PSI - Issue 67

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

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conducted). After the corresponding curing period was finished, concrete samples were subjected to various testing and measurement procedures described in the following section.

Table 3. The mixture proportions of plain and nanomodified OPC concretes.

Content (lb/yd 3 )/(kg/m 3 )

Nano-silica, (oz/cwt* cem.) /ml/100kg cem.

Mix No.

Coarse aggregate

Nano-TiO 2 , % wt. of cem.

Water

Cement

Fine aggregate

OPC1-0nT w/c=0.44 OPC1-0.5nT w/c=0.44 OPC1-1nT w/c=0.44 OPC2-0nS w/c=0.45

248/147

564/335

1350/801

1700/1009

0

/

248/147

564/335

1350/801

1700/1009

0.5

/

248/147

564/335

1350/801

1700/1009

1

/

254/151

564/335

1345/798

1700/1009

/

0

12 (8 LFA + 4 IC)/750 (500 LFA+ 250 IC)

OPC2-12nS w/c=0.45

254/151

564/335

1345/798

1700/1009

/

OPC2-8nS w/c=0.45 OPC2-4nS w/c=0.45

8 LFA/500 LFA

254/151

564/335

1345/798

1700/1009

/

254/151

564/335

1345/798

1700/1009

/

4 IC/250 IC

*oz/cwt= oz/100 lb of cement

3. Testing methods 3.1. Compressive strength

Concrete cylinders were cast to evaluate the effect of both nano-TiO 2 and nano-silica on the 28-day compressive strength of OPC concrete. For each concrete type listed in Table 3, six 4 in. by 8 in. (100 mm x 200 mm) cylinders were fabricated, with three of them subjected to lime-saturated water with a curing temperature of 23°C, while the remaining three were cured at a low temperature of 4°C. The compressive strength of the concrete was determined in accordance with ASTM C39-20 (ASTM C39/C39M-20, 2003) after a curing period of 28 days. 3.2. Flexural strength To explore the effects of various nanoparticles on the flexural strength of concrete, 12 prism concrete samples (measuring 3 in. x 4 in. x 16 in. (76 mm x 100 mm x 406 mm)) were prepared for each concrete type. Consistent with the curing protocol outlined earlier, the concrete prisms were split into two groups, each group subjected to distinct curing temperatures (standard 23°C and low 4°C). Following this, the flexural strength of the concrete was evaluated according to ASTM C78-18 (C78-18, 2010) test method after both 7 and 28 days of curing.