1 Introduction
2 Experimental Program
2.1 Specimen Design
2.1.1 Pull-out Specimens
2.1.2 Splice Specimens
2.2 Materials
Bar no. | Modulus of elasticity (MPa) | Yielding strength (MPa) | Elongation (mm/mm) |
---|---|---|---|
13 | 196,600 | 485 | 0.0092 |
19 | 206,250 | 580 | 0.0085 |
2.3 Mixture Proportions
Mix | Water (kg/m3) | Cement (kg/m3) | Fly ash (kg/m3) | Fine aggregate (kg/m3) | Coarse aggregate (kg/m3) | AEA (l/m3) | HRWR (l/m3) |
---|---|---|---|---|---|---|---|
NCC | 165 | 445 | – | 691 | 955 | 0.33 | 1.04 |
NSCC | 165 | 445 | – | 856 | 790 | 0.33 | 1.38 |
HCC | 150 | 500 | 125 | 619 | 854 | 0.40 | 1.55 |
HSCC | 150 | 500 | 125 | 767 | 707 | 0.31 | 2.23 |
2.4 Fabrication and Curing of Test Specimens
2.5 Fresh and Hardened Properties
Property | NCC | NSCC | HCC | HSCC |
---|---|---|---|---|
Slump (mm) | 203 | – | 51 | – |
Slump flow (mm) | – | 610 | – | 597 |
J-Ring (mm) | – | 527 | – | 546 |
Air content (%) | 6 | 6 | 2.5 | 3 |
Unit weight (kg/m3) | 2240 | 2330 | 2440 | 2400 |
Split cylinder strength (MPa)a | 3.0 | 3.6 | 3.9 | 3.9 |
Flexural strength (MPa)b | 3.4 | 3.4 | 4.8 | 3.7 |
Compressive strength (MPa)a | 39.4 | 47.2 | 66.4 | 67.2 |
3 Test Setup and Procedure
3.1 Pull-out Test
3.2 Splice Specimen Test
4 Test Results and Discussions
4.1 Pull-out Tests
Section | \( {\text{f}}_{\text{c}}^{ '} \) (MPa) | P (kN) | \( {{\upmu}} \) (MPa)a | \( \frac{\text{P}}{{\root{{}} \of {{\frac{{{\text{f}}_{\text{c(test)}}^{ '} }}{{{\text{f}}_{\text{c(design)}}^{ '} }}}}}} \) (kN) | Pave (kN) | COV (%)b | \( \frac{\text{P}}{{\root{ 4} \of {{\frac{{{\text{f}}_{\text{c(test)}}^{ '} }}{{{\text{f}}_{\text{c(design)}}^{ '} }}}}}} \) (kN) | Pave (kN) | COV (%)b |
---|---|---|---|---|---|---|---|---|---|
NCC | |||||||||
13-1 | 39.9 | 55.2 | 21.0 | 56.5 | 55.6 | 3.5 | 55.7 | 54.7 | 3.5 |
13-2 | 55.5 | 21.2 | 56.9 | 56.0 | |||||
13-3 | 52.0 | 19.8 | 53.3 | 52.5 | |||||
19-1 | 134.4 | 25.2 | 137.6 | 136.1 | 1.1 | 135.6 | 134.1 | 1.1 | |
19-2 | 132.9 | 24.9 | 136.1 | 134.1 | |||||
19-3 | 131.4 | 24.6 | 134.6 | 132.6 | |||||
NSCC | |||||||||
13-1 | 47.2 | 69.0 | 26.3 | 64.6 | 63.8 | 1.8 | 66.8 | 66.0 | 1.9 |
13-2 | 66.7 | 25.4 | 62.5 | 64.5 | |||||
13-3 | 68.8 | 26.2 | 64.4 | 66.6 | |||||
19-1 | 161.9 | 30.3 | 151.6 | 151.1 | 2.9 | 156.7 | 156.1 | 2.9 | |
19-2 | 156.5 | 29.3 | 146.6 | 151.4 | |||||
19-3 | 165.7 | 31.0 | 155.2 | 160.3 | |||||
HCC | |||||||||
13-1 | 66.4 | 83.0 | 31.6 | 84.6 | 86.4 | 5.2 | 73.7 | 75.3 | 5.2 |
13-2 | 81.6 | 31.1 | 83.1 | 72.5 | |||||
13-3 | 89.8 | 34.2 | 91.5 | 79.8 | |||||
19-1 | 194.2 | 36.4 | 197.9 | 199.4 | 0.75 | 172.5 | 173.9 | 0.75 | |
19-2 | 197.1 | 36.9 | 200.9 | 175.1 | |||||
19-3 | 195.8 | 36.7 | 199.5 | 174.0 | |||||
HSCC | |||||||||
13-1 | 67.2 | 79.4 | 30.3 | 80.4 | 81.4 | 1.4 | 70.3 | 71.2 | 1.3 |
13-2 | 80.4 | 30.6 | 81.4 | 71.2 | |||||
13-3 | 81.5 | 31.1 | 82.6 | 72.2 | |||||
19-1 | 182.8 | 34.2 | 185.2 | 182.2 | 1.6 | 161.9 | 159.3 | 1.6 | |
19-2 | 179.7 | 33.7 | 182.0 | 159.2 | |||||
19-3 | 177.1 | 33.2 | 179.4 | 156.9 |
4.2 Splice Specimen Tests
Section |
\( {\text{f}}_{\text{c}}^{ '} \)
| Measureda | Moment–curvature method | Measureda | |||||
---|---|---|---|---|---|---|---|---|---|
Measureda | Ave. | (M-Φ)b | Ave. | (M-Φ)c | Ave. |
\( \frac{{{\text{f}}_{s} }}{{\root{{}} \of {{\frac{{{\text{f}}_{\text{c(test)}}^{ '} }}{{{\text{f}}_{\text{c(design)}}^{ '} }}}}}} \)
|
\( \frac{{{\text{f}}_{\text{s}} }}{{\root{ 4} \of {{\frac{{{\text{f}}_{\text{c(test)}}^{ '} }}{{{\text{f}}_{\text{c(design)}}^{ '} }}}}}} \)
| ||
NCC | |||||||||
1 | 39.9 | 341 | 345 | 239 | 284 | 324 | 347 | 353 | 349 |
2 | 350 | 328 | 370 | ||||||
Top | 377 | 377 | 238 | 238 | 321 | 321 | 386 | 382 | |
NSCC | |||||||||
1 | 47.2 | 436 | 424 | 319 | 310 | 403 | 396 | 397 | 410 |
2 | 412 | 301 | 388 | ||||||
Top | 349 | 349 | 271 | 271 | 360 | 360 | 327 | 338 | |
HCC | |||||||||
1 | 66.4 | 427 | 413 | 499 | 458 | 554 | 527 | 421 | 417 |
2 | 399 | 416 | 500 | ||||||
Top | 509 | 509 | 552 | 552 | 567 | 567 | 519 | 514 | |
HSCC | |||||||||
1 | 67.2 | 379 | 416 | 429 | 454 | 510 | 526 | 421 | 419 |
2 | 452 | 479 | 541 | ||||||
Top | 546 | 546 | 562 | 562 | 624 | 624 | 553 | 549 |
Section |
\( (\frac{{f_{\text{s(test)}} }}{{f_{s(M - \phi )} }})_{ave}^{\text{a}} \)
|
\( (\frac{{f_{\text{s(test)}} }}{{f_{s(M - \phi )} }})_{ave}^{\text{b}} \)
|
---|---|---|
NCC | ||
1 | 1.21 | 0.99 |
2 | ||
Top | 1.58 | 1.17 |
NSCC | ||
1 | 1.37 | 1.07 |
2 | ||
Top | 1.29 | 0.97 |
Ave. | 1.36 | 1.05 |
COV (%) | 11.7 | 8.7 |
HCC | ||
1 | 0.90 | 0.78 |
2 | ||
Top | 0.92 | 0.90 |
HSCC | ||
1 | 0.92 | 0.80 |
2 | ||
Top | 0.97 | 0.88 |
Ave. | 0.93 | 0.84 |
COV (%) | 3.2 | 7.0 |
4.3 Comparison of Test Results with Bond Test Database
5 Findings and Conclusions
-
Bond strength of the NSCC was higher than the NCC by approximately 15 %.
-
Bond strength of the HCC was higher than the HSCC by approximately 7 %.
-
No significant difference was observed in the load-slip behavior between the NSCC and NCC and also the HSCC and HCC specimens.
-
The average longitudinal reinforcement steel stress of the NSCC was approximately 15 % higher than the NCC.
-
The average longitudinal reinforcement steel stress of the HSCC was virtually identical with the HCC.
-
The load–deflection behavior of the NSCC and NCC and also the HSCC and HCC beams was essentially identical except for the cracking moment and value at failure.
-
Based on the strain gage measurements, the moment curvature method based on the Popovic, Thorenfeldt, and Collins stress–strain model more accurately predicted the longitudinal reinforcement stress of the NCC and NSCC beams compared with the Hognestad stress–strain model.
-
Based on the strain gage measurements, the Hognestad stress–strain model had better agreement with the HCC and HSCC beam results compared with the Popovic, Thorenfeldt, and Collins stress–strain model.
-
Based on a comparison of the specimens studied in this investigation with a bond database of CC beam specimens, it appears that NSCC and HSCC possess reinforcement bond strength comparable or slightly greater than NCC and HCC, respectively.