On Issue of Permissible Content of Ammonium Ions in Chemical Additives for Concrete

Nitrogen-containing compounds that enter concrete together with raw materials, in particular chemical modifiers of mixture and concrete, as well those present Portland cement, are capable forming ammonia a result decomposition. The processes formation emission cause both deterioration the atmosphere residential premises reason for decrease strength operational safety indicators reinforced structures. These circumstances necessitate research development methods determining safe amount ammoniumcontaining additives concrete. Most often, nitrogen-containing contain plasticizing additives, antifreeze complex setting hardening accelerators. According to Amendment No 2 STB (Standards Republic Belarus) 1112–98 “Additives Concrete. General Requirements”, content ammonium ions should not exceed 100 mg/kg (except antifreeze). At same time, some including plasticizers, which have been successfully used more than one year without identified problems emission, do fit into established norm. To determine maximum permissible concentration (MPC) salts it is necessary know dependence from on various factors, particular, mass surface area emitted, structures, temperature, humidity air exchange rate room. lesser extent, will be affected by characteristics reaction conditions hydrolysis paper provides formulas calculating introduction ammonium-containing additives. It shown that, spite оf above-standard C-3, LST UP-4, cases does (MPC). volume determined only but also large extent structural technological scheme building parameters loading With known MPC room, given room formula allows you calculate additive mixture, exceeding ensure compliance premises.