The logic was ruthless and clear. Katanga's ore had to be refined near the mines before transport - carrying raw ore to Europe for processing would have been uneconomic, so the refining happened on site. That meant smelters, which meant furnaces, which meant refractory buildings. The workforce numbered in the tens of thousands and had to be housed, which meant worker compounds and barracks. The railway lines that would carry the refined copper north to Lobito in Angola or south to Beira in Mozambique required bridges, culverts, embankments. Every one of those things needed cement, and cement is a commodity whose price doubles for every hundred miles of bad road. Importing it from Europe was insane. Making it locally from the limestone deposits of the Katanga plateau - that was merely difficult, and difficulty was something the Union Miniere specialized in.

Ciments du Katanga was capitalized by a who's who of Belgian colonial industry. The Societe Belge et Miniere du Katanga provided mining expertise. The Compagnie du Congo pour le Commerce et l'Industrie - the oldest of the great Congo trading houses - brought logistics. The Banque de Paris et des Pays-Bas supplied the finance. The Belgo-Katanga consortium knit the local interests together. Early directors included Alphonse van Gele, a colonial administrator who had explored the Ubangi River in the 1880s, and Louis Valcke, another veteran of the early Congo Free State years. These were not businessmen stepping fresh into Africa. They were the second generation of the Belgian colonial enterprise - men whose predecessors had helped run King Leopold's personal colony before the Belgian state took it over in 1908 - applying the methods of scale they had learned in that earlier, bloodier phase to the industrial exploitation of copper.

The first cement factory opened at Lubudi in Katanga at the start of 1924 - just two years after the company's founding, remarkable speed for a plant in the African interior. A fibrocement factory followed in 1929, producing artificial stones, roofing tiles, pipes, and corrugated sheets. A second cement plant was founded at Likasi in 1953, making a cement that was particularly resistant to groundwater sulphates - valuable for foundation work in the mineral-rich and acidic soils of the Copperbelt. By 1958 total production capacity had reached 200,000 tonnes annually: 180,000 tonnes of cement plus 20,000 tonnes of clinker sold on to the cement works at Jadotville (modern Likasi). The plants supplied the Union Miniere first, then other Katangan industrial companies, and eventually the two Kasai provinces to the north.

The Congo's independence in 1960 set in motion a slow series of reorganizations. Under the Belgian transitional law of 17 June 1960 the company formally came under Belgian rather than Congolese jurisdiction. Two years later, on 13 February 1962, Ciments du Katanga transferred its Lubudi facilities and its industrial activities to a new Congolese-incorporated entity: Ciments et Materiaux de Construction du Katanga, abbreviated CIMENKAT. Then came the political whiplash. On 31 December 1974, as part of Mobutu's wave of Zairianization, CIMENKAT was nationalized and became entirely state-owned. Less than two years later, on 17 September 1976, it was handed back to its former shareholders. By 1995 those shareholders were Gecamines, the state mining giant, with 49.8 percent; EGINTER with 47.4 percent; and two smaller Belgian stakes from CBR and Eteroutremer. The arc from 1922 royal decree to 1970s nationalization to 1990s mixed ownership traces the whole complicated history of Congolese industry in miniature.

Both factories still operate, though their fortunes have tracked the broader volatility of Congolese industry. Lubudi and Likasi remain important cement producers for the Copperbelt mining sector, and the cement they make still goes into the foundations of mines, smelter buildings, and worker housing - much as it did a century ago. From the air, the Likasi plant shows as a cluster of kilns and silos on the flat Katangan plateau, with rail sidings running off toward the mining towns. The landscape around it is miombo woodland scarred by mining and by the smelter plumes that still mark the sky on production days. The cement plants are older than the Democratic Republic of the Congo itself. They were older than Zaire before that. They have outlived three political systems and will probably outlive whatever comes next.