Water Permeability Resistance Research Articles

Study on water permeability, shear and pull-off performance of waterproof bonding layer for highway bridge

The performance of waterproof bonding layer directly effects the durability of the highway bridge. Water permeability, shear strength and tension strength are three main indicators evaluating the waterproof bonding layer. In this research, three waterproof bonding materials including SBS modified asphalt, SBR modified asphalt emulsion and second order reaction waterproof material were selected. The water permeability, shear strength and pull-off strength were tested. The effect of different temperature and different contents were analyzed. Results show that: the water permeability resistance of waterproof bonding layer ranked as follows: SBS modified asphalt>Second order reaction waterproof material>SBR modified asphalt emulsion. Compared to SBR modified asphalt emulsion and second order reaction waterproof material, SBS modified asphalt has a better shear resistance. Three waterproof materials used in this research all have temperature sensitivity. Their shear strength and tension strength decrease dramatically with temperature increasing.

Surface modified used rubber tyre aggregates: effect on recycled concrete performance

Although research has found that using rubber in concrete will enhance its resilience and reduce its density, the significant loss of strength owing to lack of bonding has remained unresolved. This study considers how to minimise the loss of strength of concrete with used rubber tyre crumb aggregates and investigates the improvement of water permeability resistance that may consequentially develop. A surface of rubber crumb was modified by soaking in the saturated sodium hydroxide solution or silane coupling agent (SCA) before using. Up to 20% of natural fine aggregate was volumetrically replaced with treated rubber crumb. Experimental results show higher compressive and flexural strengths, Young's modulus and water permeability resistance from the samples with SCA-treated rubber than with as-received or sodium-hydroxide-treated rubber. X-ray diffraction pattern analyses indicate almost no change in crystalline phase for the rubber surface modification. Microscopic inspections show an enhanced rubber-matrix adhesion with the use of SCA. Results of mercury intrusion porosimetry reveal that concrete with SCA-treated rubber has a similar pore size distribution to the other three mixes, but achieves the lowest porosity and highest tortuosity, resulting in the best water permeability resistance. A brief cost analysis suggests that this method of surface modification is economically viable.

Strength and durability characteristics of latex-modified jute/macro-synthetic hybrid fibre-reinforced concrete

The effects of latex on the strength characteristics and durability of hybrid fibre-reinforced concrete were evaluated. The hybrid fibre was composed of 0·2 vol.-% natural jute fibre and 0·05 vol.-% macro-synthetic fibre. Latex was added at 0, 5, 10 and 15 wt-% of the cement weight. The compressive strength, flexural strength, chloride ion permeability, abrasion resistance and impact resistance were measured. The strength, water permeability resistance, abrasion resistance and impact resistance increased with the latex content owing to the improvement in fibre dispersity. Additionally, the adhesion between the cement materials improved with the formation of a latex film. Increasing the latex content from 5 to 10% greatly improved the performance of the hybrid fibre-reinforced concrete, because the natural jute and macro-synthetic fibres effectively suppressed the generation and growth of cracks within the concrete.

Green Bambusa Arundinacea leaves extract as a sustainable corrosion inhibitor in steel reinforced concrete

The experimental studies carried out on water permeability resistance and microstructure of reinforced concrete treated with Bambusa arundinacea as green corrosion inhibitor, are reported in this article. The effectiveness of Bambusa arundinacea as green corrosion inhibitor was compared with that of calcium nitrite and ethanolamine inhibitors. Concrete mix was designed for a compressive strength of 30 MPa with a 0.45 water-to-cement ratio (W/C) which was chloride contaminated. Inhibitors addition was 2% by weight of cement. The specimens were subjected to various tests, namely; compressive strength test, durability (permeability using initial surface absorption test (ISAT) and field emission scanning electron microscopy (FESEM)) for 360 days exposure. Water absorption values of steel reinforced concrete in the presence of Bambusa arundinacea inhibitor were generally less than 0.25, 0.17, 0.1 and 0.07 mL/m2 s after 10 min, 30 min, 1 h and 2 h, i.e., as required by ISAT standard for low permeability concrete. This might possibly be due to the presence of residual alkalinity of potassium hydroxide (KOH) in the concrete. KOH is adequate for passivation and reduction of permeability, which serves as a chemical water barrier or hydrophobic agent that stabilizes calcium silicate hydrates.

Sputter deposition of semicrystalline tin dioxide films

Tin dioxide is emerging as an important material for use in copper indium gallium diselenide based solar cells. Amorphous tin dioxide may be used as a glass overlayer for covering the entire device and protecting it against water permeation. Tin dioxide is also a viable semiconductor candidate to replace the wide band gap zinc oxide window layer to improve the long-term device reliability. The film properties required by these two applications are different. Amorphous films have superior water permeation resistance while polycrystalline films generally have better charge carrier transport properties. Thus, it is important to understand how to tune the structure of tin dioxide films between amorphous and polycrystalline. Using X-ray diffraction (XRD) and Hall-effect measurements, we have studied the structure and electrical properties of tin dioxide films deposited by magnetron sputtering as a function of deposition temperature, sputtering power, feed gas composition and film thickness. Films deposited at room temperature are semicrystalline with nanometer size SnO2 crystals embedded in an amorphous matrix. Film crystallinity increases with deposition temperature. When the films are crystalline, the X-ray diffraction intensity pattern is different than that of the powder diffraction pattern indicating that the films are textured with (101) and (211) directions oriented parallel to the surface normal. This texturing is observed on a variety of substrates including soda–lime glass (SLG), Mo-coated soda–lime glass and (100) silicon. Addition of oxygen to the sputtering gas, argon, increases the crystallinity and changes the orientation of the tin dioxide grains: (110) XRD intensity increases relative to the (101) and (211) diffraction peaks and this effect is observed both on Mo-coated SLG and (100) silicon wafers. Films with resistivities ranging between 8mΩ cm and 800mΩ cm could be deposited. The films are n-type with carrier concentrations in the 3×1018cm−3 to 3×1020cm−3 range. Carrier concentration decreases when the oxygen concentration in the feed gas is above 5%. Electron mobilities range from 1 to 7cm2/Vs and increase with increasing film thickness, oxygen addition to the feed gas and film crystallinity. Electron mobilities in the 1–3cm2/Vs range can be obtained even in semicrystalline films. Initial deposition rates range from 4nm/min at low sputtering power to 11nm/min at higher powers. However, deposition rate decreases with deposition time by as much as 30%.

Water and Air Permeability for Polyester Fabrics

The water permeability was studied in comparison with the air permeability for a series of polyester fabrics. The experimental apparatus for the water permeability measurement is composed of a vertical cylinder at the bottom of which a specimen is attached. The water filled in the cylinder flows by its weight through the specimen. The water flow was measured as a function of time in the water pressure range from about 6.63 to 2.22 kPa. The water pressure drop by the specimen, obtained after correcting the water pressure drop inherent to the apparatus, changed in proportion to the water flow rate. The proportional coefficient of the pressure drop against the flow rate was defined as the water permeation resistance Rw. The air flowresistance Ra was measured by separate experiments. The water flow resistance Rw was proportional to the flow resistance of air Ra, and the flow resistance ratio Rw/Ra was 71.1. According to the Darcy's law the flow resistance ratio Rw/Ra equals the ratio of the water viscosity ηw to the air viscosity na. The value of the viscosity ratio nw / na , which is calculated with the viscosity values of 1.00 mPa*s for water and 18.1 uPa*s for air, is 55.2. This value of viscosity ratio nw / na agrees reasonably with the value of flow resistance ratio Rw/Ra obtained experimentally.

Air and water permeation resistance across dust cakes on filters—effects of particle polydispersity and shape factor

The permeability of dust cakes on a filter for both air and water was studied theoretically and experimentally. The study investigated, in particular, the effects of particle polydispersity and shape factor on the permeability. In the experimental study, both air and water permeability tests were carried out on six different types of powders including monodisperse spheres and various polydisperse non-spherical particles. Using the parameters derived from a theory that took into account the effects of the particle polydispersity and particle shape, all the collected data were found to correlate well with the dust cake porosity ranging from 0.3 to 0.8 for both air and water permeation. The results suggest that the well-known Kozeny–Carman equation is not applicable for fluid permeation through particle layers having wide powder size distributions or irregular shape. With the proposed correlation, the permeation resistance of gas and liquid across powder layers consisting of non-spherical and polydisperse particles can be quantified. The correlation is useful for the design of filtration devices and the determination of operating conditions in filtration processes for both dust aerosols and colloidal suspensions.

Evaluation of jacket materials and configurations and effect of moisture absorbing materials on preventing water tree growth in power cables

Polymer insulated medium voltage cables have experienced premature failures in-service, due in large part to water treeing. Research has shown that the initiation sites of these water trees are often located where there are stress enhancements at the insulation/semiconducting shield interface and where water soluble contaminants permeate into the insulation. Material suppliers, cable manufacturers and users have introduced improved materials and cable designs as well as processing, manufacturing, transport, storage, and installation techniques that minimize contamination. Despite these advancements, gradual contamination can still occur due to the diffusion of ground water into the insulation. In fact, certain contaminants that are carried through the semiconductor/insulation shield interfaces tend to promote water tree growth. Manufacturers are now beginning to recognise this problem and have suggested the use of moisture resistant cables with jackets made of PVC, polyethylene or metal/polymer laminates along with underjacket water absorbing materials. This paper discusses the effectiveness of different jackets and materials and presents data on the effectiveness of water absorbing materials in delaying water permeation into the insulation. A simple and efficient cable-cell technique was developed which monitored the effectiveness of complete cable designs, by measuring the long-term water permeation resistance of short lengths of distribution class cables.