Search results
Results from the WOW.Com Content Network
Corrosion may occur where stale sewage generates hydrogen sulfide gas into an atmosphere containing oxygen gas and high relative humidity. There must be an underlying anaerobic aquatic habitat containing sulfates and an overlying aerobic aquatic habitat separated by a gas phase containing both oxygen and hydrogen sulfide at concentrations in excess of 2 ppm.
In lining or coating applications using ECTFE, permeability of certain small molecules determines the lifetime of anti-corrosion protection. Small molecules such as H 2 O , O 2 , Cl 2 , H 2 S , HCl , HF , HBr , N 2 , H 2 , and CH 3 OH are relatively mobile in the polymer matrix and lead to measurable effects.
The corrosion resistance and low permeability of polymer concrete allows it to be used in swimming pools, sewer structure applications, drainage channels, electrolytic cells for base metal recovery, and other structures that contain liquids or corrosive chemicals. It is especially suited to the construction and rehabilitation of manholes due to ...
Example of flat piece of concrete having dislodged with corroded rebar underneath, Welland River bridge across Queen Elizabeth Way in Niagara Falls, Ontario. The expansion of the corrosion products (iron oxides) of carbon steel reinforcement structures may induce internal mechanical stress (tensile stress) that cause the formation of cracks and disrupt the concrete structure.
[5] [6] The action of either a tensile stress or a corrosive liquid alone would not be enough to cause failure, but in ESC the initiation and growth of a crack is caused by the combined action of the stress and a corrosive environmental liquid. These corrosive environmental liquids are called 'secondary chemical agents', are often organic, and ...
A fairly well-defined reaction front can often be observed in thin sections; ahead of the front the concrete is normal, or near normal. Behind the reaction front, the composition and the microstructure of concrete are modified. These changes may vary in type or severity but commonly include: Extensive cracking; Expansion
Barrier release agents prevent adhesion by the development of a physical film or barrier between the forming surface and the concrete. Reactive release agents are chemically active and work by the process of a chemical reaction between the release agent and the free limes available in fresh concrete. A soapy film is created which prevents adhesion.
Classification of fluids with shear stress as a function of shear rate: Pseudoplastic, Bingham plastic and Bingham pseudoplastic all show reduction in apparent viscosity with increasing shear rate. In rheology , shear thinning is the non-Newtonian behavior of fluids whose viscosity decreases under shear strain .