Search

With the ingrowing awareness of environmental and energetic issues, earthen materials offer significant ecological and economic advantages. In Algeria, the Ksour (earthen buildings) remains the only witness to this type of construction. This research aims to contribute to extending the knowledge of these types of constructions to provide a proper intervention for their restoration and also help to produce adobes with good resistance and durability to reduce the renewal of plasters, which is pricey and time-consuming in the aim of declining the cost of housing, especially in rural areas. To achieve this, different mixtures of adobes were studied in order to test the effects of quicklime, cement and date palm fibers on their physical, mechanical and water resistance properties. The main results obtained showed that the addition of quicklime and cement in different combinations in adobes improves the mechanical properties. The inclusion of the DPF up to 0.5% in untreated adobes and 5% cement-stabilized adobes enhance the mechanical strengths, whereas in adobes stabilized with quicklime it leads to a decrease in their strength. The addition of cement and quicklime increases significantly the water resistance of the adobes, while the inclusion of fibers has an adverse effect. [ABSTRACT FROM AUTHOR]

The study of the erosion activity of cavitation is of considerable interest for clarifying the mechanism of the effect of cavitation on biological tissues and cells. This paper proposes an improved technique for assessing the erosion activity of acoustic cavitation. The results of testing this technique in relation to the problem of studying the distribution of erosion activity in the cavitation region, generated by a radiator with a rod waveguide, are presented. The experiments were carried out using a submersible emitter with a resonant frequency of 32 kHz. It was found that erosion activity rapidly decreases with distance from the emitter and depends on the distance to the emitter L as 1/L3 when the diameter of the emitter is less than or of the order of the wavelength in the used liquid. It was shown that there is a correlation between the erosion activity of cavitation and the readings of the cavitometer with the output signal being the integral intensity of the highfrequency component of the cavitation noise in the frequency range up to 10 MHz. Piezoelectric sensors were used to register cavitation noise. In particular, in liquids characterized by a higher level of erosion activity, the output signal of the cavitometer is also higher. In this case, the readings of the cavitometer change depending on the distance to the radiator as 1/L. Based on the data obtained, a method is proposed for assessing the erosion activity of cavitation by the magnitude of the intensity of cavitation noise in a cube. It is shown that this parameter is linearly related to the results of measurements of the erosional activity of cavitation. The results obtained will be used in the development of a specialized cavitometer designed to assess the erosion activity of cavitation during in vitro studies of the effect of ultrasound on cells.

Elastomers and plastics are widely used as the materials for handling abrasive/erosive slurries because of their wear resistance, toughness, corrosion resistance and light weight. In this study, slurry jet erosion, Coriolis slurry scouring erosion and large particle slurry erosion are used to characterize the erosion resistance of selected elastomers and plastics, including two natural rubbers, a neoprene rubber, a polyurethane and three types of polyethylene, at different test conditions. The wear rates and wear modes of the tested materials are presented and the relationships between the erosion resistance of these materials and their mechanical properties are discussed. Suitable applications of these materials in slurry transport are also recommended. • Elastomers have excellent erosion resistance because of their excellent resilience to absorb deformation elastically. • Plastics have good erosion resistance because of their moderate resilience to absorb deformation elastically. • Elastomers and plastics are suitable for resisting erosion attacks by small and rounded or semi-rounded particles. • Elastomers and plastics have displayed increased erosion resistance at elevated temperature. [ABSTRACT FROM AUTHOR]

Physical processes occurring after placing the filter diaphragm in cavitation medium created by ultrasonic wave, the intensity of which exceeds the threshold of cavitation conditions have been studied. The behavior of cavitation bubble and pollutant particle in ultrasonic field are analyzed making it possible to build a mathematical model of the water filtration process in ultrasonic medium. The impact of different factors on the cavitation intensity was also studied. Experiments were conducted to investigate the impact of static pressure on the intensity of cavitation erosion by using the erosion test method. Aluminum foil was used as a test material. Experiments were conducted in the cavitation chamber at the low and increased values of static pressure with respect to its atmospheric value. [ABSTRACT FROM AUTHOR]

SUMMARY Internal erosion (IE) affects the stability of natural and reinforced materials by causing instability within their granular structure. The dislodgement and transport of eroded particles affect both the particulate concentration of eroding fluid and the pore network of eroded material. In this study, we examined these modifications using a transport model with a finite element code. First, IE tests on chemically reinforced sand columns were performed to obtain information about eroded material loss of mass, particulate concentration of effluent, porosity and permeability modifications, and existing IE stages. Second, based on experimental results, a mathematical one-dimensional model has been formulated to monitor the evolution and spatial distribution of erodible solids, fluidized particles, porosity, permeability, and seepage stresses. The model consists of a set of coupled nonlinear differential equations solved in sequence. It provides valuable information about the extent and the dynamics of structural changes, which can be used to estimate an IE time for the hydraulic work to reach failure. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The physical characteristics of sediments were measured from transects in the Minho, Lima, Cávado, and Ave estuaries in the northern part of Portugal. The variables investigated were: chemical composition, particle size, water content, salinity, temperature, and pH. In a miniflume used to measure erodibility, erosion tests were filmed with a high speed camera and the rheological characteristics of overlaying fluid layer were measured using a rheometer. Because the physical sediment characteristics are related to its erosion, the physical characterization and the erodability were correlated. The influence of the season and sampling site on the sediment properties were assessed for the Cávado estuary. Large differences were found in the physical characterization between the four estuaries, namely in particle size, water content, and chemical composition, and these were important in determining the stability of sediments. Shortterm changes in weather conditions prior to sampling and site-to-site variability were found to have more significant effects on the sediment physical properties than seasonal changes. [ABSTRACT FROM AUTHOR]

Surface material loss due to erosive wear is responsible for the increased cost of maintenance and downtime in industries. Hence, hardfacing is one of the most valuable and effective techniques employed to improve the wear resistance of heavy-duty components. The present paper investigates the microstructural and erosive wear characteristics of a hypereutectic high-chromium cast iron, considering the erosion resistance, resulting from the impact of micro-sized particles, of both as-received and heat-treated conditions. Micro-sized particles involve the erosion-resistant characteristics of carbide and matrix, contemporary. Due to this, the enhancement of the matrix strength could improve the mechanical support to withstand cracking deformation and spalling. Accordingly, the effect of a destabilization heat treatment on the microstructure was firstly investigated by hardness tests, X-ray diffraction analyses, optical and scanning electron microscopy. Specifically designed erosive tests were carried out using a raw meal powder at an impingement angle of 90°. The resulting superior wear resistance of the heat-treated samples was relayed on the improved matrix microstructure: consistent with the observed eroded surfaces, the reduced matrix/carbides hardness difference of the heat-treated material is pivotal in enhancing the erosion resistance of the hardfacing. The present results contribute to a better understanding of the microstructure–property relationships concerning the erosive wear resistance. [ABSTRACT FROM AUTHOR]