Imagine a city that could devour the very pollution that it creates. Such was the scenario envisioned by scientists in the Netherlands, who have found that using specially treated pavement on city streets can cut air pollution nearly in half. The researchers from Eindhoven University of Technology installed concrete paving which included titanium dioxide –…
Lead paint without cracks, fragmentation or deterioration is not likely to be considered hazardous for human health. However, if lead paint has been used in the homes then extra care is essential to avoid unnecessary exposure to lead dust. The door frames and stair railings may have lead paint. Basics Of Lead Paint Paint is a material…
Paint removal is a technique that requires special skill to prevent damage to the surfaces from where paint is removed. The traditional methods for paint removal require a lot of skill and time. Infrared heat gun may be used for paint removal that is much more fast, reliable, and safe. Infra Red Paint Removal Techniques The infra…
Paints are used to ensure protection of the buildings from harmful weather effects, including rain, heat, and winds, and also to improve the surface finish. The useful life of structures is influenced by the application of paints that are available in several varieties of colors and textures. Fundamentals Of Paint Paint is in a liquid state and is transformed…
Autogenous healing is common in underground drainage pipes because of the presence of water on either side of the pipes. The non-moving cracks in concrete pipes are sealed by calcium carbonate crystals from carbon dioxide in air and calcium hydroxide in concrete in the process called autogenous healing. The healed cracks are impermeable and behave…
For carbon dioxide attack, carbon dioxide dissolves in water to form a weak acid called carbonic acid. It would dissolve the cement matrix. However, the amount of carbon dioxide from the atmosphere is usually not sufficient to cause harm to concrete structures until additional source of carbon dioxide is available (e.g. decaying vegetable matter). Carbonation…
Carbon dioxide and chloride present in the concrete are inert in the absence of the water and oxygen. Carbon dioxide in the pore of the concrete reacts with water to form carbonic acids which reduce the pH of the concrete. In the absence of water carbon dioxide is in active. Chloride in concrete is also…
The chloride ion attacks the passive layer although in this case (unlike carbonation) there is no overall drop in pH. Chlorides act as catalysts to corrosion. They are not consumed in the process but help to break down the passive layer of oxide on the steel and allow the corrosion process to proceed quickly as shown in…
Carbonation is the result of the interaction of carbon dioxide gas in the atmosphere with the alkaline hydroxides in the concrete. Like many other gases carbon dioxide dissolves in water to form an acid. Unlike most other acids the carbonic acid does not attack the cement paste, but just neutralizes the alkalinity in the pore…
Abstract Steel gets oxidise (corrosion) in the present of oxygen and water. Even present of oxygen in the concrete pore will not cause a corrosion at high alkaline environment. Concrete contains microscopic pores which contain high concentrations of soluble calcium, sodium and potassium oxides, this creates alkaline condition of pH 12–13. The alkaline condition leads…