Is there any reference about the relation between the flexural and flexural toughness in High strength concrete?
Hi Mohammad Ali
You need to clarify the applied toughness test method. Toughness or post-crack behaviour can be measured by different methods, they can be classified in three main categories and the results depend on the applied test method:
1- Measuring the absorbed energy based on the area analysis under the load-deflection curve
2- Measuring the residual load based on capacity of sample after its peak load
3- Measuring of absorbed energy using fracture theory and the critical crack length
I assumed the measured toughness was based on the absorbed energy methods (group 1). Absorbed energy methods can be sub-classified as follows:
Toughness by ACI 544 procedure
Toughness by ASTM 1018 procedure
Toughness by JSCE-G 552 procedure
Toughness by ASTM C1609 procedure
Brittleness Index (BI) Method
ASTM C1550
Barr and Liu Toughness Index (TI)
Wang and Backer Toughness Index
Trottier and Banthia Toughness Index
South African Toughness Method
RILEM TC162-TDF Toughness Method
Which toughness test method did you apply?
Were the tested samples steel-fibre concrete ?
Dear Iman
Thanks for your attention and comprehensive answer. The ASTM C1609 (2006) was used for doing test. This test involves four point flexural loading. The beam size was 100*100*500 mm with the span of 300 mm and load distance of 100 mm. One sample with four points within deflection measurement under universal machine loading with two LVDT in middle of span and two sides of beams. The flexural toughness calculated due to area under the load versus net deflection curve 0 to 2 mm (l/150). I found that there could be relation between flexural and toughness after data analyzing, but i could not find any references about it.
Hi Mohammad Ali, I've used ASTM 1609 for rubbrised concrete samples and have some experience with that test.
https://www.researchgate.net/publication/280082662_Shrinkage_performance_of_Crumb_Rubber_Concrete_%28CRC%29_prepared_by_water-soaking_treatment_method_for_rigid_pavements
Based on my experience there shouldn't be that much deflection for high-strength concrete (f'c28=65 MPa or higher), unless it is steel fibre reinforced.
l/600 (0.5mm) deflection would be would be more appropriate. I think you need to be sure that LVDT should be set up in the way that ASTM C1609 has mentioned. it should be referenced to the sample and not the testing machine.
You may find the following articles helpful:
Alam MR, Azad MAK, Kadir MA (2010) Fracture toughness of plain concrete specimens made with industry-burnt brick aggregates. 38:81–94.
Banthia N, Sappakittipakorn M (2007) Toughness enhancement in steel fiber reinforced concrete through fiber hybridization. Cement and Concrete Research 37:1366–1372.
Banthia, Nemkumar, Ashish Dubey (1999) Measurement of Flexural Toughness of Fiber-Reinforced Concrete Using a Novel Technique. Part 1: Assessment and Calibration.
Barr BIG, Liul K (1982) A toughness index to measure the energy absorption of fibre reinforced concrete. The Intemationa/ Journal of Cement Composites and Lightwelght Concrete 4:221–227.
Hamoush S a., Abdel-Fattah H (1996) The fracture toughness of concrete. Engineering Fracture Mechanics 53:425–432. doi: 10.1016/0013-7944(95)00107-7
Islam ST (2012) Study of some parameters affecting the measured flexural toughness of fiber reinforced concrete. The University of British Columbia
Jenq YS, Shah SP (1985) A Fracture toughness criterion for concrete. Engineering Fracture Mechanics 21:1055–1069. doi: 10.1016/0013-7944(85)90009-8
Karihaloo BL (1986) Fracture toughness of plain concrete from compression splitting tests. International Journal of Cement Composites and Lightweight Concrete 8:251–259. doi: 10.1016/0262-5075(86)90052-7
Mindess S, Chen L, Morgan DR (1993) Determination of the First-Crack Strength and Flexural Toughness of Steel Fiber-Reinforced Concrete.
Wang Y, Backer S (1989) Toughness determination for fibre reinforced concrete. International Journal of Cement Composites and Lightweight Concrete 11:11–19. doi: 10.1016/0262-5075(89)90031-6
Article Shrinkage performance of Crumb Rubber Concrete (CRC) prepare...
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