# Engineering Properties of Colorful Mortar with Inorganic Color Paste
## 3 Results and Discussion
(5) Tensile strength  
As shown in Figure 7, the tensile strengths of colorful mortar without color paste (control group) at the ages of 3, 28 and 120 days are 4.38, 5.67 and 6.92 MPa. The tensile strengths of colorful mortar with 5% inorganic color paste at the three ages are 3.96-4.96 MPa, 6.20-7.58 MPa and 8.33-9.17 MPa. The tensile strengths of colorful mortar with 10% inorganic color paste are 3.83-4.08 MPa, 5.80-7.04 MPa and 7.80-8.96 MPa. The tensile strengths of colorful mortar with 15% inorganic color paste at the three ages are 3.42-3.96 MPa, 4.79-6.58 MPa and 7.13-8.21 MPa. The results show that the tensile strengths of various contents and various colors at the age of 120 days are higher than the control group, and the tensile strength of colorful mortar from the age of 28 days to the age of 120 days (excluding various contents of red inorganic color paste and 15% black  
Figure 6: Flexural strength of mortar with different proportions of inorganic color paste. inorganic color paste) is lower than the control group, meaning the mortar has better tensile strength at the age of 28 days. This may because the polyacrylic emulsion can improve the tensile property of mortar. (6) Ultrasonic pulse velocity  
As shown in Table 5 and Figure 8, the ultrasonic pulse velocity of the control group at the age of 3 days is 4037 m/s, at the age of 28 days is 4413 m/s, and the growth of ultrasonic pulse velocity of the control group during the age of 3 to 28 days is about 8.53%. The ultrasonic pulse velocity at the age of 120 days is 4479 m/s, and the growth of ultrasonic pulse velocity of the control group during the age of 28 to 120 days is about 1.49%. When the content of inorganic color paste is 5%, the ultrasonic pulse velocity at the age of 3 days is 3533-3799 m/s, that at the age of 28 days is 3770-4010 m/s, that at the age of 120 days is 3917-4313 m/s, and the growth of ultrasonic pulse velocity during the age of 3 to 28 days is 5.52-11.67%, while that during the age of 28 to 120 days is 2.22-6.74%. When the content of inorganic color paste is 15%, the ultrasonic pulse velocity at the age of 3 days is 3376.67-3632.67 m/s, that at the age of 28 days is 3700-3949 m/s, the growth of ultrasonic pulse velocity during the age of 3 to 28 days is 3.22-8.27%, the ultrasonic pulse velocity at the age of 120 days is 3750-4167 m/s, and the growth of ultrasonic pulse velocity during the age of 28 to 120 days is 2.74-7.49%. The results show that the ultrasonic pulse velocity increases with age, and the ultrasonic pulse velocities of various colors and various contents at various ages are lower than the control group. This may because there are bubbles formed when the polyacrylic emulsion is being mixed with mortar and the air cannot be discharged effectively during compacting, resulting in a lower ultrasonic pulse velocity than the control group. A certain compressive strength can be provided after the polyacrylic emulsion is hardened, and the hydration product cannot effectively fill the pores, so that the ultrasonic pulse velocity is lower than the control group. Figure 7: Tensile strength of mortar with different proportions of inorganic color paste. (7) Surface resistivity  
As shown in Figure 9, the surface resistivities of the control group at different ages (3 days, 28 days and 120 days) are 25, 45 and 99 k\(\Omega\)-cm. When the content of inorganic  
Figure 8: Ultrasonic Pluses Velocity of mortar with different proportions of Inorganic Color Paste.