Search results
Results From The WOW.Com Content Network
The attack arises from soils containing SO2−. 4 ions, such as MgSO 4 or Na 2 SO 4 soluble and hygroscopic salts. The tricalcium aluminate (C 3 A) hydrates first interact with sulfate ions to form ettringite (AFt). Ettringite crystallizes into small acicular needles slowly growing in the concrete pores. Once the pores are completely filled ...
When atmospheric carbon dioxide (CO 2), or carbonate ions (HCO − 3, CO 2− 3 dissolved in water) diffuse into concrete from its external surface, they react with calcium hydroxide (portlandite, Ca(OH) 2) and the pH of the concrete pore water progressively decreases from 13.5 – 12.5 to 8.5 (pH of water in equilibrium with calcite).
e. Hydrogen embrittlement (HE), also known as hydrogen-assisted cracking or hydrogen-induced cracking (HIC), is a reduction in the ductility of a metal due to absorbed hydrogen. Hydrogen atoms are small and can permeate solid metals. Once absorbed, hydrogen lowers the stress required for cracks in the metal to initiate and propagate, resulting ...
Zinc sacrificial anode (rounded object) screwed to the underside of the hull of a small boat. Cathodic protection (CP; / kæˈθɒdɪk / ⓘ) is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. [1] A simple method of protection connects the metal to be protected to a more easily ...
Most coatings have four basic components. These are the resin, solvent, pigment and additive systems [5] but the resin or binder is the key ingredient. Continuing environmental legislation in many countries along with geopolitics such as oil production are ensuring that chemists are increasingly turning to waterborne technology for paint/coatings and since resins or binders are the most ...
A water-based pipe coating is an environmentally friendly coating that is applied to the inner and outer surfaces of ductile iron pipe. The coating serves to protect the water supply lines from corrosion whether from the outside or the inside. It also serves to protect the drinking water from contamination. The coating is an emulsion ...
Calcium silicate hydrates (CSH or C-S-H) are the main products of the hydration of Portland cement and are primarily responsible for the strength of cement-based materials. [1] They are the main binding phase (the "glue") in most concrete. Only well defined and rare natural crystalline minerals can be abbreviated as CSH while extremely variable ...
The concentration of hydrogen ions and pH are inversely proportional; in an aqueous solution, an increased concentration of hydrogen ions yields a low pH, and subsequently, an acidic product. By definition, an acid is an ion or molecule that can donate a proton, and when introduced to a solution it will react with water molecules (H 2 O) to ...