scholarly journals A Systematic Review of Permeable Pavements and Their Unbound Material Properties in Comparison to Traditional Subbase Materials

2021 ◽  
Vol 6 (12) ◽  
pp. 179
Author(s):  
Dansani Vasanthan Muttuvelu ◽  
Erik Kjems

This paper is a literature review focused on permeable pavements and especially the permeable subbase material. Run-off water from the surface is traditionally let through a drainage system, and the roads are kept dry. Due to climate changes, heavy precipitation and high-intensity rainfalls are putting pressure on the infrastructure. Traditionally, water in subbase materials reduces the resilient E-moduli and the lifespan of the pavement design. Studies show that increasing saturation reduces the bearing capacity of a traditional subbase material. Unbound materials with highly grained fines and high moisture content have higher tendency to show reduced resilient E-moduli. One study was found where the E-moduli of five different coarse grained aggregates used in permeable pavements were examined through a triaxial test. It was found that the E-moduli varied from 110–371 MPa. Other studies examining the E-moduli of permeable subbases based on moisture content were not found. However, this paper discusses different experiences regarding the bearing capacity of traditional vs. permeable subbase materials. It also covers a discussion and an analysis of missing research areas that needs to be investigated for further knowledge about the usage of permeable pavements in areas with a risk of flooding.

2017 ◽  
Vol 12 (3) ◽  
pp. 400 ◽  
Author(s):  
Valdiney Cambuy Siqueira ◽  
Flávio Meira Borém ◽  
Guilherme Euripedes Alves ◽  
Eder Pedroza Isquierdo ◽  
Afonso Celso Ferreira Pinto ◽  
...  

Objetivou-se, com o presente trabalho, propor um novo método de processamento e secagem, assim como avaliar o comportamento dos grãos submetidos a este processo, por meio da taxa de redução de água e do ajuste de diferentes modelos matemáticos aos dados experimentais da secagem. Os frutos colhidos no estágio maduro foram divididos em três lotes. O primeiro foi seco continuamente à temperatura de 40±1 °C. O segundo consiste na secagem do café natural até os teores de água de 0,56±0,02, 0,41±0,02, 0,28±0,02 e 0,20±0,02 decimal (base seca, b.s.), seguido de beneficiamento e secagem contínua nas temperaturas de 35±1 ºC e 40±1 ºC. O terceiro lote correspondeu à secagem contínua do café descascado e desmucilado na temperatura de 40±1 °C. Em todos os lotes, a secagem foi encerrada quando os grãos atingiram o teor de água de 0,12±0,05 (b.s.). Aos dados experimentais da secagem foram ajustados dez modelos matemáticos utilizados para representação da secagem dos produtos agrícolas. Além da representação da cinética de secagem foi avaliada a taxa de redução de água dos grãos. Conclui-se que a taxa de redução de água é maior para a temperatura de secagem de 40±1 °C, especialmente para maiores teores de água. O tempo total de secagem do café beneficiado com alto teor de água é expressivamente reduzido, quando comparado ao tempo de secagem completa do café natural. O modelo de Midilli descreve satisfatoriamente a cinética de secagem do café beneficiado.


1965 ◽  
Vol 7 (3) ◽  
pp. 385-387 ◽  
Author(s):  
T. R. Preston ◽  
H. B. Bowers ◽  
N. A. MacLeod ◽  
Euphemia B. Phillip

The use of barley for intensive beef production, as described by Preston, Aitken, Whitelaw, Macdearmid, MacLeod and Philip (1963) is now a well established practice, but one of the hazards of this feeding system is bloat. There is evidence that the risk of this condition is accentuated if the barley husk is broken down too finely as happens if the grain is ground (Preston, Macdearmid and MacLeod, 1963; Preston, 1964). It was therefore recommended that barley should be processed in a roller mill and that the moisture content should be at least 16% (Preston, 1963), for if the grain is drier than this it is difficult to prevent excessive shattering and destruction of the husk. Suitable containers, which can be sealed in order to ensure anaerobic conditions and so overcome the problem of storing damp grain (greater than 16% moisture) have additional advantages at harvest since they can be filled quickly and easily. The purpose of this experiment was to evaluate the nutritive value of barley stored under these conditions.


2014 ◽  
Vol 124 ◽  
pp. 267-274 ◽  
Author(s):  
Seung-Hyun Moon ◽  
In-Soo Ryu ◽  
Seung-Jae Lee ◽  
Tae-In Ohm

2020 ◽  
pp. 303-303
Author(s):  
Yongli Xiao ◽  
Hualin Wang ◽  
Shengan Deng ◽  
Fuyong Su ◽  
Zhi Wen

High-temperature metallurgical slag (temperature, > 1450 ?C) and high-moisture sludge (moisture content, > 80 wt%) are common wastes with huge outputs. Many problems, such as high cost, low level of harmlessness, and low efficiency, are encountered in current treatment methods. If these wastes can be recycled, they can be valuable secondary resources. Therefore, using the drum apparatuses to treat these two kinds of wastes is proposed. The process uses waste heat of slag to dry sludge with high moisture content and is a kind of alternative circulation treatment technology in which steel balls are used as ball milling media and intermediate heat carriers. Besides, this technology can break up slag or sludge in real time, thereby ensuring high heat or mass transfer rate. This study presents an experimental investigation of the dynamic drying process of wet sludge mixed with hot steel balls in a rotary drum. The relationship of operation parameters (including sludge moisture content, sludge treatment mass, steel ball diameter, and rotary speed of drum) and drying effect is obtained. There are three kinds of final drying results: completely dried to powder, few sludge agglomerations, and sludge-to-wall adhesion. If the operating parameters are set well, the sludge could be efficiently and completely dried and eventually in powder form.


2020 ◽  
Vol 67 (2) ◽  
pp. 73-77
Author(s):  
Zarife Bajraktari-Gashi ◽  
Muharrem Zabeli ◽  
Behram Halilaj

AbstractDuring 1984–1997, the ferronickel plant in Drenas used iron-nickel ore from the mines of the Republic of Kosovo: Glavica and Çikatove (Dushkaje and Suke) mines. However, during the years 2007–2017, when the plant started operating from the cessation of production, which was from 1998 to 2007, some types of iron-nickel ores from different countries began to be used, starting from iron-nickel ores from Kosovo, iron-nickel ores from Albania, ores from Indonesia, ores from the Philippines, ores from Guatemala, ores from Turkey and ores from Macedonia. The ore composition, however, is mainly oxide-laterite ore. Iron-nickel ores in the plant are characterised by high moisture content, a very important factor influencing the process of scraping the charge in rotary kilns and presenting in general. Among the iron-nickel ore used in the ferronickel plant, the ores from Albania are characterised due to their low moisture content when compared with the other ores as well as the high content of iron oxides, which affect the temperature rise inside the furnaces, as the iron ores play an important role in the pre-casting process in rotary kilns.


Author(s):  
Hannah Nyambara Ngugi ◽  
Stanley Shitote ◽  
Nathaniel Ambassah ◽  
Victoria Okumu ◽  
John Thuo

2014 ◽  
Vol 23 (2) ◽  
pp. 89-95
Author(s):  
J. A. Okhuoya ◽  
S. O. Itaman

In a fungal suryey of sawn timbers in scattared localities in Benin City, fungal species isolated were mainly members of <i>Hyphomycetes</i>, with few <i>Ascomycetes</i> and<i> Basidiomycetes</i>. Cellulolytic abilities of isolates were determined and found to be highest in a basidiomycete, <i>Pleurotus ostreatus</i>. The high incidence of these isolates was traced to the poor ventillation in the shades where the timbers arę sold and the high moisture content of timber before display for sale.


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