Methodologies for Estimating Properties of Concrete Containing Recycled Aggregates: Analyses of Experimental Research - Recycled Aggregate in Concrete - page 364

Fig. 6.13 Ratio between
concrete splitting tensile
strengths versus ratio
between densities of
aggregates in mix (top), water
absorptions of aggregates in
mix (middle) and 7-day
compressive strengths
(bottom) of concrete

1.00

y = -3.0904x + 1
R 2 = 0.7189

0.95

Evangelista
Figueiredo
Gomes
Matias
Rocha & Resende
Gomes (ceramics)

0.90

0.85

0.80

0.75

0.00 0.01 0.02 0.03 0.04 0.05 0.06

1-D RAC /D RC

1.05

y = -0.0565x + 1
R 2 = 0.6183

1.00

0.95

Evangelista
Gomes
Matias
Rocha & Resende
Gomes (ceramics)
Gomes (mixed)

0.90

0.85

0.80

0.75

0.00 0.50 1.00 1.50 2.00 2.50 3.00

wa RAC /wa RC -1

1.00

0.96

0.92

y = -1.4847x + 1
R 2 = 0.8039

0.88

Evangelista
Figueiredo
Matias
Gomes (ceramics)

0.84

0.80

0.76

0 0.05 0.1 0.15

1-f c7RAC /f c7RC

Once again, the lower mechanical properties of the recycled aggregates when
compared with the natural ones lead to a fall in the splitting tensile strength of the
former as the replacement rate increases. The slope of the correlation lines, even
though lower than for the modulus of elasticity, is generally higher than for the
compressive strength, which somehow contradicts the existing literature as pre-
sented in Chap. 5 , which states that the concrete mixes that use recycled aggre-
gates are slightly less sensitive to the inclusion of these aggregates for tensile
strength than for compressive strength.