*3.8. Water Absorption Rate*

As shown in Figure 9, at the age of 28 days, with W/B ratios of 0.4, 0.5, and 0.6, a GGBFS content of 20%, and a waste PE content of 1~4%, the water absorption rates are 5.2~6.1%, 8.7~10.5%, and 13.1~14.2%, respectively. The water absorption rate is increased with an increasing W/B ratio.

**Figure 9.** Water absorption rate of cement mortar with different W/B ratios and waste PE.

At the age of 28 days, with a W/B ratio of 0.5, a GGBFS content of 20%, and different percentages of waste PE added to the cement mortar, the water absorption rates are 8.7%, 9.0%, 9.4%, 9.9%, and 10.5%, respectively. The water absorption rate is increased with the waste PE content because the addition of waste PE induces the balling phenomenon, which increases the internal porosity of the specimen, and the water absorption rate is increased with PE fiber material content.

Pores are formed inside the specimen as the W/B ratio and waste PE content are increased so that the internal porosity of the specimen is increased. The hydration of GGBFS occurs slowly at an earlier age, so the specimen has a higher water absorption rate than the control group; however, under the effect of pozzolanic reaction, the specimen pores are filled up, and the specimen has a better density.

#### *3.9. Resistivity*

As shown in Table 8 and Figure 10, at the age of 28 days, for a W/B ratio of 0.4 and waste PE content of 1%, the resistivity is 26.6 kΩ-cm; for a W/B ratio of 0.5, the resistivity is 25.4 kΩ-cm (reduced by 4.5%); for a W/B ratio of 0.6, the resistivity is 20.9 kΩ-cm, which is reduced by 21.4% in comparison to that for a W/B ratio of 0.4, meaning that the resistivity is obviously decreased as the W/B ratio is increased for a waste PE content of 1%.

For a W/B ratio of 0.5 and a waste PE content of varying percentages, at the age of 3 days, the resistivity is 10~8.1 kΩ-cm, and the resistivity is reduced by 5~20% as the waste PE content is increased. At the age of 28 days, the resistivity of the specimen without waste PE is 26.3 kΩ-cm, and as the waste PE content is increased to 4%, the resistivity is 23.3 kΩ-cm (reduced by 11.4%), meaning that the resistivity is decreased with increasing waste PE content. At the age of 91 days, the resistivity of the control group is 38.9 kΩ-cm; the resistivity of the specimen with a waste PE content of 4% is 33.8 kΩ-cm, and when the PE material content is increased from 0 to 4%, the resistivity is reduced by 13.1%, meaning the specimen structure has a better density at the later age.


**Table 8.** Resistivity of cement mortar with different W/B ratios and waste PE (unit: kΩ-cm).

**Figure 10.** Resistivity of cement mortar with different W/B ratios and waste PE.

When the waste PE content is increased, fiber agglomerates are formed; hence, the resistivity is decreased; at the age of 28 days, the resistivity of various mix proportions is higher than 20 kΩ-cm, showing durability.

#### *3.10. Resistance to Sulfate Attack*

As shown in Figure 11, at the age of 28 days, with W/B ratios of 0.4, 0.5, and 0.6, GGBFS content of 20%, and waste PE content of 1~4%, the weight loss rates are −3.3~3.4%, −6.6~7.1%, and −9.2~10.2%, respectively. When the W/B ratio is increased, the resistance to sulfate attack is degraded, and the weight loss is increased. When the W/B ratio is low, the internal porosity of the specimen is reduced, the specimen is denser, and the resistance to sulfate attack is better.

At the age of 28 days, when the W/B ratio is 0.5, the weight loss rates for cement mortar specimens with a waste PE content of 0%, 1%, 2%, 3%, and 4% are −6.6%, −6.7%, −6.9%, −7.1%, and −7.1%, respectively, after five cycles, meaning that when the waste PE content is increased, the weight loss rate is increased, and the resistance to sulfate attack is degraded. This phenomenon was observed because the internal porosity of the material increases with the waste PE content, and the sulfate solution more easily erodes the specimen. When the W/B ratio and the waste PE content are increased, the internal porosity of the specimen and the weight loss rate are increased.

**Figure 11.** Resistance to sulfate attack of cement mortar with different W/B ratios and waste PE.
