ICPI 25th Anniversary Commemorative Publication ICPI 25th Anniv Commemorative Album 0219 web - Page 5

A concrete paver street in Delft, The Netherlands, undergoing reconstruction in the 1980s. Workforce development during Dutch street reconstruction. guidelines on manufacturing and use of interlocking concrete pavement in road construction. The German Institute of Standards issued its first concrete paver standard in 1964 as DIN 18501. Today, the market for pavers and slabs is about one square meter (10.7 sf ) per capita, or about 80 million m 2 (861 million sf ). This paving tradition emerged from about 80% of the country being below sea level. Land reclaimed from the sea is laced with ditches to remove excess ground water. Initially windmills and now electric pumps deliver this water to ditches that eventually drain to dikes at the North Sea. In 1951, concrete pavers emerged in The Netherlands from a shortage of clay paving bricks. Most of the manufactured clay units were directed to replacing damaged or destroyed buildings from World War II. The shortage briefly paused the one thousand-year tradition of using units made with river clay for urban streets, and more recently, with vitrified clay units. Dewatering the soil causes settlement. While rates vary, it can be as much as 4 to 6 inches (100 to 150 mm) over five to ten years. Dutch buildings don’t settle much because they rest on pilings for foundations. However, settled pavements must be raised regularly. Stone and clay paving units enabled periodic removal, raising the road base, and then reinstating the same paving units. 1973–1974 1975 1977 Late 1970s 1980 1982 Durastone & KNR Concrete start paver production near Toronto U.S. paver manufacturing starts, Canadian manufacturing grows; Uni- Group formed Durastone & KNR purchased by North American Stone Company; renamed Unilock Interlocking Paver Manufacturing Association forms for industry promotion Willy Schultz’s Paver Systems purchased by Germany’s Schmitt Beton C936 U.S. concrete paver standard issued by ASTM I C P I C O M M E M O R AT I V E P U B L I C AT I O N • 3