OF ALL the plastic produced since the 1950s, less than 10% has been recycled. The vast majority ends up being dumped, most of it in landfill. Some is left to litter the natural environment, where it can get into rivers and wash out into the sea. The plastic-waste problem will worsen before it gets better: some 380m tonnes of the stuff are likely to be made this year. That is more than three times as much as the 120m tonnes of bitumen produced annually, most of which goes into building the world’s roads.
上世纪50年代以来，塑料制品有回收利用只有不到10%。绝大多数最终都是丢弃掉，而其中大部分扔进了垃圾填埋场。有些丢弃在自然环境中，冲到河里，流入大海。废塑料问题在得到好转前还会继续恶化：今年可能会产生3.8亿吨废塑料，每年1.2亿吨沥青产量的三倍多——大部分沥青用于世界各地的公路修建。
There is a connection. Just as plastic is derived from petrochemicals, bitumen is produced as a by-product of refining oil. Both are polymers, which consist of long strands of molecules bound together firmly. It is this characteristic that makes plastic strong and contributes to its great longevity. Such features are also useful for road builders, who use hot bitumen to bind together aggregates made from broken rocks and stones, into what is commonly known as asphalt. All of which has got some people thinking: why not swap one polymer with another?
这之中是有关联性的。就像塑料是从石化产品中提取的一样，沥青也是炼制油的副产品。两者都是聚合物，由紧密结合在一起的长链分子组成。正是这种特性使塑料坚固耐用，对道路建造者也很有用，将热沥青与碎石和碎石制成的碎石粘合在一起，形成俗称的沥青。这都让人想到一个问题：为什么不把一种聚合物替换成另一种呢?
Recycled plastic is already used to make some products, such as guttering and sewage pipes. Now attention is turning to roads. On September 11th in Zwolle, a town in the Netherlands, a 30-metre bicycle track made from 70% recycled plastic and the rest from polypropylene was opened. It will be used to test a product called PlasticRoad, which is being developed by two Dutch firms—KWS, a road builder, and Wavin, a firm that makes plastic piping—in partnership with Total, a French oil-and-gas firm.
回收的塑料现在可用来制造一些产品，如排水沟和污水管。现在的注意力转向道路。9月11日，在荷兰的Zwolle镇新开了一条30米长的自行车道，由70%的回收塑料以及其他聚丙烯材料制成。这条路是用来测试荷兰公司KWS和Wavin开发的一种名为“橡皮泥路”的产品。KWS是一家道路施工公司，Wavin是一家与法国油气公司道达尔合作生产塑料管道的公司。
PlasticRoad is prefabricated in a factory as modular sections. The sections are then transported to the site and laid end to end on a suitable foundation, such as sand. Because these sections are hollow, internal channels can be incorporated into them for drainage, along with conduits for services such as gas and electricity. For the Zwolle project, sections that were 2.4 metres long and 3 metres wide were used. These were fitted with sensors to measure things such as temperature, flexing and the flow of water through the drainage channels. A second pilot cycleway is being built in the nearby town of Giethoorn.
“塑料路面”是作为模件，在工厂里先预制，然后运送到工地，并在合适的地基(如沙子)上首尾连接。由于这些模件是中空的，内部的管道可以和管道一起用于排水，比如天然气和电力。Zwolle项目用长2.4X3米规格。这些装置装有传感器，用来测量诸如温度、弯曲度和排水管道的水流。另一个试点自行车道正在邻近的吉欧恩镇修建。
Smart roads, too
智能公路同样如此
If all goes well, the inventors hope to develop the idea and make the sections entirely from recycled plastic. Paths, car parks and railway platforms could follow. Eventually, sections for use as actual roads are planned. These could contain sensors for traffic monitoring. In time, the circuits in the plastic roads might extend to assisting autonomous vehicles and recharging electric cars wirelessly.
如果一切顺利，塑料道路的发明者们希望改进这一设法，完全用回收塑料制作模件。在道路、停车场和铁路站台也能用上。最终，在城市规划里将模件用于实际道路。这些可能包含用于交通监测的传感器。随着时间的推移，塑料路面上的电路可能会延伸到协助自动驾驶汽车并为电动汽车无线充电。
Prefabricated plastic roads should last two-to-three times longer than conventional roads and cost less, the companies claim, mainly because construction times would be reduced by almost two-thirds. Anti-slip surfaces could be incorporated, too, including crushed stones which are traditionally used to dress road surfaces. The sections, when replaced, can also be recycled. But engineers will be watching to see how the track stands up to wear and tear and if the hollow structure causes resonance, which would make such a road unduly noisy.
这两家荷兰公司表示，预制塑料路面的使用寿命应该是传统道路的两到三倍，而且成本更低，主要原因是施工时间将减少近三分之二。防滑表面也可以合并，包括传统上用于修饰路面的碎石。更换后的部分也可以回收利用。不过，工程人员会观察这条轨道如何承受磨损，以及这条空心结构是否会引起共振，从而使这条道路噪音过大。
An alternative method of using recycled plastic is to mix the material into hot bitumen when making asphalt. A road is about to be built this way on the campus of the University of California, San Diego, to test a number of specialist roadmaking plastics developed by MacRebur, a British firm. Each mix is produced from plastic that is not easily or cheaply recycled and so typically ends up in landfill, says Toby McCartney, who founded the firm in 2015 with a group of colleagues.
使用再生塑料的另一种方法是在制作沥青时将材料混合成热沥青。加州大学圣地亚哥分校即将以这种方式修建一条道路，测试由英国公司MacRebur开发的专业道路塑料。与同事在2015年创立MacRebur的托比•麦卡特尼(Toby McCartney)表示，每一种混合物都是用塑料制成的，这种塑料回收麻烦，成本也不低，因此通常会被扔进垃圾堆。
MacRebur cleans and sorts the plastic and then grinds the waste into flakes or pellets. The plan is for this part of the process to be carried out in the localities where roads are being laid or repaired, so that local waste is used to produce local roads. Each mix can contain 20 or so different polymers for specific surfaces. One mix, for instance, might be suitable for a bus lane that carries heavy loads. Another would provide some flexibility in an area of turning traffic, such as a roundabout, where lateral forces from vehicles’ wheels can stretch the surface causing it to tear. Extremes of heat and cold can also be adjusted for. And because the addition of plastic helps to seal up small holes, which allow water to get below the surface of a road and cause it to break up, the modified asphalt can help to prevent potholes.
MacRebur清洁和分类塑料，然后研磨成薄片或小球。该计划是在正在铺设或修理道路的地方进行这一进程的一部分，以便用当地的废物来生产当地的道路。每一种混合物可以包含20种左右不同的聚合物用于特定的表面。例如，一种混合物可能适用于载重量较重的公共汽车车道。另一种方法是在转向交通的区域提供一定的灵活性，比如环形交叉路口，车辆车轮的侧向力会拉伸路面，导致路面撕裂。可以针对极端的热和冷条件进行调节。另外，由于塑料的加入有助于封住小洞，这些小洞会让水渗到路面下面，导致路面破裂，因此，改性沥青有助于防止路面出现坑坑洼洼。
The company’s plastic mixes have already been used in roads, car parks and airport runways in various parts of the world. One of the oldest projects is a stretch of road in Cumbria, in north-west Britain, which is extensively used by heavy lorries. This used to need resurfacing every six months or so, but with the addition of plastic it is still going strong after two years, says Mr McCartney. When resurfacing is needed, the material can be recycled again.
MacRebur的塑料混合物已用于世界各地的道路、停车场和机场跑道。最早的一个项目是英国西北部坎布里亚郡的一段公路，是重型卡车繁忙行驶路段。麦卡特尼称，过去公路需要每六个月左右换一次路面，但加入了塑料后，道路在两年后仍然很好用。当需要进行表面处理时，材料可以再次回收。
Cleaning and sorting plastic made out of multiple polymers can be relatively expensive, especially if it is used to make low-value products such as packaging. But using such plastic as a replacement for bitumen is cost-effective, claims Mr McCartney. As an example, he says that a tonne of bitumen might cost around £400 ($521) in Britain. A recycled-plastic additive for a standard road works out at £300-£350 a tonne. The additive would replace a proportion of the bitumen, so there are savings to be made. At present 5-10% of the bitumen is replaced by the additives, but this could be increased to 25%.
用多种聚合物制成的塑料进行清洗和分拣可能会相对昂贵，特别是如果用它来制造包装等低价值产品的情况五。不过,麦卡特尼称，用这种塑料代替沥青是划算的。他举例称,在英国，一吨沥青的成本可能会约£400($ 521)。再生塑料添加剂标准的道路施工£300 -£350 /吨。这种添加剂可以代替一部分沥青，因此可以节省成本。目前，5% -10%的沥青被添加剂取代，但这可以增加到25%。
Mr McCartney decided to develop specialist recycled-plastic additives after watching a practice sometimes employed in India to repair potholes. Plastic waste collected by pickers is piled into the hole and then set alight with diesel to form a molten mass. It is crude and polluting, but it provides a fix of sorts. A number of roads in India are also made by mixing chopped-up plastic into bitumen.
麦卡特尼在发现印度的一种修补坑洞的方法后，决定开发专门的回收塑料添加剂。由采集者收集的塑料垃圾被堆放到洞中，然后用柴油点燃，形成熔融物质。这种物质是粗糙的，会产生污染，不过却实现了某种分类。印度的许多道路是用将塑料弄碎，混进沥青里来铺设。
Australia is another country that is starting to recycle plastic into roads. Earlier this year a 300-metre stretch was completed in Rayfield Avenue, Craigieburn, a suburb of Melbourne, using a substance called Plastiphalt. This consisted of recycled material from more than 200,000 plastic bags and packaging, 63,000 crushed glass bottles and toner from 4,500 printer cartridges. All this was blended into 50 tonnes of reclaimed asphalt to create a total of 250 tonnes of road-building material. The road will be monitored to see how it performs.
另一个开始在道路上回收塑料的国家是澳大利亚。今年早些时候，墨尔本郊区克雷吉伯恩的瑞菲尔德大道(Rayfield Avenue)使用一种名为塑化玻璃(Plastiphalt)的物质，完成了长达300米的施工。原料包括从20多万个塑料袋和包装中回收的材料，从4500个打印机墨盒中回收63000个碎玻璃瓶和墨粉。这些材料混合成50吨再生沥青，构成总共250吨的道路建筑材料。这条路将在监测之下，了解使用状况。
Stuart Billing of Downer, a firm involved in constructing the road, said that the cost of using the recycled materials was comparable with building a road in the usual way. But the road is expected to last a lot longer and prove better at coping with heavy traffic.
参与修建这条道路的Downer公司的Stuart Billing称，使用回收材料的成本与用通常的方式修建一条道路差不多。但这条路预计会持续更长的时间，并能更好地应对拥挤的交通。
Officials in Craigieburn reckon that the amount of rubbish used to construct the road, all of which was diverted from landfill, is equivalent to what Rayfield Avenue’s residents would have put into their recycling bins over the past ten years. One of the biggest complaints to local councils is about the state of the roads, especially potholes. Households in Australia and elsewhere might well do more sorting and recycling of plastic if they knew it could result in a smoother drive.
克雷吉伯恩镇的官员估计，用于修建这条道路的垃圾数量(所有垃圾都是从垃圾填埋场转移过来的)相当于过去10年里雷菲尔德大道上居民将垃圾放入回收箱的数量。向地方议会最多的一个抱怨就是道路状况问题，尤其是坑坑洼洼。如果澳大利亚以及其他国家的家庭知道塑料可以带来更顺畅的驾驶体验，他们可能会对塑料进行更多的分类和回收。
编译：何坤
编辑：翻吧君
来源：经济学人（2018.09.13）
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