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

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

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.

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

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

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

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

KFUPM PGNAA setup Neutron generator Hall

KFUPM Accelerator based PGNAA Setup

KFUPM Accelerator-based PGNAA Setup

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

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

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

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

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

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) .

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

Chloride contamination assessment in the plain cement concrete Sample

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.

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

Chlorine Assessment in Silica fume cement concrete

Chlorine Assessment in Fly Ash cement concrete

Chlorine Assessment in Fly Ash cement concrete

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

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.)

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 .

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

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: +1200 hours Pulse Rate: 250 Hz to 20 kHz Pulse Width: Variable, > 5 ms Duty Factor: Variable, 5 to 100%

Portable Neutron Generator Model: MP 320 for field applications

Portable Neutron Generator Model: MP 320 for field applications

Portable Neutron Generator Model: MP 320 for field applications

Portable Neutron Generator Model: MP 320 for field applications

Portable Neutron Generator Model: MP 320 for field applications

Portable Neutron Generator –chloride assessment in Fly ash cement concrete

Portable Neutron Generator –chloride assessment in Fly ash cement concrete

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

Portable Neutron Generator –chloride assesment in Super Pozz cement concrete

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

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 2.86+3.12 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

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

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