For decades, cement has been the preferred building material in North Korea. Limestone, a key ingredient in making cement, is in great abundance, as is high-quality river sand, an aggregate for making concrete. Assessing the cement industry through satellite imagery, however, is a difficult task.
Cement factories are typically located near the limestone mines they are dependent upon for source minerals and near railroads or major highways to facilitate transport to concrete plants located near the towns or major projects they serve. The larger factories also tend to be located near large metropolitan areas where the need for cement is greatest, but the limestone quarries also dictate their locations. Smaller cement factories tend to be located in more remote regions, servicing smaller projects and less accessible towns where transportation infrastructure is not as robust.
While cement factories tend to have some unique signatures that can be observed on imagery, infrequent collection of many of these factories hinders the ability to closely and credibly monitor traffic and activity levels. Moreover, interior changes to factory buildings, where production processes may be modernized, are hidden from view. Despite these constraints, establishing some baselines about the status of the industry is still possible.
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