Emission characteristic of ammonia in cement mortars using different sand from area of production

This paper discusses the influence of organic matter contained in aggregate on the emission characteristic of ammonia (NH₃) from cement mortar. NH₃ can be released to indoor-outdoor environment through diffusion in mortar (or concrete) and have resulted in the increasing air pollution, and especially well known as a harmful gas for the human body. The concentration of NH₃ released from cement concrete was then compared to the contents of organic matter contained in the aggregate. The result indicates that the contents of organic matter in the aggregate significantly differ with types of aggregate from different areas of production. The organic matter becomes organic nitrogen through the process of microbial breakdown for a certain period and pure ammonium ion (NH₄⁺) is produced from the organic nitrogen. The NH₄⁺ was reacted with alkaline elements in the cement and released as NH₃ from cement concrete through a volatile process. The released NH₃ was proportional to the contents of NH₄⁺ adsorbed in the aggregate from different areas of production and the concentrations of NH₃ emission from cement mortar according to the aggregate differ by more than 4 times.