Radiological characterisation of recyclable industrial by-products for concrete production point of view

QUB, MONDAY, NOVEMBER 12, 2018

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“The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 701932”

Z. Sas1,2*, N. Vandevenne2, R. Vinai3, J. Kwasny1, M. Soutsos1, W. Sha1, R. Doherty1, M. Russel1, W. Schroeyers2

1School of Natural and Built Environment, Queen's University Belfast, UK2Hasselt University, CMK, Nuclear Technological Centre (NuTeC), Faculty of Engineering Technology, BE

3College of Engineering, Mathematics and Physical Sciences, IK

• Generally, the natural radiation is severalmagnitudes higher than from artificial sourcese.g. nuclear industry

• Th-232, K-40, U-238, (Ra-226) and theirprogenies

• Unknown risk factor or ignored

• As result of elevated indoor spent time, theisotopes found in BMs can significantlycontribute to radiation exposure

Why it is important?

Main reason of the studyWhat it is important to deal with Natural Origin Radioisotopes (NOR)?

REQUIRED TASKS REGARDING THE REUSE OF BY-PRODUCTS IN BM INDUSTRY

• The screening of BP is necessary to avoid elevated risk from radionuclide content

• Smart design of BMs’ internal stucture is required to reduce the radon and

thoron exhalation

• The leaching of radionuclides

EU-BSSCOUNCIL DIRECTIVE 2013/59/EURATOM

• In the EU to control the gamma-exposure originated from

BMs, the I-index is recommended for the member states

to screen them

kgBq

C

kgBq

C

kgBq

CI KThRa

/3000/200/300

40232226

• The I-index value of 1.0 can be used as a conservative screening tool for identifying materials

that during their use would cause doses exceeding the reference level

(1 mSv/y excess in addition to outdoor exposure) in the case of bulk amount inbuilt

• For application of the index to such constituents, in particular residues from industries

processing NORM recycled into BMs, an appropriate partitioning factor needs to be applied

Geopolymer team in SNBE• Experience geopolymer preparation &

characterization• Excellent university and infrastructure

NuTeC in UHasselt• Great experience in NORMs• Excellent infrastructure for radiological

characterization• Leader of COST TU1301 NORM4Building

Action

By-BM GEOPOLYMERSBy-products and samples

CKD; PFA; GGBS

Full material character.Mechanical and iternal structure

Radiological character.Gamma spect.; I-index; Rn-222 em/ex

Screening of by-products and componentsNOR content determination by HPGe gamma sepctrometry

Sample ID Material Industry

APC Air Pollution Control Cement production

BA Bottom Ash Coal combustion thermal power plant

CKD × 3 Cement Kiln Dust Cement production

FA × 7 Fly Ash Coal combustion thermal power plant

GGBFS × 2 Ground Granulated Blast-Furnace Slag Ferrous industry

HWA Household Waste Ash Municipal waste incineration

ISSA Incinerated Sewage Sludge Ash Sewage sludge incineration

RHA Rice Husk Ash Rice milling industry

RM × 2 Red Mud Alumina production

Screening of by-products and componentsNOR content determination by HPGe gamma sepctrometry

NOR content of the surveyed samplesGamma spectrometry results

• The Ra-226, the Th-232 and the K-40 content of the industrial by-products were found between 5.5-200.5 Bq/kg; 7.3-452.4 Bq/kg; and36.4-2712.1 Bq/kg with an average of 91.9 Bq/kg; 89.7 Bq/kg; and748.8 Bq/kg, respectively.

• Compared to the world average of NORs in construction materials(Ra-226 = 50 Bq/kg, the Th-232 = 50 Bq/ kg and the K-40 =500 Bq/kg(European Commission, 1999))

• The obtained average values of the by-products were 1.84, 1.79 and1.50 times higher related to Ra-226, Th-232 and K-40 content of theworld average.

Main chemical componentsXRF results

NOR isotopes vs chemical composition

• Correlation analysis was performed to examine the possibility of using the information aboutthe chemical composition as a source apportionment tool for NORs.

• Based on the Pearson correlation results, the strong correlation results – either the positive andnegative ones – shows that the concept is promising to predict the level of the expected NORs

• However, the conclusion was drawn from 19 samples the extension of the dataset and furthercorrelation analysis could strengthen the concept

Screening of by-products and componentsRadon exhalation and emanation with accumulation chamber technique

• Drying, grinding <2 mm

• Radon-proof Plexy chambers

• Optimum 3-4 days

• Closed-loop sampling

Sample preparation

Accumulation chamber

Accumulation

Sampling

Calculation

Screening of by-products and componentsRadon exhalation and emanation with accumulation chamber technique

Conclusions

• No extraordinary NOR content in the case of any of the samples. Compared withrecently published NOR databases the values were close to the average values ofthe datasets.

• Significant positive correlation was found between the Ra-226 and the Al2O3;BaO; Fe2O3 content and strong negative correlation were found with the K2Ocontent. Strong negative correlation was observed between the Na2O and CaOcontent. Th-232 had a strong positive correlation with the Cr2O3; Fe2O3; Na2O;TiO2; V2O5 and ZrO2 content. The K-40 content had a strong positive correlationwith the CaO and the K2O content while strong negative correlation was foundwith the BaO content.

• The massic exhalation demonstrated a broad range. The highest values werefound in the case of the red mud samples.

• The emanation coefficients were significantly lower in the case of the by-productsgenerated under high-temperature processes. Compared with literature data(International Atomic Energy Agency, 2013) all the emanation factors are regular.

• These emanation coefficients, chemical correlations state could be used to sourceapportion materials found during the process of landfill mining and recovery ofmaterial for recycling.

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“The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 701932”

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Thank you for your kind attention!!!