Acid-free paper durable acid-free paper. Archival paper is meant to be used for publications of high legal, historical, or significant value. In the USA, such paper must also be approved in accordance with the ANSI standards. The international standard for "permanent" paper is ISO 9706 and for "archival" paper, the standard is ISO 11108. Often, cotton rag paper is used for archival purposes, as it is not made from wood-based pulp. Thus, "archival paper" is sometimes broken down into two categories: Acid-free paper Acid-free paper is paper that if infused in water yields a neutral or basic pH (7 or slightly greater).
Alkali–silica reaction ASR in the presence of siliceous aggregates and water is to maintain the concentration of soluble alkali (NaOH and KOH) at the lowest possible level in concrete, so that the catalysis mechanism becomes negligible. The alkali-silica reaction mechanism catalysed by a soluble strong base as NaOH or KOH in the presence of Ca(OH) (alkalinity buffer present in the solid phase) can be compared with the carbonation process of soda lime. The silicic acid (HSiO or SiO) is simply replaced in the reaction by the carbonic acid (HCO or CO). In the presence of water or simply ambient moisture, the strong