## 4 Results and Discussion  
### Modulus of Elasticity  
The modulus of elasticity is a material constant determined based on the relationship between stress and strain. According to Hook's law, linear elastic material maintains a constant relationship between stress and strain. Strictly speaking, the elastic modulus section means only the linear section of the stress-strain curve. Hence, the secant modulus of elasticity is applied when the linear section of the stress-strain curve is not straight, such as in the stress-strain relationship of concrete. There are other ways to determine the modulus of elasticity, such as the chord modulus of elasticity and tangent modulus of elasticity, but these do not apply to concrete [30]. The modulus of elasticity is one of the major criteria used to evaluate the deformation characteristics of a structure when a load is applied to structural members. If damaged Portland cement concrete is repaired with an EP polymer concrete mixture, a mismatch in the modulus of elasticity for the two materials will reduce the load-bearing capacity of the combined system [20]. In addition, matching the elastic modulus of the material used for the existing substrate and elastic modulus of the repair mixture is very important in terms of shrinkage and permeability [31]. The stress-strain relationships determined by the compression test in the present study are shown in Figure 6. In this figure, the secant modulus of elasticity was determined from the slope formed by the coordinate origin and point corresponding to 40% of the ultimate stress; the result is shown in Figure 7. The modulus of elasticity ranged from \(25.2\times 10^{3}\) to \(27.2\times 10^{3}\) MPa with the AAMT hardener and from \(24.7\times 10^{3}\) to \(27.1\times 10^{3}\) MPa with the CAMT hardener. From these  
Figure 4: Test setup for measuring drying shrinkage. Figure 5: Test setup for measuring thermal expansion. results, it was determined that the moduli of elasticity for the two types of curing agent were similar. By filler type, the order from highest to lowest elastic modulus was SF, GCC, BFS, and FA. This order was the same for both types of hardeners. There was a minor difference between the elastic moduli of the two hardener types. The cause for this minor difference is likely related to the mode of particle size employed in this study. To determine the exact cause of this difference, additional research is required. Figure 6: Compressive stress and strain curves by hardener and filler type: (**a**) AAMT hardener and (**b**) CAMT hardener. Figure 7: Elastic moduli by hardener and filler type. According to previous studies on the moduli of elasticity of EP polymer concrete mixtures, [PERSON] et al. [5] reported levels ranging from 9.5 to 11 GPa, [PERSON] et al. [20] showed 13.2 GPa, [PERSON] et al. [31] demonstrated 0.5 to 20 GPa, and [PERSON] et al. [32] found 8 to 18 GPa. These moduli of elasticity were affected by the type of EP, its contents, the properties of the aggregate, test method employed, temperature, and specimen size. Also, it was determined that the elastic modulus of EP concrete was significantly smaller than the elastic modulus of Portland cement concrete (i.e., 20 to 40 GPa) [6; 31]. This low elastic modulus is not disadvantageous in terms of compatibility with Portland cement concrete when the modulus of elasticity of Portland cement concrete is considered [20]. The compressive strengths are shown in Table 8, as determined when failure stresses in the stress-strain curves shown in Figure 6 were regarded as compressive strengths. These compressive strengths were developed at the age of 7 days. By type of hardener, the compressive strengths of the AAMT hardener ranged from 95.5 to 108.6 MPa, and that of the CAMT hardener ranged from 95.8 to 103.8 MPa. From these results, it was determined that there was no significant difference between the two hardeners. For compressive strength by filler type, the order of strength development from highest to lowest was SF, GCC, BFS, and FA.