PSI - Issue 67

73 13

Dan Huang et al. / Procedia Structural Integrity 67 (2025) 61–79 Huang, D., Velay-Lizancos, M., Olek, J./ Structural Integrity Procedia 00 (2024) 000–000

The quantitative data for initial and secondary absorption values of the OPC concretes with and without the addition of nanoparticles cured at different temperatures are shown in Fig. 10. When comparing the reference concretes (OPC1 vs OPC2), the OPC1 concrete exhibits a lower initial and secondary absorption. This is expected as OPC1 concrete (with lower w/cm) intrinsically contains a lower amount of capillary porosity compared to OPC2. Another observation is that both the initial and secondary absorptions of concrete cured at a low temperature (4°C) are slightly higher than that of concrete cured at room temperature (23°C). This, again, underscores the influence of curing temperature on the properties and microstructure of concretes.

OPC1-0nT

OPC1-0.5nT

OPC2-0nS OPC2-12nS OPC2-8nS OPC2-4nS

3

3

(a) Initial absorption, mm 3 /mm 2 0 1 2 23°C

(b) Initial absorption, mm 3 /mm 2 0 1 2 23°C

4°C

4°C

Curing Temperature

Curing Temperature

OPC1-0nT

OPC1-0.5nT

OPC2-0nS OPC2-12nS OPC2-8nS OPC2-4nS

0 1 2 3 4 5 6

0 1 2 3 4 5 6

(c)

(d)

mm 3 /mm 2

mm 3 /mm 2

Secondary absorption,

Secondary absorption,

23°C

4°C

23°C

4°C

Curing Temperature

Curing Temperature

Fig. 10. The initial and secondary absorption values of OPC concrete with and without the addition of nano-TiO 2 (a, c) and (b) nano-silica (b, d) cured at different temperatures. (adapted from (Dan Huang, 2022))

As shown in Fig. 10, the addition of nanoparticles reduced both the initial and secondary absorptions, irrespectively of the type of nanoparticles used and the curing temperature. This implies that both types of nanoparticles likely reduced the capillary porosity. Moreover, such porosity reduction effect is more pronounced in specimens containing nano-silica, compared to nano-TiO 2 , especially at low curing temperature. Table 4 provides a summary of both the initial and secondary rates of absorption, as well as the R 2 values for the lines fitted to absorption data shown in Fig. 8 and Fig. 9 for various concrete samples. These parameters are essential components of the report generated from the water absorption test, as stipulated by ASTM C1585-20 [34].