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When it reacts with concrete, it causes the slab to expand, lifting, distorting and cracking as well as exerting a pressure onto the surrounding walls which can cause movements significantly weakening the structure. Some infill materials frequently encountered in building fondations and causing sulfate attack are the following: [2] Red Ash
Biogenic sulfide corrosion is a bacterially mediated process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid that attacks concrete and steel within wastewater environments. The hydrogen sulfide gas is biochemically oxidized in the presence of moisture to form sulfuric acid.
Degraded concrete and rusted, exposed reinforcement bar (rebar) on Welland River bridge of the Queen Elizabeth Way in Niagara Falls, Ontario. Concrete degradation may have many different causes. Concrete is mostly damaged by the corrosion of reinforcement bars due to the carbonatation of hardened cement paste or chloride attack under wet ...
Corrosion deposits should not be confused with fouling deposits formed by ex-situ generated corrosion products. Corrosion deposits will normally have composition related to the composition of the substrate. Also, the geometry of the metal-oxide and oxide-fluid interfaces may allow practical distinction between the corrosion and fouling deposits.
The simplest recommended technique is to identify any porosity of the coating as revealed by the presence of surface spots. These surface spots form where the environmental sulfur has penetrated and reacted with the base metal, producing a metal sulfide. Chalcocite, copper (I) sulfide is dark-grey to black. Silver (I) sulfide is also grey-black.
Sedimentary exhalative deposits (SEDEX or SedEx deposits) are zinc-lead deposits originally interpreted to have been formed by discharge of metal-bearing basinal fluids onto the seafloor resulting in the precipitation of mainly stratiform ore, often with thin laminations of sulfide minerals.
Volcanogenic massive sulfide ore deposits, also known as VMS ore deposits, are a type of metal sulfide ore deposit, mainly copper-zinc which are associated with and produced by volcanic-associated hydrothermal events in submarine environments. [2] [3] [4] These deposits are also sometimes called volcanic-hosted massive sulfide (VHMS) deposits
ASTM C1293: "Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction". It is a long-term confirmation test (1 or 2 years) at 38 °C in a water-saturated moist atmosphere (inside a thermostated oven) with concrete prisms containing the aggregates to be characterised mixed with a high-alkali ...