ASSESSMENT OF CONCRETE USING NUCLEAR TECHNIQUES

1. A. Naqvi*, O.S. B. Al-Amoudi**, M. Maslehuddin*** *Department of Physics, **Department of Civil Engineering, ***Center for Engineering Research, Research Institute King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia ASSESSMENT OF CONCRETE USING NUCLEAR TECHNIQUES

2. Prompt Gamma Neutron Activation Analysis (PGNAA) technique: • Assessment of concrete contents (calcium, silicon, chlorine , sulfur etc.) using : • 350 keV accelerator-based PGNAA setup • Portable accelerator-based PGNAA setup

3. Introduction • Reinforcement steel corrosion mainly caused by penetration of chloride ions to the steel surface • Saving of billions of dollars in buildings and concrete industry due to early detection of chloride in concrete.. • Critical need for a non-destructive test method to detect chlorides in concrete. • The presently utilized techniques for chloride detection involve difficult and time consuming process of sample retrieval and analysis. • Non-destructive Prompt Gamma Neutron Activation Analysis (PGNAA) technique ideally suited for in-situ elemental analysis of bulk samples.

4. PGNAA technique • Bombardment of atoms in a sample with neutrons • Emission of characteristic prompt -rays of element from excited atoms of the sample via thermal neutrons capture • Intensity measurement of element characteristic prompt -rays • Determination of elemental composition of the sample from measured intensity of characteristic prompt -rays

5. Salient features of PGNAA technique • PGNAA technique- a non-destructive, multi-elemental analysis technique • Analysis of bulk samples (weighing tens of kg) on conveyor belts • Detection capability of light elements such as Si, Al, K Na, Ca, Mg, P, and S • Short analysis time • PGNAA sensitivity : 0.01-50 wt % , adequate enough for on-line analysis • PGNAA technique with on-line detection capability, ideally suited for industrial process control • An accelerator-based PGNAA setup at KFUPM to monitor chloride concentration in concrete

6. Salient features of KFUPM PGNAA setups • Thermal neutron capture based PGNAA setup • 2.8 MeV neutrons from D(d,n) reaction • Pulsed deuteron beam to improve peak/back ground ratio in -ray spectrum • Paraffin & High density Polyethylene based Neutron Moderator • Efficient Gamma Ray Detectors to detect prompt Gamma Rays from Samples • PGNAA sample size calculations through Monte Carlo simulations • Two types of PGNAA setups: • 350 keV accelerator based PGNAA setup • Portable neutron generator based PGNAA setup

7. 350 keV accelerator based PGNAA Setup Basic Features • Thermal neutron capture based PGNAA setup • 2.8 MeV neutrons from D(d,n) reaction • 10-30 μA pulsed deuteron beam to improve peak/back ground ratio in -ray spectrum • Rectangular paraffin & High density Polyethylene based Neutron Moderator • Large cylindrical sample weighing few kg • 10"x 10“ NaI detector • PGNAA sample size calculations through Monte Carlo simulations

8. KFUPM PGNAA setup Neutron generator Hall

9. KFUPM Accelerator based PGNAA Setup

10. KFUPM Accelerator-based PGNAA Setup

11. Measurement of lime/silica ratio in concrete Measurement of fly ash concentration in concrete Chloride Contamination Assessment in the Portland cement Sample Chloride Contamination Assessment in the plain cement concrete samples Chloride Contamination Assessment in the fly ash, silica fume and blast furnace slag cement concrete samples Sulfur concentration Assessment in concrete Some Selected Studiesconducted using KFUPM PGNAA Lab. setup

12. Lime/Silica-Ratioconducted using KFUPM PGNAA Lab. setup • Lime/Silica Ratio Measurements • Measurement of intensity of silicon and calcium prompt gamma rays from concrete • Lime/Silica ratio calculation from intensities ratios

13. Lime/Silica-Ratioconducted using KFUPM PGNAA Lab. setup

14. Measurement of fly ash concentration in concretecontaining 5 and 80 wt. % fly ash

15. Measurement of fly ash concentration in concreteCalcium Prompt Gamma Ray yield from Fly ash cement based concrete specimen containing 5 -80 wt. % fly ash

16. Chloride Contamination Assessment in the Portland cement Sample through 1.165 MeV Chlorine Gamma Ray • The enlarged view of the less interfering 1.165 MeV chlorine prompt -rays spectra for the Portland cement sample containing 1-4 wt % chlorine concentration. • 1.0 wt. % chlorine concentration ( bottom most spectrum), 2 wt % chlorine concentration ( next to bottom most spectrum), 3 wt. % chlorine concentration (next to top most spectrum) and 4 wt. % chlorine concentration ( top most spectrum) .

17. Chloride Contamination Assessment in the Portland Cement Sample • The chlorine Prompt gamma ray measurements from Portland cement sample containing 0.2-4.0 wt. % chloride contamination. • Strong Interference of chlorine gamma rays with energy above 3 MeV with those from calcium in concrete

18. Chloride contamination assessment in the plain cement concrete Sample

19. Chlorine Assessment in Concrete Specimen • The minimum detection limit MDC of chlorine in concrete using for 1.165 and 7.413 MeV chlorine gamma rays is 0.054 0.025 wt % • The maximum permissible limit of chlorine concentration in concrete set by the American Concrete Institute is 0.03 wt. %. • Within a statistical uncertainty of 0.025 wt.%, the MDC within the maximum permissible limit of 0.03 wt. % of chlorine set by ACI Standards.

20. Chloride Contamination Assessment in the fly ash, silica fume and blast furnace slag cement concrete samples

21. Chlorine Assessment in Silica fume cement concrete

22. Chlorine Assessment in Fly Ash cement concrete

23. Chlorine Assessment in Fly Ash cement concrete

25. Sulfur Concentration Assessment in concrete samples • Measurement of sulfur concentration in concrete specimen using 5.421 MeV sulfur prompt gamma ray. • Concrete samples containing 2.0-8.0 wt. % sulfur • Interference of the 5.421 MeV sulfur peak with the double escape peak of calcium. but the intensity of the double escape peak from calcium is insignificant (typically less than 0.5 % of the full energy peak). • The highest 5.421 MeV peak in (6 wt. % conc.), while the smallest peak (2 wt. conc.), % and the middle (4 wt. %. conc.)

26. Sulfur Assessment in Concrete Samples • The MDC of sulfur concentration in concrete for the KFUPM PGNAA setup using the sulfur 5.421 MeV prompt gamma ray was measured to be 0.6000.187 wt %. • MDC is close to the minimum limit of 0.60 wt. % of sulfur in concrete set by British Standards .

27. Assessment of calcium, silicon, and chlorine in concrete using KFUPM Portable accelerator-based PGNAA setup

28. Portable Neutron Generator Model: MP 320 for field applications Max. Yield: 1x108 n/s Max. Lifetime: +1200 hours Pulse Rate: 250 Hz to 20 kHz Pulse Width: Variable, > 5 ms Duty Factor: Variable, 5 to 100% • Digital system • Light weight : 10 kg unit easily integrated into analysis systems, 24 Vdc input, < 75 watts • Less than 500 ns rise time/fall time on source pulse • RS-232 interface works with any PC

29. Portable Neutron Generator Model: MP 320 for field applications

30. Portable Neutron Generator Model: MP 320 for field applications

31. Portable Neutron Generator Model: MP 320 for field applications

32. Portable Neutron Generator Model: MP 320 for field applications

33. Portable Neutron Generator Model: MP 320 for field applications

34. Portable Neutron Generator –chloride assessment in Fly ash cement concrete

35. Portable Neutron Generator –chloride assessment in Fly ash cement concrete

36. Portable Neutron Generator –chloride assessment in Blast Furnace Slag cement concrete

37. Portable Neutron Generator –chloride assesment in Super Pozz cement concrete

38. Portable Neutron Generator –chloride calibration curve for FA, BFS and SPZ cement concrete

39. Portable Neutron Generator –MDC limit for chloride assessment in FA, BFS and SPZ cement concrete

45. Patent Papers under processing for Portable Neutron Generator based PGNAA Setup for onsite concrete analysis

46. Thank You very much