As previously described in the two sections dealing respectively with ASR catalysis by alkali hydroxides and soda lime carbonation, soluble NaOH and KOH are continuously regenerated and released into solution when the soluble alkali silicate reacts with to precipitate insoluble calcium silicate. As suggested by Davies and Oberholster (1988), the alkali-silica reaction is self-perpetuating as the alkali hydroxides are continuously regenerated in the system. Therefore, portlandite is the main buffer of in the solid phase. As long as the stock of hydroxides in the solid phase is not exhausted, the alkali-silica reaction can continue to proceed until complete disparition of one of the reagents ( or ) involved in the pozzolanic reaction.