Cement manufacture and alkali levels

Cement is produced in New Zealand in modest-sized plants which currently produce up to a million tonnes per year. Since 1945, when records of alkali analyses first became available, much of the cement produced or imported contained less than 0.7% alkalis1. The exceptions are one of the original works, which until 1968 often produced cement with alkalis in excess of 1.0% (see Figure 9.2), and two smaller, now defunct, works which operated for about a decade. The high-alkali cements produced by these two small plants were not used in any large-scale construction or public works. Until the recent installation of a suspension preheater-type kiln system, one of the larger works consistently produced cement with an average of 0.3% alkalis. Thus low-alkali cements have always been readily available in New Zealand, and since 1968 all cement produced has contained less than 0.6% alkalis. This ready availability of low-alkali cement has been an important factor in limiting AAR in New Zealand.

Updated: 20 сентября, 2015 — 1:05 пп