Environmental effects of road pavements stabilized with Class F fly ash

Published ArticleFly Ash is a residue generated by coal combustion and abundantly available, but due to potentially toxic elements found in Fly Ash, is considered harmful to the environment. The objective of this study is to evaluate the environmental effects of fly ash used as a stabilization agent in road pavement construction. Using laboratory-testing specimens of fly ashes namely, Kendal Dump Ash, Durapozz and Pozzfill, stabilized with classified G5 material and 1% AFRISAM and LAFARGE cement respectively and leach testing done to evaluate chemical leach properties over time and the harmful effects it has on the environment. Laboratory leaching sample results have indicated that Fly Ash constituents exhibit limited mobility. The study revealed that Fly Ash is an environmental option and has engineering advantages when used properly for soil stabilization techniques

South Africa Class F Fly Ash for roads : physical and chemical analysis

Published ArticleFly Ash is a by-product at thermal power stations, also otherwise known as residues of fine particles that rise with flue gases. An industrial by-product may be inferior to the traditional materials used construction applications, but, the lower the cost of these inferior materials make it an attractive alternative if adequate performance can be achieved. The objective of this study is to evaluate the chemical and physical effectiveness of self-cementing fly ashes derived from thermal power stations for construction applications with combined standards. Using laboratory testing specimens, suitable types of Fly Ashes namely: Kendal Dump Ash, Durapozz and Pozzfill, were tested to the required standards to evaluate the potential properties. All three Fly Ashes have been classified as a Class F Fly Ash, which requires a cementing agent for reactions to take place and for early strength gains in the early stages of the reaction processes. The Fly Ashes conformed to the combination of standards and have shown that the proper reactions will take place and will continue over period of time. The use of fly ash is accepted worldwide due to saving in cement, consuming industrial waste and making durable materials, especially due to improvement in the quality fly ash products

Observation of Gravitational Waves from the Coalescence of a 2.5−4.5 M⊙2.5-4.5~M_\odot Compact Object and a Neutron Star

International audienceWe report the observation of a coalescing compact binary with component masses $2.5-4.5~M_\odot$ and $1.2-2.0~M_\odot$ (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO-Virgo-KAGRA detector network on 2023 May 29 by the LIGO Livingston Observatory. The primary component of the source has a mass less than $5~M_\odot$ at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We estimate a merger rate density of $55^{+127}_{-47}~\text{Gpc}^{-3}\,\text{yr}^{-1}$ for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star-black hole merger, GW230529_181500-like sources constitute about 60% of the total merger rate inferred for neutron star-black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star-black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap

Observation of Gravitational Waves from the Coalescence of a 2.5−4.5 M⊙2.5-4.5~M_\odot Compact Object and a Neutron Star

International audienceWe report the observation of a coalescing compact binary with component masses $2.5-4.5~M_\odot$ and $1.2-2.0~M_\odot$ (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO-Virgo-KAGRA detector network on 2023 May 29 by the LIGO Livingston Observatory. The primary component of the source has a mass less than $5~M_\odot$ at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We estimate a merger rate density of $55^{+127}_{-47}~\text{Gpc}^{-3}\,\text{yr}^{-1}$ for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star-black hole merger, GW230529_181500-like sources constitute about 60% of the total merger rate inferred for neutron star-black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star-black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap