H2S is a gas that seriously degrades all concrete and pointing mortar in brickwork.
H2S is an acidic gas that is often formed in the sewage network and other process systems. The chemical attack is referred to as biogenous sulphuric acid corrosion with the live bacteria excreting sulphuric acid in the gas zone above the water line of the process water to such an extent that in unvented environments PH values of PH1 are often recorded causing extensive damage to the concrete surface as it simply degrades the cement within the matrix turning it to a ‘mushy’ consistency.
Loss of concrete surface section can be visibly evident with the aggregates protruding out of the surface. Depths of degradation occurring at up to 25mm per annum are commonplace with host concrete structures being destroyed in very short periods of time.