Eastern Thought Permeates
The China Construction Units Association (CCUA) hosted the 10th International Conference on Concrete Block Paving (ICCBP) in Shanghai, People’s Republic of China, November 24-26, 2012.
Home to about 22 million inhabitants, the conference setting of Shanghai represents China’s door to the west, a place where ideas meet and become industries.
The triennial conference consisted of 163 delegates: 44 from foreign countries and the rest from China, mostly paver manufacturers and suppliers. Twenty-five papers were presented, and several more were provided during the conference proceedings.
Conference papers focused on sustainable aspects of segmental concrete pavements, including permeable interlocking concrete pavement, and the use of recycled materials in concrete paving units. Among the recycled materials examined were foundry sand, flyash, and waste from building demolition. A discussion about how to reduce worker fatigue and accidents on construction sites expanded the meaning of sustainable construction.
Permeable pavement for heavy load applications received a boost from the full-scale load testing and design guidelines published by the UK industry association, Interpave. Design methods were examined using a perforated asphalt layer under the bedding layer, as well as cement-stabilized aggregates not unlike pervious concrete. North American design guidelines and best practices for permeable pavement construction and maintenance were also presented.
New products presented included new paver shapes from Spain and China. Two papers from Japan examined the reuse of pavers after earthquakes and the recent tsunami, something other paving materials don’t offer. Pictures of the striking damage and fast repair provided an impressive lesson in pavement resilience for any region subject to earthquakes or tsunamis.
A significant discovery of the conference was that 2.6 billion sf (260 million m2) of concrete pavers were sold in 2011 and that about 2.4 billion sf (240 million m2) are expected in 2012, due to a slight downturn in the Chinese economy. (A slight downturn means a national economy growing at 7 percent annually instead of 9 percent.) These production figures equate to about 2 sf (0.2 m2) per capita. While municipal governments embrace segmental paving for sidewalks and plazas, their use appears restricted from roads. This raises the question of what might be required from transportation authorities to accept interlocking concrete pavements for roads.
Supply Chain Optimization
The conference included a technical tour of a paver plant about 75 miles (120 km) from Shanghai, equipped with Japanese automated manufacturing equipment similar to that in North America.
The plant had the benefit of being located next to a river so that aggregates and cement could be delivered economically, and likewise, the pavers could then be easily loaded back onto the barges.
Pavers, slabs, permeable and pervious (no fines) pavers were the norm for this manufacturer.
China exploring additional uses
In China, interlocking concrete pavements are used mostly for pedestrian sites. One paper explored using interlocking concrete pavements for the shoulder lane of highways as a means to expand the industry.
The Chinese have significant experience with supplying pavers to Hong Kong International Airport (about 5 million sf or 500,000 m2) in commercial heavy aircraft parking, as well as many hec-tares in container handling areas in the ports of Hong Kong and Yantian. The paver supplier told the stories behind these projects and why concrete pavers were the preferred choice, i.e., cost and performance.
Permeable interlocking concrete pavements are now seeing expanded use under rubber-tracked military vehicles in the U.S., thereby demonstrating their ability to remain stable under significant lateral loads.