**Table 1.**

*The chemical and physical properties of cement and silica fume [18].*

**Figure 1.** *Particle size distributions of silica fume [18].*

taken from the region of Bou Sâada (250 km east of Algiers). The sieve analysis is performed according to the European standard NF EN 933-1. The mineralogical composition determined by X-ray diffraction shows that the siliceous sand is more than 95% of quartz and calcite traces.

The coarse fraction of aggregate is gravel (G1) of size 3/8 mm and gravel (G2) of size 8/15 mm. The adjuvant used is a super plasticizer which is highly water reducing (Medaplast SP40). It is a solution of pH = 8.2 and a density of 1.22, with 40% of solids. Its normal use scale is fixed by the manufacturer's recommendation which is between 0.6 and 2.5% of the cement weight. The tap water used all through the study from mixing was taken from the laboratory of civil engineering.

### **3.2 Mixture design**

Fresh concrete mixes were prepared in a modified laboratory mixer; the mixing procedure is explained in **Table 2**. The concrete specimens were preserved in their molds in a wet place at a temperature of 20°C and 95% relative humidity (RH) during 24 h. After demolding, they were immersed in water at 20°C until the age of testing. The physical and mechanical characteristics of the concretes with and without the addition of silica fume have been compared. The silica fume is added at a dosage of 5% cement weight and the super plasticizer at 2 and 2.5%, respectively. The final compositions of high-performance concrete (HPC), after optimization, are reported in **Table 3** [19, 22].

The following acronyms will be used henceforth:

CR2.5: Concrete without silica fume and 2.5% (by weight of cement) of the chemical admixture.

HPC2.5: Concrete dosed at 5% of silica fume and 2.5% of the chemical admixture. HPC2: Concrete dosed at 5% of silica fume and 2% of the chemical admixture.


**113**

*Mechanical Behavior of High-Performance Concrete under Thermal Effect*

After 28 days, specimens with dimensions (100 mm × 100 mm × 100 mm3

**) Cement Sand Gravel (3/8, 8/15) Water Additions**

CR2.5 400 662 1090 220 — 2.5 HPC2.5 444 645 1042 119 5 2.5 HPC2 444 662 1042 122 5 2

dried in an oven (at 100 °C), until stabilization of their mass. All specimens are subjected to high temperatures, 200, 400, 600, and 900°C, according to the timetemperature schedule of ASTM E 119-00 [39]. After cooling, they were subjected

The slump values were obtained for all three mixtures according to the NF EN 12390-4 and EN 12390-5 [40, 41]. The axial compressive strength was tested at 28 days according to NF EN 12390-4 [40] for the concrete at 20°C that was not

The protocol of porosity accessible to water conforms the recommendations of AFREM group [42]. The open porosity allows us to appreciate the evolution of hydration and structuration of hydrated products; this is a key for identification of the most sustainable concrete [43]. The test pieces for testing of water porosity are dried in an oven at a temperature of 100°C to constant weight and then returned to

The porosity test is carried out on test pieces of dimensions 10 × 10 × 10 cm3

• Dry in an oven at 105°C the sample for at least 24 h until obtaining a constant

• Heat to boil for 5 h, and then weigh the sample in air (i.e., the weight is denoted

C − A

Phase compositions of these concretes were investigated on the fine powders using X-ray diffraction method. The powder samples of concrete heat-treated aggregates at 20, 600, and 900°C were collected after abrasion. X-ray diffraction analysis was performed on an X-ray diffractometer (X'Pert) coupled to a computer system. The essential purpose of this analysis is to identify the different phases of

Gravimetric and differential thermal analyses (ATG and ATD) make it possible to quantify portlandite; these techniques are used to characterize degradations.

<sup>C</sup> <sup>−</sup> <sup>D</sup><sup>×</sup> <sup>100</sup> (1)

P (%) <sup>=</sup> \_

) are

**Silica fume (%) Super plasticizer (%)**

, by

*DOI: http://dx.doi.org/10.5772/intechopen.89916*

*Compositions of concrete with and without silica fume [18].*

to compression tests.

**Mix (kg/m3**

**Table 3.**

subjected to high temperatures.

room temperature in a desiccator.

mass. This mass is denoted as "A."

• Immerse the sample in water for 24 h.

The porosity was calculated by the formula:

• Then hydrostatic weigh (the weight is denoted as "D").

applying the following steps:

as "C").

crystal present in a sample.

**Table 2.**

*Mixing procedure [18].*


#### **Table 3.**

*Compressive Strength of Concrete*

than 95% of quartz and calcite traces.

*Particle size distributions of silica fume [18].*

**3.2 Mixture design**

**Figure 1.**

are reported in **Table 3** [19, 22].

chemical admixture.

The following acronyms will be used henceforth:

60 Mixing of aggregates, silica fume, cement

30 Addition of the remaining super plasticizer

**Time,s Mixing procedure**

180 Mixing

60 Mixing

taken from the region of Bou Sâada (250 km east of Algiers). The sieve analysis is performed according to the European standard NF EN 933-1. The mineralogical composition determined by X-ray diffraction shows that the siliceous sand is more

study from mixing was taken from the laboratory of civil engineering.

The coarse fraction of aggregate is gravel (G1) of size 3/8 mm and gravel (G2) of size 8/15 mm. The adjuvant used is a super plasticizer which is highly water reducing (Medaplast SP40). It is a solution of pH = 8.2 and a density of 1.22, with 40% of solids. Its normal use scale is fixed by the manufacturer's recommendation which is between 0.6 and 2.5% of the cement weight. The tap water used all through the

Fresh concrete mixes were prepared in a modified laboratory mixer; the mixing procedure is explained in **Table 2**. The concrete specimens were preserved in their molds in a wet place at a temperature of 20°C and 95% relative humidity (RH) during 24 h. After demolding, they were immersed in water at 20°C until the age of testing. The physical and mechanical characteristics of the concretes with and without the addition of silica fume have been compared. The silica fume is added at a dosage of 5% cement weight and the super plasticizer at 2 and 2.5%, respectively. The final compositions of high-performance concrete (HPC), after optimization,

CR2.5: Concrete without silica fume and 2.5% (by weight of cement) of the

30 Addition 100% of water and a third of the volume of super plasticizer

HPC2.5: Concrete dosed at 5% of silica fume and 2.5% of the chemical admixture. HPC2: Concrete dosed at 5% of silica fume and 2% of the chemical admixture.

**112**

**Table 2.**

*Mixing procedure [18].*

*Compositions of concrete with and without silica fume [18].*

After 28 days, specimens with dimensions (100 mm × 100 mm × 100 mm3 ) are dried in an oven (at 100 °C), until stabilization of their mass. All specimens are subjected to high temperatures, 200, 400, 600, and 900°C, according to the timetemperature schedule of ASTM E 119-00 [39]. After cooling, they were subjected to compression tests.

The slump values were obtained for all three mixtures according to the NF EN 12390-4 and EN 12390-5 [40, 41]. The axial compressive strength was tested at 28 days according to NF EN 12390-4 [40] for the concrete at 20°C that was not subjected to high temperatures.

The protocol of porosity accessible to water conforms the recommendations of AFREM group [42]. The open porosity allows us to appreciate the evolution of hydration and structuration of hydrated products; this is a key for identification of the most sustainable concrete [43]. The test pieces for testing of water porosity are dried in an oven at a temperature of 100°C to constant weight and then returned to room temperature in a desiccator.

The porosity test is carried out on test pieces of dimensions 10 × 10 × 10 cm3 , by applying the following steps:


The porosity was calculated by the formula:

$$
\begin{aligned}
\text{by the formula:}\\\\
\text{P (\%)} &= \frac{\text{C} - \text{A}}{\text{C} - \text{D}} \times 100\end{aligned}
\tag{1}
$$

Phase compositions of these concretes were investigated on the fine powders using X-ray diffraction method. The powder samples of concrete heat-treated aggregates at 20, 600, and 900°C were collected after abrasion. X-ray diffraction analysis was performed on an X-ray diffractometer (X'Pert) coupled to a computer system. The essential purpose of this analysis is to identify the different phases of crystal present in a sample.

Gravimetric and differential thermal analyses (ATG and ATD) make it possible to quantify portlandite; these techniques are used to characterize degradations.
