1 Introduction
2 Experimental Program
2.1 Mixture Proportions and Materials
Specimen | w/c (%) | s/a (%) | Water (kg/m3) | Unit content (kg/m3) | Aggregate type | |||
---|---|---|---|---|---|---|---|---|
Cement | Fine aggregate | Coarse aggregate | Fine aggregate | Coarse aggregate | ||||
65-NC | 65 | 47.0 | 175 | 270 | 834 | 957 | N | N |
65-RC | 942 | R | ||||||
45-NC | 45 | 43.1 | 175 | 389 | 724 | 972 | N | |
45-RC | 957 | R |
Specimens | Recycled aggregate | Natural aggregate | |
---|---|---|---|
Coarse aggregate | Coarse aggregate | Fine aggregate | |
Density SSD (g/cm3) | 2.56 | 2.60 | 2.56 |
Dry density (g/cm3) | 2.50 | 2.58 | 2.51 |
Absorption ratio (%) | 2.50 | 1.07 | 2.25 |
Fineness modulus | 6.69 | 6.54 | 2.93 |
2.2 Shape and Kind of Specimens
2.3 Testing Methods
3 Results and Analysis
3.1 Mechanical Properties of Concrete
Specimen | Items | 7 days | 14 days | 28 days |
---|---|---|---|---|
65-NC |
f
c
(MPa) | 26.3 | 32.5 | 38.4 |
f
st
(MPa) | 2.3 | 2.6 | 2.9 | |
E
c
(GPa) | 22.9 | 25.5 | 27.7 | |
65-RC |
f
c
(MPa) | 22.0 | 28.6 | 30.3 |
f
st
(MPa) | 2.1 | 2.3 | 2.6 | |
E
c
(GPa) | 20.9 | 23.9 | 24.6 | |
45-NC |
f
c
(MPa) | 39.4 | 46.1 | 49.9 |
f
st
(MPa) | 2.8 | 3.1 | 3.4 | |
E
c
(GPa) | 28.0 | 30.3 | 31.5 | |
45-RC |
f
c
(MPa) | 33.5 | 38.7 | 40.0 |
f
st
(MPa) | 2.6 | 2.8 | 3.1 | |
E
c
(GPa) | 25.8 | 27.8 | 28.3 |
3.2 Drying Shrinkage
3.3 Uniaxial Restrained Shrinkage Cracking Test
3.3.1 Cracking Age
Specimen | Cracking age | Average value (cracking age) |
---|---|---|
URSC 65-NC-1 | 37 days | 34.3 days |
URSC 65-NC-2 | 35 days | |
URSC 65-NC-3 | 31 days | |
URSC 65-RC-1 | 33 days | 32.3 days |
URSC 65-RC-2 | 31 days | |
URSC 65-RC-3 | 33 days | |
URSC 45-NC-1 | 30 days | 30.0 days |
URSC 45-NC-2 | 29 days | |
URSC 45-NC-3 | 31 days | |
URSC 45-RC-1 | 32 days | 30.3 days |
URSC 45-RC-2 | 29 days | |
URSC 45-RC-3 | 30 days |