Asphaltene or Polyvinylchloride Waste Blended with Cement to Produce a Sustainable Material Used in Nuclear Safety

Gamma-ray shielding characteristics of concrete containing different percentage of ceramics for different energies

To shield people from dangerous gamma radiation, it is imperative to fabricate inexpensive and environmentally friendly materials. In the present work, suitability of concrete with various % concentrations of ceramics as gamma-ray shielding material has been studied. In this regard, concrete mixture using M-sand and cement with ceramic as filler in different concentrations has been prepared. The mass attenuation coefficients of the prepared samples were measured for different concentrations of ceramics such as 15, 30, 45 and 60%. The mass attenuation coefficients, half value layer (HVL) and tenth vale layer (TVL) of the prepared samples were determined using gamma-ray spectrometer with NaI(Tl) detector at 511, 661.6, 1173, 1332 keV gamma energies. Experimentally obtained mass attenuation coefficients varied from 0.080 to 0.090, 0.074 to 0.086, 0.056 to 0.072 and 0.054 to 0.055 cm2 g-1 at 511, 662, 1173 and 1332 keV, respectively. Therefore concrete mixture with ceramics filler could be a promising shielding material than the bare concrete.

Leaching behavior and compressive strength in the immobilization of Cs-137 contaminated electric arc furnace dust via doping with activated carbon

This study evaluated the potential of an immobilization technique to inhibit the migration and dispersion of Cs-137 contaminated electric arc furnace dust (EAFD) into the environment, by investigating its compressive strength and leaching characteristics. The EAFD was employed to replace ordinary Portland cement (OPC) in varied ratios, ranging from 0 % to 50 % by weight. The replacement was done using various water-binder ratios of 0.35, 0.40, 0.45, and 0.50. Furthermore, the use of activated carbon (AC) has been shown to minimize radionuclide and heavy metal discharge related to its high porosity. AC was added at weight concentrations of 0.5 %, 1.0 %, 1.5 %, and 2.0 %. Compressive strength and leaching tests are used to assess the long-term stability of waste forms and the effectiveness of immobilizing radioactive wastes, which is beneficial for storing and disposing of radioactive waste. The compressive strength is affected by the amount of EAFD, water-to-binder ratios, the addition of AC, and the duration of curing. Measurements of specific surface area, pore size, pore volume, and porosity were also carried out under various conditions. The research results indicate that the addition of AC improves the compressive strength and decreases the release of Cs-137 and heavy metals from the specimen. The mixture of 45 % EAFD and 1.5 % AC is appropriate for efficiently immobilizing Cs-137 contaminated EAFD.

Effective impact of nano-plastic-waste incorporated with nanotitina on the physical, mechanical and microstructural properties of white cement pastes composites for progressing towards sustainability

Plastic waste (PW) has received a lot of attention as a possible additional material for industrial and environmental applications, particularly cement and/or concrete production for a more environmentally and economically sound use of raw materials and energy sources. PW has been investigated as an inert and/or active hydraulic filler for cement and/or concrete by numerous scientists. Plastic garbage is cheap, abundant, and takes long period of time to degrade in the eco-system (soil and water). The main goal of the ongoing research is to offer safety and efficacy by partially substituting nano-plastic waste (NPW), incorporated with nano-titania (NT), for the composition of white cement (WC). Blends are built up by substitution of WC with different ratios of NPW incorporated with fixed ratios of nano-titania (1.0 wt.%). Workability, physical, mechanical and microstructural properties have gone through laboratory and instrumental analysis. The results showed improvement in the compressive strength, density and microstructure due to the effective impact of fillers. Consequently, a decrease in total porosity, whiteness reflection (Ry) and early-rapid expansion. Eventually, the outcomes may reduce the pandemic strength, especially in the external environment, and other epidemics.

Morphological and Gamma-Ray Attenuation Properties of High-Density Polyethylene Containing Bismuth Oxide

For extensive radiation exposure, inventing a novel radiation shielding material is a burning issue at present for the purpose of life saving. Considering this thought, in this study, by adding sundry amounts of Bi₂O₃ into pure high-density polyethylene (HDPE), six HDPE systems were prepared to evaluate the radiation shielding efficiency. These HDPE systems were HDPEBi-0 (pure HDPE), HDPEBi-10 (10 wt% Bi₂O₃), HDPEBi-20 (20 wt% Bi₂O_3-), HDPEBi-30 (30 wt% Bi₂O₃), HDPEBi-40 (40 wt% Bi₂O₃), and HDPEBi-50 (50 wt% Bi₂O₃). The values of the linear attenuation coefficients of the experimental results (calculated in the lab using HPGe) were compared with the theoretical results (obtained using Phy-X software) at 0.060, 0.662, 1.173, and 1.333 MeV energies. To ensure the accurateness of the experimental results, this comparison was made. It was crystal clear that for energy values from 0.06 MeV to 1.333 MeV, all the experimental values were in line with Phy-X software data, which demonstrated the research setup's reliability. Here, the linear attenuation coefficient (LAC), and mean free path (MFP) shielding parameters were assessed. At the energy of 1.333 MeV, sample HDPEBi-0 showed an HVL value 1.7 times greater than that of HDPEBi-50, yet it was 23 times greater at 0.0595 MeV. That means that for proper radiation protection, very-low-energy HDPE systems containing 10-50% Bi₂O₃ could be used; however, the thickness of the HDPE system must be increased according to the energy of incident radiation.

Influence of Graphene Nanoplates on Dispersion, Hydration Behavior of Sulfoaluminate Cement Composites

Sulfoaluminate cement (SAC) is a low carbon ecological cement with good durability and is widely used in various projects. In addition, graphene nanoplates (GNPs) have excellent thermal, electrical, and mechanical properties and are excellent nano-filler. However, the hydration behavior of GNPs on SAC is still unclear. In this paper, the effect of GNPs on SAC hydration was investigated by isothermal calorimetry, and the hydration kinetic model and hydration kinetic equation of SAC was established, explaining the differences in cement hydration processes with and without GNPs on SAC based on a hydration kinetic model. Results indicate that the hydration exotherm of SAC mainly includes five stages: the initial stage, the induction stage, the acceleration stage, the deceleration stage, and the stable stage. The addition of GNPs promoted the hydration exotherm of SAC and accelerated the hydration reaction. Different from the hydration reaction of Portland cement, the hydration reaction of SAC is mainly a diffusion–reaction process.