Comparing the efficiency of fly ash geopolymer attenuation and cement mortar as diagnostic x-ray shielding materials through theory and experiment

This study compared ordinary Portland cement (OPC) and Fine Aggregate Graded Polymer (FAGP) samples mixed with 0%, 5%, 10%, and 15% barium sulfate (BaSO4). Theory using the XCOM program and experiments using x-ray fluorescence (XRF) within a specified energy range of 16–25 keV were used to calculate the samples’ mass attenuation coefficients. The comparison involved calculating the linear attenuation coefficients (μ/ρ) and attenuation coefficients (μ) of the samples. Both theoretical and experimental results show that the FAGP containing 15% BaSO4 at 16.61 keV has the best attenuation. The findings show that BaSO4 improves radiation shielding. A negative association was found between the attenuation coefficient (μ) and the energy level of radiated radiation. The analysis also found significant concordance between experimental and theoretical methods. In conclusion, the XCOM program had slightly higher mass attenuation coefficients, especially at lower energy levels.


Introduction
The fundamental mechanism of radiation Shielding is based on the idea of attenuation, which is the ability to decrease the penetration of radiation by blocking or redirecting particles using a barrier material.However, the distribution and depth of radiation differ based on the type of radiation.The linear attenuation coefficient, represented as μ (cm −1 ), varies based on the shielding material and the energy of the photons.The way photons and matter interact depends on the energy of the photon and the density of the material used for shielding [1][2][3][4].
Over the recent years, there has been a significant focus on conducting comprehensive studies aimed at improving the effectiveness of radiation shielding in various materials.These materials include but are not limited to ordinary concrete, heavy concrete, lead, steel, polyethylene, paraffin, and wood [49].The utilization of lead as a shielding material against radiation in concrete walls or in isolation has been widely practiced.However, the poisonous nature of lead has prompted researchers to explore alternate alternatives [1,2].The utilization of lead in various radiation shielding devices has implications for both human health and the surrounding environment.Novel high-density materials that are non-toxic have the potential to replace traditional materials such as lead in several applications, including but not limited to vibration dampening, weighting, balancing, and radiation shielding [50].
Concrete is commonly used in building reactor shielding.The composition mostly comprises Portland cement, sand, coarse particles, and water.Concrete is a suitable material for radiation shielding since it can efficiently reduce the intensity of both neutron and gamma rays.Researchers have attempted to enhance the density of concrete by substituting or partially substituting traditional fillers (such sand, gravel, and broken rocks) with elements that have higher specific gravity, such as magnetite, hematite, barite, and colemanite [39,[51][52][53][54], although very few of these studies have emphasized on enhancing the density of concrete for shielding purposes [52].An example of a barite mortar batch is the combination of cement, sand, water, and barium sulphate.Barite mortar is extensively utilized in radiology departments as a shielding material against x-ray radiation due to its exceptional attenuation properties, convenient handling characteristics, cost-effectiveness, and widespread availability [1,39,55].BaSO 4 base is an ideal material for shielding the effects of radiation [56].However, BaSO 4 only produces a good shielding effect when it is uniformly distributed over other materials because of its high density (4.5 g cm −3 ).
In addition, geopolymer paste is largely used as an alternative binder to OPC pastes in the production of concrete.Although fly ash (FA) is a source material for readily available geopolymer binders, its current use is limited.More specifically, the use of FA has fell below 15%, even though the global coal ash production exceeds 390 million tons each year, [57].Therefore, the exploitation of FA as a binder in concrete is important in order to make it more environmentally viable [58].Moreover, fFAGP can serve as an alternative to OPC because of its potential radiation shielding capacity.FAGP is a non-toxic material that does not emit greenhouse gases during emission.Dense and high atomic number (Z eff ) materials such as BaSO 4 are added to FAGP to enhance its shielding properties.
This investigation aims to assess the influence of BaSO 4 on the radiation shielding effectiveness of FAGP, investigate variations in radiation attenuation as photon energy increases, and conduct a comparative analysis of theoretical (XCOM software) and experimental (XRF) methodologies for determining attenuation coefficients.The successful achievement of these objectives will validate the viability of employing FAGP as a proficient and environmentally safe material for shielding against radiation.

Methods
We acquired the FA from a power station in Perak, Malaysia.We obtained the alkaline activator, which includes sodium hydroxide (NaOH) and sodium silicate (Na2SiO3).The river sand has a 1.6% water absorption rate and a 2.65 specific gravity.A certain amount of commercial BaSO 4 was acquired.

OPC preparation
The production of OPC involved the combination of 500 g of OPC with 1375 g of sand at a ratio of 2.75.The mixer processed the mixture for 10 min.Then, we added 245 grams of water to the mixture, maintaining a ratio of 0.49 [59].Subsequently, the combination underwent a 10 min period of mechanical mixing in order to acquire a newly prepared blend of OPC.The OPC was introduced into conventional steel molds with dimensions of 5 cm × 5 cm × 5 cm.The molds were subjected to vibration for a duration of 15 s using a vibrating table.Following this, the molds were left undisturbed at ambient temperature for a period of 24 h.Afterward, the specimens remained submerged in water for 28 days.OPC materials of varying thicknesses of 3, 6, and 9 cm were produced, as depicted in figure 1.

FAGP preparation
A Mixed Design Excel spreadsheet was employed to generate the FAGP batch by inputting the ratios of liquid alkaline/FA, sodium silicate/NaOH, additional water, and sand/FA.The weight of the FAGP components (FA, sand, Na2SiO3, NaOH pellet, water, and additional water ingredients) is computed automatically using the table.The weights assigned to the components of the FAGP are as follows: The experimental setup consisted of 859 grams of fatty acid (FA), 1290 grams of sand, 40 grams of sodium hydroxide (NaOH), 275 grams of sodium silicate (Na2SiO3), 90 grams of water (H2O), and an additional 60 grams of water [60].(Please note that the materials and their amounts are present in appendix (table A 1)).The FAGP materials were mixed until .the batch was attained [61].The mixture that was acquired was subsequently poured into the steel molds, as depicted in figure 2. The samples were subjected to vibration for a duration of 10 s by utilizing a vibrating table.Subsequently, the samples were held under ambient conditions for a duration of 24 h.In order to prevent moisture loss, the molds were covered with vinyl sheeting.Subsequently, the specimens were subjected to thermal treatment in an oven set at a temperature range of 60 °C-70 °C for a duration of 24 h.The samples were subsequently extracted from the experimental setup and allowed to undergo a cooling process under ambient conditions, namely in a temperature range of 22 to 25 degrees Celsius, for a duration of 28 days.Following the completion of the fabrication process, the samples underwent EDX analysis to ascertain the elemental percentages.These percentages are subsequently utilized in the calculations of Zeff.

X-ray fluorescence (XRF)
In this study, XRF was employed to ascertain the attenuation coefficient (μ) and mass attenuation coefficient (μ/ ρ) values of the FAGP, FAGP with varying concentrations of BaSO 4 (5%, 10%, and 15%), as well as OPC.The XRF photon was released from a γ source containing high-purity americium (241 Am).This source is known to have a nominal activity of 3.7 gigabecquerels (GBq) and was manufactured in the year 1990.The experimental configuration of this investigation is depicted in figure 2. The photon energy of XRF emissions is dependent on the metal target (metal plate) used in the selected low energy range.The attenuation of XRF photons was detected by using a germanium (LE-Ge) detector.

Accuracy of the XRF system
The XRF system's accuracy was assessed through the accurate determination of the attenuation coefficient (μ) and mass attenuation coefficient (μ/ρ) of aluminum.The aluminum material that was subjected to testing has a notable level of purity, measuring at 99.9%.The material's thickness, on the other hand, varies across different samples, measuring at 0.01 cm, 0.06 cm, 0.16 cm, and 0.325 cm, respectively.In order to establish the correlation between the natural logarithm of the initial intensity (Io) to the transmitted intensity (I) and the thickness of aluminum (Al) at an energy level of 17.48 keV, the material under investigation underwent an irradiation period lasting 2000 s.The natural logarithm of the initial intensity divided by the current intensity was then graphed as a function of thickness.The attenuation coefficient (μ) was determined by calculating the slope of the line, as depicted in figure 3.
The mass attenuation coefficient calculated using equation (2) The densities of all samples were determined from measurements of their weights and external dimensions (values) using a Vernier calliper and balance, respectively, as shown in figure 4.
The measurement was based on the assumption that the densities of the samples are uniform.Moreover, the density (ρ) can be determined by dividing the mass of an object by its volume, expressed in grams per cubic centimeter (g/cm 3 ).The length, width, and thickness of each sample were measured using a digital micrometer caliper, while the mass of each sample was determined using an electronic balance.The volumes of the test samples were determined by employing equation 3.
Where r, m and V represent the density, mass and volume of the samples, respectively.The density of the samples is outlined in table 1.

XCOM software
One can classify the substance for cross-sectional measurements as an element, compound, or mixture.The XCOM program calculated standard energy values.The following section describes the information used to prepare a specific form with multiple options: (a) The mixtures in this study are composed of elemental components.
(b) The chemical symbol or formula is explicitly indicated, along with the weight fraction for each constituent, as depicted in figure 5.
(c) The output limit is established at specific energy levels.According to the data presented in table 2, the μ/ρ values for OPC and FAGP are 4.85 and 4.80 cm 2 g −1 , respectively.This suggests that the mass attenuation of OPC is superior to that of FAGP.The introduction of BaSO 4 at concentrations of 5%, 10%, and 15% to the FAGP resulted in an elevation of the mass attenuation coefficients (μ/ρ) of the materials to 5.03, 5.10, and 5.28 cm 2 g −1 , respectively.This implies that the inclusion of BaSO 4 in FAGP results in an increase in μ/ρ, hence enhancing the radiation shielding efficacy of FAGP.The mass attenuation coefficient (μ/ρ) increased as the percentages of BaSO 4 rose, ranging from 5.88 to 6.44 cm 2 g −1 .The observed increase in impact can be attributed to the specific density (4.5 g cm −3 ) and Zeff value (45.42) of BaSO 4 .As indicated in table 2, there exists a resemblance in the μ/ρ values derived from the XCOM program and XRF analysis.Notably, the OPC and FAGP (0% BaSO 4 ) exhibit the highest degree of proximity.

Mass attenuation coefficient (μ/ρ) at 17.47 keV
The mass attenuation coefficients (μ/ρ) of the samples were determined at an energy of 17.47 keV using the XCOM software and XRF setup as described in section 3.5.According to the data shown in table 3, it can be observed that the mass attenuation coefficient (μ/ρ) of OPC is greater (4.36 cm 2 g −1 ) compared to FAGP (4.31 cm 2 g −1 ).The μ/ρ value exhibited an increase from 4.51 to 4.82 cm 2 g −1 as the amount of BaSO 4 in FAGP grew from 5% to 15%.
The findings suggest that the incorporation of BaSO 4 into FAGP enhances its ability to provide radiation protection, mostly attributed to the high density of BaSO 4 (4.5 g cm −3 ).The sample containing 15% BaSO 4 in FAGP exhibited the highest level of attenuation at 17.47 keV, as observed in table 3, when compared to the other samples.The XCOM software yielded mass attenuation coefficient (μ/ρ) values of 4.71 and 4.75 cm 2 g −1 for OPC and FAGP, respectively, suggesting a significant similarity between the two materials.The values of μ/ρ exhibited an upward trend as the percentages of BaSO 4 rose.

Mass attenuation coefficient (μ/ρ)at 21.18 keV
Table 4 presents the μ/ρ values acquired through the use of XCOM software and empirically determined use an XRF setup for all samples at an energy level of 21.18 keV.The similarity of the μ/ρ values is apparent based on respectively.This indicates that adding BaSO 4 improves FAGP's radiation shielding capability compared to OPC or FAGP alone.The findings from the XCOM software align with the outcomes observed by XRF analysis.There is a link between the amount of BaSO 4 in FAGP material and the increase in attenuation that was seen in both computational analysis (XCOM) and experimental measurements (XRF).Furthermore, the measured mass attenuation coefficients (μ/ρ) at 22.16 keV exhibit relatively lower values when compared to the recorded values at 21.17 and 17.47 keV.
According to the data presented in table 6, the mass attenuation coefficient (μ/ρ) values for the OPC are marginally greater than those for the FAGP, measuring at 1.65 and 1.61 cm 2 g −1 , respectively.The μ/ρ values of the FAGP subsequently exhibited a rise to 1.70, 1.91, and 2.05 cm 2 g −1 , corresponding to the incorporation of 5%, 10%, and 15% BaSO 4 , respectively.The elevated density (4.5 g cm −3 ) and effective atomic number (Zeff) value (45.42) of BaSO 4 contribute to the observed rise in μ/ρ.These properties enhance the radiation shielding capability of the material, resulting in the observed increase in μ/ρ.The findings obtained using the XCOM software align with the experimental data obtained from XRF analysis, as indicated in table 6.The maximum μ/ ρ value (2.05 cm 2 g −1 ) was achieved for the composite material FAGP containing 15% BaSO 4 , thereby indicating the efficacy of FAGP in providing radiation shielding capabilities.Both experimental (XRF) and computational (XCOM) findings indicate that the mass attenuation coefficient (μ/ρ) values obtained at 25.27 keV exhibit comparatively lower values compared to those observed at lower energies.

The linear attenuation coefficient (μ) as a function of energies
The graph in figure 6 shows how the attenuation coefficient (μ) and photon energies change in a way that is opposite to what you might expect.It shows this for three different materials: OPC, FAGP, and FAGP with different amounts of BaSO4 (5%, 10%, and 15%).The maximum attenuation coefficient (μ) value observed was 11.67 cm −1 for the sample containing 15% BaSO 4 in FAGP at an energy level of 16.61 keV.On the other hand, the minimum value of μ (4.52 cm −1 ) was observed for the sample FAGP containing 15% BaSO 4 at an energy level of 25.27 keV.The plot demonstrates a negative correlation between the attenuation coefficient (μ) and the energy of the emitted radiation, as higher energy levels are associated with lower attenuation coefficients.Overall, the findings suggest that the utilization of FAGP containing 15% BaSO 4 exhibits promising potential as a material for radiation shielding purposes, particularly in low energy environments.

Conclusion
This study looks into how to find the mass attenuation coefficients for OPC and FAGP mixed with BaSO 4 .It does this by using both experimental (XRF) and theoretical (XCOM) methods.The findings demonstrated concurrence between the experimental and theoretical methodologies, albeit with a minor advantage in mass attenuation coefficients observed in the XCOM program, particularly at lower energy levels.When FAGP samples were mixed with 15% BaSO 4 , they had higher attenuation (μ = 5.28) and mass attenuation factors (μ/ρ = 6.44 cm 2 g −1 ) than cement mortar (μ = 4.85, μ/ρ = 5.44 cm 2 g −1 ).This suggests that the combination of FAGP and BaSO 4 had superior radiation shielding capabilities when compared to OPC.The findings suggest that the incorporation of BaSO 4 leads to an enhancement in radiation shielding capability.The findings additionally demonstrated a negative correlation between the attenuation coefficient (μ) and the energy level of the emitted radiation.FAGP exhibits superior shielding properties compared to cement, especially in lowenergy diagnostic x-ray applications.The investigation provides confirmation that the combination of FAGP and BaSO 4 exhibits potential as a suitable substitute material for various construction materials employed in radiation shielding applications.

Figure 1 .
Figure 1.This figure presents an overview of the materials and procedures involved in the preparation of OPC.The essential components for OPC preparation are OPC itself, sand, water, a mixing machine, steel moulds, and prepared OPC samples.

Figure 4 .
Figure 4. Balance and venier calliper used to calculate density.

Table 1 .
The densities of sample materials.
Figure 5.The integration of element symbols and fractional weights into the XCOM program is being considered.3.Result and discussion3.1.Measurement of mass attenuation coefficient (μ/ρ) 3.1.1.Mass attenuation coefficient (μ/ρ)at 16.61 keV The elemental percentages of OPC, FAGP, FAGP + 5% BaSO 4 , FAGP +10% BaSO 4 , and FAGP +15% BaSO 4 materials were measured at specific energy levels (16.61, 17.47, 21.17, 22.16, and 25.27 keV) within the energy range of 0.01-0.1 MeV.These measurements were then utilized as input in the XCOM software, as described in section 3.4, to calculate the mass attenuation coefficient (μ/ρ) values.The values of μ/ρ were determined through experimental measurements for each of the samples at an energy level of 16.61 keV using an XRF apparatus, as illustrated in table 2.

table 4 .
The XRF analysis revealed that the specific surface area values (μ/ρ) for OPC and FAGP are 2.64 and 2.60 cm 2 g −1 , respectively.The XRF technique yields μ/ρ values that exhibit a direct proportionality to the percentage rise of BaSO 4 in the analyzed materials.The μ/ρ values obtained by the XCOM program (table 4) exhibit a comparatively higher magnitude compared to the XRF results, except for the case of FAGP + 15% BaSO 4 .The μ/ρ values exhibited a corresponding improvement as the percentages of BaSO 4 in the FAGP increased.The measured mass attenuation coefficients (μ/ρ) at 21.17 keV exhibit relatively lower values compared to those seen at 17.47 keV, suggesting a decrease in attenuation with an increase in x-ray or radiation energy.We found the mass attenuation coefficient (μ/ρ) values by measuring them with XRF and then using the XCOM software to figure them out at an energy level of 22.16 keV, as shown in table5.The μ/ρ values of the OPC and FAGP exhibit similarity, with corresponding values of 2.34 and 2.31 cm 2 g −1 .Additionally, adding 5%, 10%, and 15% of BaSO4 to the FAGP in the experiment led to higher μ/ρ values of 2.45, 2.65, and 2.67 cm 2 g −1 ,

Table A 1
. Materials and their amounts that used in mixture preparation.