Understanding defects, testing and inspection - Concrete Repair - page 6

Table 1.2 Variation between core and cube strength in concrete (Concrete Society, 2004)
Cement Mixes Element 28 Days 42 Days 84 Days 365 Days

Min Max Min Max Min Max Min Max

PC Lower Strength Mixes Block 0.75 0.95 0.80 0.95 0.85 1.05 0.95 1.10

Slab 1.00 1.25 1.05 1.35 1.05 1.50 1.15 1.60

Wall 0.85 0.95 0.85 1.00 0.85 1.05 0.90 1.10

Higher Strength Mixes Block 0.60 0.70 0.70 0.75 0.70 0.80 0.75 0.90

Slab 0.85 1.00 0.95 1.10 0.95 1.15 1.05 1.25

Wall 0.85 0.95 0.80 0.95 0.85 1.00 0.95 1.05

P/FA-B Lower Strength Mixes Block 0.85 1.10 0.85 1.20 0.95 1.35 1.45 1.65

Slab 0.80 1.20 0.90 1.30 1.00 1.50 1.65 2.15

Wall 0.80 1.05 0.85 1.10 1.05 1.30 1.50 1.60

Higher Strength Mixes Block 0.75 1.00 0.80 1.00 0.95 1.05 1.00 1.35

Slab 0.75 0.95 1.00 1.15 1.15 1.25 1.20 1.70

Wall 0.80 1.00 0.90 1.05 1.05 1.25 1.35 1.40

P/B Lower Strength Mixes Block 0.70 1.10 0.85 1.10 1.00 1.20 1.15 1.35

Slab 0.65 1.15 0.85 1.30 1.20 1.40 1.35 1.70

Wall 0.70 1.00 0.85 1.15 1.05 1.25 1.15 1.35

Higher Strength Mixes Block 0.80 1.05 0.95 1.20 0.90 1.25 1.00 1.55

Slab 0.90 1.05 1.05 1.30 1.20 1.30 1.30 1.80

Wall 0.70 1.00 0.85 1.10 1.00 1.20 1.05 1.25

PLC Lower Strength Mixes Block 0.80 0.95 0.85 1.00 0.95 1.10 1.00 1.15

Slab 0.95 1.05 1.05 1.20 1.15 1.35 1.20 1.45

Wall 0.85 1.00 0.90 1.05 0.95 1.00 1.10 1.20

Higher Strength Mixes Block 0.60 0.80 0.70 0.90 0.70 1.00 0.80 0.95

Slab 0.80 0.90 0.95 1.00 1.00 1.05 1.05 1.20

Wall 0.80 0.95 0.90 1.00 0.90 1.05 1.00 1.15