-
Research Article
Experimental Study to Measure Conductive Heat Transfer Properties in New Materials with Environmental Waste Aggregates
Andrés Emanuel Díaz*
,
Alejandro Luís Hernandez
Issue:
Volume 13, Issue 2, April 2025
Pages:
17-27
Received:
7 February 2025
Accepted:
19 February 2025
Published:
18 March 2025
Abstract: This study presents the design, development, and operational evaluation of the HD25 Hot Box, a guarded hot plate apparatus designed to measure the thermal conductivity of concrete specimens under steady-state conditions. The HD25 Hot Box was developed to assess the heat transfer properties of construction materials, particularly those incorporating environmental waste aggregates such as high- and low-density polyethylene and perlite. The device adheres to the Argentine standards IRAM 11559, IRAM 11549, and IRAM 11601, ensuring accurate and reliable measurements. The apparatus consists of two main units: a heating unit and a cooling unit, which work in tandem to establish a uniform, one-dimensional heat flow through prism-shaped concrete specimens. The HD25 Hot Box measures key thermal properties, including thermal conductivity, resistivity, resistance, and transmittance. The study highlights the impact of incorporating plastic waste into concrete, demonstrating that replacing traditional aggregates with plastic waste reduces the material's density and thermal conductivity while increasing its thermal resistance and resistivity. For instance, replacing 37% of coarse aggregate with plastic resulted in a 40% reduction in thermal conductivity and a 68% increase in thermal resistance compared to conventional concrete. The device's design includes a central heating plate surrounded by a guard section to ensure uniform heat distribution, and a cooling unit that uses a closed-loop water circulation system to maintain temperature stability. The HD25 Hot Box is compact, lightweight, and energy-efficient, making it suitable for laboratory use. The study concludes that the HD25 Hot Box is a reliable tool for evaluating the thermal properties of concrete, particularly those incorporating recycled materials, and provides valuable data for energy-efficient building design. The findings suggest that replacing up to 19% of traditional aggregates with plastic waste and perlite fines is optimal for maintaining both thermal and mechanical properties in construction materials.
Abstract: This study presents the design, development, and operational evaluation of the HD25 Hot Box, a guarded hot plate apparatus designed to measure the thermal conductivity of concrete specimens under steady-state conditions. The HD25 Hot Box was developed to assess the heat transfer properties of construction materials, particularly those incorporating...
Show More
-
Research Article
A Physics Model for Origin of Life
Issue:
Volume 13, Issue 2, April 2025
Pages:
28-30
Received:
17 February 2025
Accepted:
5 March 2025
Published:
10 April 2025
Abstract: In this article, we attempt to convince the reader that the origin of life was such an exceptionally unlikely event that it probably has never occurred elsewhere. This involves an explicit calculation using the laws of physics which, while speculative, may encapsulate the essential science without knowledge of biological details. Making only physics, and no biology, assumptions about the origin of the first single celled organism (SCO) on Earth, we adopt methods of quantum tunnelling to make an estimate of the probability PSCO for the origin of life. We argue that before the time tSCO laws of physics must suffice and assume a first-order phase transition which nucleates at the first SCO production. In the classical limit where Planck's constant vanishes h → 0, PSCO also vanishes and remains extremely small for the correct value of $h$. Thus quantum mechanics plays a central role in permitting life to form. We compare the resultant probability with the expected number of exoplanets in the Milky Way (~1012) and the Visible Universe (~1024) and conclude that the probability of extraterrestrial life in the Visible Universe is infinitesimal. This result suggests that the visible universe is a lonely place for humankind because extraterrestrial life will never be encountered.
Abstract: In this article, we attempt to convince the reader that the origin of life was such an exceptionally unlikely event that it probably has never occurred elsewhere. This involves an explicit calculation using the laws of physics which, while speculative, may encapsulate the essential science without knowledge of biological details. Making only physic...
Show More
-
Research Article
Comparison of Public Indoor Internal Exposure from Radon-222 Inhalation in the Different Dwellings of 09 Regions of Madagascar
Issue:
Volume 13, Issue 2, April 2025
Pages:
31-37
Received:
12 March 2025
Accepted:
26 March 2025
Published:
17 April 2025
DOI:
10.11648/j.ajpa.20251302.13
Downloads:
Views:
Abstract: Radon is the radioactive gas naturally present in the environment produced by natural radioactive decay of uranium-238. It is uncolored and inodorous and present in outdoor air as well as in dwelling spaces. In nine (09) regions of Madagascar, radon study was carried out for indoor radon concentration measurement in 62 dwellings spread. The aim of this study is to compare the indoor internal exposure due to Radon inhalation. AphaGuard and SARAD equipment were used. The radon concentration and the annual effective dose vary respectively from (4.37 ± 1.74) Bq.m-3 to (77.80 ± 4.51) Bq.m-3 with average value of (31.04 ± 7.78) Bq.m-3 and from (0.14 ± 0.05) mSv.y-1 to (2.45 ± 0.14) mSv.y-1 with average value of (0.98 ± 0.18) mSv.y-1. The average value of Lung Cancer Case (LCC) per year and per million persons was found at 17.62. The average radon concentration is lower than the WHO, UNSCEAR 2000, and GSR Part N°.3 Public limit value, however, its contribution to the total exposition to the population is significant. It has been found that all the obtained results during this works vary across regions. The Region of Vakinankaratra represents the highest effective average value of annual high effective dose and radon concentration due to high uranium potential of this region. Analanjirofo and Antsinanana regions represent the lowest annual effective dose and radon concentration due to the abundance of Th-232 concentration than Uranium in these regions.
Abstract: Radon is the radioactive gas naturally present in the environment produced by natural radioactive decay of uranium-238. It is uncolored and inodorous and present in outdoor air as well as in dwelling spaces. In nine (09) regions of Madagascar, radon study was carried out for indoor radon concentration measurement in 62 dwellings spread. The aim of ...
Show More
-
Research Article
Determination of 238U and 232Th Levels in Well Water and Associated Radiological Hazards in the Municipality of Ivato Airport, Madagascar
Issue:
Volume 13, Issue 2, April 2025
Pages:
38-45
Received:
22 March 2025
Accepted:
31 March 2025
Published:
27 April 2025
DOI:
10.11648/j.ajpa.20251302.14
Downloads:
Views:
Abstract: Groundwater always contains uranium and thorium but with varying concentrations depending on the area geological formation. Long-term ingestion of water containing high natural radioactivity levels could cause diverse effects to human health. This is the reason why the study of two radionuclides 238U and 232Th was conducted in the well water in the Municipality of Ivato airport, Madagascar. Measurements have been performed by high-resolution gamma spectrometry system with coaxial HPGe detector to determine the specific activities of two radionuclides in ten samples. The samples were put into 1 litre Marinelli beakers, sealed hermetically and stored for three weeks to reach secular equilibrium between 226Ra and its daughters before analyses. Results obtained showed that the specific activities vary from (4.08 ± 0.52) Bq.kg-1 to (4.48 ± 0.70) Bq.kg-1 with an average value of (4.36 ± 0.12) Bq.kg-1 and from (4.40 ± 0.42) Bq.kg-1 to (4.80 ± 0.73) Bq.kg-1 with an average value of (4.61 ± 0.12) Bq.kg-1 respectively. The effective annual dose rate due to ingestion were also determined, and compared to the worldwide average values, the WHO reference value and the permissible limit value of public. Statistical studies of the data were carried out to understand the behavior of uranium and thorium elements in these waters. Generally, radionuclides present in well water have normal levels of radioactivity. This means that these levels do not present any radiological risks to the local population.
Abstract: Groundwater always contains uranium and thorium but with varying concentrations depending on the area geological formation. Long-term ingestion of water containing high natural radioactivity levels could cause diverse effects to human health. This is the reason why the study of two radionuclides 238U and 232Th was conducted in the well water in the...
Show More
