). In this experimental studies, HVSC of 100 mm cubes are cast and tested for various water/binder ratios ranging from 0.55 to 0.27. The specimens are exposed to elevated temperatures of 200°C, 400°C and 600°C for 4, 8, 12 hours. Result of compressive strengths and weights of cubes after expose to high temperature are estimated. Percentage loss in compressive strengths and weights are also evaluated. The results illustrate that the loss in compressive strength and weights are more for higher temperatures for longer duration for higher water/binder ratios [35]. According to Jawed et al., percentage loss of compressive strength is higher with an increase amount of fly ash in concrete samples, i.e., for 20% fly ash concrete. This is due to high impermeability and moisture gained in longer curing period

In 2004, Yüzer et al. carried out a study on the effects of fire, and extinguishing on the properties of concrete, mortars with and without silica fume were exposed to different temperatures, such as 100, 200, 300, 600, 900, and 1200°C and cooled slowly in the air and fast in water in two groups. Flexural and compressive strength tests were performed on the samples which were cooled up to room temperature, and changes in compressive strength in color were determined by Munsell color system. High temperature has caused damages to decrease in mechanical strengths at 600°C. Researchers observed that the changes in color hue component and the compressive strength have similarities. Test results show that residual color changes in mortar can give an idea about the effect of high temperatures on mechanical properties of mortar during a fire [37]. Ahmad's research includes an experimental investigation to study the effect of high temperatures on the mechanical properties of concrete containing admixtures. A comparative study was conducted on concrete mixes, reference mix without an additive, and that with an admixture. Concrete was exposed to three levels of high temperatures (200, 400, 600°C), for duration of 1 h, without any imposed load during the heating. Super plasticizer, plasticizer, retarder, water-reducing admixture, an accelerator, and an air entraining admixture, five types of admixtures, were used. Mechanical properties of concrete were studied at different high temperatures, including compressive strength, splitting tensile strength, modulus of elasticity, and ultimate strain. Test results showed a reduction in the studied properties by different rates for different additives, and for each temperature, the decrease was very limited at a temperature up to 200°C but was clear at 400–600°C [38].

ment as a template and simply type your text into it [32].

with calcium hydroxide producing cementitious material [34].

resulting in high pore pressure but low initial strength gain [36].

**3. Tebbal et al.'s research on the effect of temperature on** 

This study examines the effect of the additions of silica fume and super plasticizer on the mechanical performance of high-performance concretes at high temperatures. The tested concretes are formulated with 5% silica fume and two dosages of super plasticizers in the ratio of (2%, 2.5%) the weight of cement after having been exposed to four maximum temperatures, 200, 400, 600, and 900°C, without any imposed

**high-performance concrete**

**110**

The portland cement-type CEM II/A 42.5 from Hammam Dalâa local factory was used in this experimental study. The used cement type has an absolute density, consistency, and fineness values of 3.1 g/cm3 , 28%, and 4000 cm2 /g, respectively. The chemical composition of the cement is shown in **Table 1**.

The silica fume is obtained from GRANITEX in Algeria region. It results from melting the silicon and ferrosilicon. The reduction of high-purity quartz to silicon at temperatures up to 2000°C produces SiO2 vapors, which oxidize and condense in the low-temperature zone to tiny particles consisting of noncrystalline silica [39]. The physical properties and particle size by laser granulometer (Mastersizer 2000) of silica fume are shown in **Table 1** and **Figure 1**.

The natural fine aggregates used were dune sand with particles ranging from 0.08 to 5 mm in size, with a fineness modulus, Mf, of 2.44. This natural sand was

