The paper presents a description and results of a study focused on the applicability of the sclerometric method to the preliminary assessment of concrete quality in structures after fire. Due to the high thermal inertia, concrete has non-uniform properties in the heated element cross-section. The greatest reduction of concrete compressive strength occurs on the heated surface. When assessing a structure after a fire, it is particularly important to determine the thickness of the damaged external concrete layer. Reinforced concrete beams exposed to high temperature on one side (a one-way heat transfer in the cross-section) for 0 (unheated element), 60, 120, 180 and 240 minutes were examined. A significant decrease of the rebound number on the elements heated surface was observed, depending on the heating duration. The obtained values of the relative rebound number reduction were comparable to the values of relative compressive strength decrease (determined on the basis of temperature) of concrete situated 15 mm from the heated surface.
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1. fib Bulletin 38/2007 “Fire design for concrete structures – materials structures and modelling. State-of-art report” International Federation for Structural Concrete (fib) p. 97 2007.
2. V. R. Kodur “Properties of concrete at elevated temperature” ISRN Civil Engineering 2014: 1-15 2014. DOI: 10.1155/2014/468510
3. R. Kowalski “Mechanical properties of concrete subjected to high temperature” Architecture Civil Engineering Environment 3(2): 61-70 2010.
4. R. Kowalski “The effects of the cooling rate on the residual properties of heated-up concrete” Structural Concrete. Journal of the fib 8(1): 11-15 2007. DOI: 10.1680/stco.2007.8.1.11
5. M. Abramowicz R. Kowalski “The Influence of Short Time Water Cooling on the Mechanical Properties of Concrete Heated up to High Temperature” Journal of Civil Engineering and Management 11(2): 85-90 2005. DOI: 10.1080/13923730.2005.9636336
6. W. Jackiewicz-Rek T. Drzymała A. Kuś M. Tomaszewski “Durability of High Performance Concrete (HPC) Subject to Fire Temperature Impact”. Archives of Civil Engineering 62(4): 73-94 2016. DOI: 10.1515/ace-2015-0109
7. K. Kordina “Design of concrete buildings for fire resistance” Chapter 6 in: Structural Concrete. Textbook on behaviour design and performance. Second edition. Vol. 4. fib Bulletin 54: 1-36 2010.
8. R. Kowalski P. Król “Experimental Examination of Residual Load Bearing Capacity of RC Beams Heated up to High Temperature” Sixth International Conference Structures in Fire Michigan State University East Lansing Michigan USA Proceedings edited by V. K. R. Kodur and J. M. Fransen DEStech Publications Inc. pp 254-261 2010.
9. R. Kowalski “Temperature distribution in R/C cross-section subjected to heating and then freely cooled down in air” Chapter 9 in: Benchmark Studies. Experimental Validation of Numerical Models in Fire Engineering CTU Publishing House Czech Technical University in Prague pp 107-122 2014.
10. Z. P. Bažant M. F. Kaplan “Concrete at High Temperatures. Material Properties and Mathematical Models” Harlow Essex. Longman 1996.
11. G. A. Khoury “Compressive strength of concrete at high temperatures: a reassessment” Magazine of Concrete Research 44(161): 291-309 1992. DOI: 10.1680/macr.19126.96.36.1991
12. P. Marti “Limit analysis and design of concrete and masonry structures” Archives of Civil Engineering 52(2): 351-366 2006.
13. L. X. Xiong “Uniaxial dynamic mechanical properties of tunnel lining concrete under moderate-low strain rate after high temperature” Archives of Civil Engineering 61(2): 35-52 2015. DOI: 10.1515/ace-2015-0013
14. J. Wróblewska R. Kowalski M. Abramowicz „Factors and phenomena affecting the strength of concrete in structures after fire” Materiały Budowlane 539(7): 11-12 2017 (in Polish). DOI: 10.15199/33.2017.07.04
15. M. S. Abrams “Compressive Strength of Concrete at Temperatures to 1600 F” ACI Publication SP25 paper SP25-2 pp 33-58 1971.
16. I. Hager T. Tracz “The Impact of the Amount and Length of Fibrillated Polypropylene Fibres on the Properties of HPC Exposed to High Temperature” Archives of Civil Engineering 56(1): 57-68 2010. DOI: 10.2478/v.10169-010-0003-z
17. G. A. Khoury C. E. Majorana F. Pesavento B. A. Schrefler “Modelling of Heated Concrete” Magazine of Concrete Research 54(2): 77–101. 2002. DOI: 10.1680/macr.188.8.131.52895
18. U. Schneider “Behaviour of Concrete under Thermal Steady State and Non-Steady State Conditions” Fire and Materials 1(3): 103-115 1976. DOI: 10.1002/fam.810010305
19. RILEM TC 129-MHT “Test methods for mechanical properties of concrete at high temperatures” Part 1: Introduction Part 2: Stress-strain relation Part 3: Compressive strength for service and accident conditions Materials and Structures 28(181): 410-414 1995.
20. U. Schneider “Concrete at High Temperatures – A General Review” Fire Safety Journal 13(1): 55-68 1988. DOI: 10.1016/0379-7112(88)90033-1
21. EN 1992-1-2:2004. Eurocode 2: Design of concrete structures - Part 1-2: General rules – Structural fire design.
22. R. Kowalski “Calculations of reinforced concrete structures fire resistance” Architecture Civil Engineering Environment. Journal of the Silesian University of Technology 2(4): 61-69 2009.
23. I. Hager “Methods for assessing the state of concrete in fire damaged structures” Cement Wapno Beton 4: 167-178 2009.
24. E. Annerel L. Taerwe “Techniques for the evaluation of concrete structures after fire” International Conference Application of Structural Fire Engineering Prague Czech Republic pp. 92-96 2011.
25. EN 12504-2:2. Testing concrete in structures - Part 2: Non-destructive testing - Determination of rebound number.
26. ITB Manual 210/1977 “Manual for using Schmidt hammers for non-destructive concrete quality control” Warsaw ITB 1977 (in Polish).
27. EN 13791:2007. Assessment of in-situ compressive strength in structures and pre-cast concrete components.
28. J. Wróblewska R. Kowalski M. Abramowicz “Non-destructive methods of the assessment of concrete in structure after fire” Materiały Budowlane 544(12): 74-75 2017 (in Polish). DOI:10.15199/33.2017.12.22
29. J. Franssen “User’s Manual for SAFIR 2011 A Computer Program for Analysis of Structures Subjected to Fire” University of Liege Belgium 2011.