# Temperature Impact on Engineered Cementitious Composite Containing Basalt Fibers
## 3 Result and Discussions
### Results of the Compressive Strength Test  
Compressive strength is the most important mechanical characteristic of construction materials due to the fact of its significant role as the compliance criteria in standards and specifications. The compressive strength of the cubic samples of 50 mm in dimension made according to the ASTM C109/C109 M-08 standard was first tested after 28 days of curing at room temperature without exposure to high temperatures. The compressive strength of the samples in fiber-reinforced and fiber-free specimens was 41.7 MPa and 43.3 MPa, respectively. The results of the compressive strength tests are illustrated in Figure 4 for reference mixes and fiber-reinforced ECC. The results in each point were obtained from the average of triplicate specimens.  
Figure 3: Testing machines used for (**a**) flexural strength and (**b**) compressive strength.  
It was observed that the temperature increase in BF-reinforced ECC up to 100 \({}^{\circ}\)C increased the compressive strength, while exposure to a higher temperature range (i.e., 100-400 \({}^{\circ}\)C) resulted in approximately 44% of its decrease. The maximum growth in the compressive strength of BF-ECC was achieved at 100 \({}^{\circ}\)C. With the passage of time, cement hydration increased. The encapsulated micro- or macro-size water droplets within the concrete composition were gradually released by temperature increases from room temperature to 100 \({}^{\circ}\)C. The evaporation of the encapsulated water improved the curing efficiency by facilitating the hydration of the cementitious system and positively influenced the strength growth rate of the concrete. The pattern of change in compressive strength of the BF-ECC was similar to the one for the reference state except in the range of 100-200 \({}^{\circ}\)C where there existed small increases in compressive strength in the reference ECC, while there was a decrement in the BF-ECC. However, the range of variation in the R-ECC was much smoother compared to the BF-ECC due to the fact of exposure to an elevated temperature. Reduction in the compressive strength of the ECC under an elevated temperature up to 400 \({}^{\circ}\)C may be due to the fact that this concrete completely lost its water up to 400 \({}^{\circ}\)C. Up to 100 \({}^{\circ}\)C, the hydration of waterless cement aggregates improved due to the fact of its internal autoclave conditions. This is especially the case with high-strength concrete. The above is true because its low permeability had a great effect on moisture transfer. In the temperatures above 350 \({}^{\circ}\)C, calcium hydroxide decomposed into either lime and water, or C-S-H due to the pozzolanic reaction accelerated at high temperatures, where the decomposition of hydroxide calcium had a minor effect on the reduction in resistance.  
The reduction in the compressive strength by the addition of BF is in agreement with the experimental result observations reported by other authors [81; 82; 83]. This decrease was mainly caused by compactness reduction due to the introduction of voids into the ECC matrix during the incorporation of the BFs into the composite. However, the observation during compressive tests of BF-ECC indicated a more ductile failure absorbing a larger amount of plastic energy under compressive loads compared to the fiber-free control mixture.