1. ASSESSMENT OF CONCRETE USING NUCLEAR TECHNIQUES
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

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 : 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. Some Selected Studies conducted using KFUPM PGNAA Lab. setup
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

12. Lime/Silica-Ratio conducted 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-Ratio conducted using KFUPM PGNAA Lab. setup

14. Measurement of fly ash concentration in concrete containing 5 and 80 wt. % fly ash
Element
(wt. %)
Sample
5 wt.%-FA
80 wt. %-FA H
1.03
0.762 C
5.98
4.89 O
52.19
49.6 Mg
0.28
0.45 Al
0.49
2.09 Si
15.31
16.04 S
0.187
0.25 K
0.162
0.13 Ca
23.93
21.71 Fe
0.36
0.81

15. Measurement of fly ash concentration in concrete Calcium Prompt Gamma Ray yield from Fly ash cement based concrete specimen containing 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 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 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 and MeV chlorine gamma rays is 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

24. E
(MeV)
MDC
(wt. %) in blast furnace slag concrete [8]
(wt. %) in fly ash cement concrete [10]
(wt. %) in silica fumes cement concrete
1.16 -
0.0220.007
0.0210.009
1.94
0.0510.015
0.0380.011
5.72
6.11
0.034  0.011
0.038  0.017
0.026  0.008
6.62
0.038  0.012
0.059  0.027
0.058  0.018
7.41
0.044 0.013
0.050 0.027
0.026 0.008
7.79
0.060 0.018
0.076 0.029
0.063 0.019
8.58
0.076 0.023
0.068 0.029
0.081 0.025

25. Sulfur Concentration Assessment in concrete samples
Measurement of sulfur concentration in concrete specimen using MeV sulfur prompt gamma ray.
Concrete samples containing wt. % sulfur
Interference of the 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 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 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
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
Max. Yield: 1x108 n/s
Max. Lifetime: hours
Pulse Rate: 250 Hz to 20 kHz
Pulse Width: Variable, > 5 ms
Duty Factor: Variable, 5 to 100%

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. Minimum Detectable Concentration (MDC), % of cement
Portable Neutron Generator –MDC limit for chloride assessment in FA, BFS and SPZ cement concrete
Gamma-Ray
Energy (MeV)
Minimum Detectable Concentration (MDC), % of cement
FA Concrete
BFS Concrete
SPZ Concrete
0.033±0.010
0.034±0.010
0.032±0.012
5.72
0.031±0.010
0.032±0.010
0.037±0.012
6.11
0.035±0.012

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

46. Thank You very much