在线英语听力室_免费在线英语听力学习网站

New Concrete Recipes Could Cut Cracks 能够对抗公路裂化的新型混凝土配方

There's a stretch of highway in Pennsylvania, along U.S. 422. "And like every probably 20 feet you see a big pothole¹ or cracking at the joint². Like everywhere. It was so bad." Yaghoob Farnam is a construction materials engineer at Drexel University in Philly. And this road is pretty much his worst nightmare. "Yeah and just imagine I was driving like 60 miles per hour, I could see, I could feel it, I was driving, I was so mad, like, 'what is going on with this?'"

宾夕法尼亚州有一段美国422号高速公路的延伸路段。“几乎每隔20英尺，你就会在接合处看到一个大凹坑或者裂化。它们好像无处不在。而这真是糟透了。”雅各布·法南姆是费城德雷塞尔大学的一名建筑材料工程师。这条路对他来说简直是最可怕的噩梦。“想象一下，我以时速60英里的速度在这条路上行驶，我能看到、感觉到这些凹坑，而我正在开车，而且感到非常生气，恨不得冲它吼‘这条路到底是怎么回事?’”

The culprit, he says, may be calcium³ chloride road salt, used to de-ice highways in the winter. Because calcium chloride reacts with a compound in concrete called calcium hydroxide to form something called calcium oxychloride. "It's a huge molecule⁴ that causes a lot of pressure inside concrete. And starts degradation⁵ of concrete."

法南姆说，罪魁祸首可能是用以冬季公路除冰的氯化钙路盐。由于氯化钙会与复合混凝土中一种叫做氢氧化钙的物质发生反应，从而形成一种叫做氯氧化钙的物质。“这是一种会给混凝土造成很大压力的巨大分子，并且会使混凝土开始降解。”

The solution? Novel blends of concrete that use cheap leftover⁶ materials from the coal and steel industries: fly ash, silica fume⁷ and slag⁸. In his latest work, Farnam and his team created plugs of these experimental concretes, and submerged them in salty solutions—along with plugs of conventional concrete. Then they eavesdropped⁹ on any cracking with high-sensitivity acoustic¹⁰ sensors¹¹. And they tracked heat flow through the material, to monitor chemical reactions.

解决方案？——使用来自煤炭和钢铁工业中廉价的剩余材料——粉煤灰、硅粉和矿渣的新型混凝土混合物。在其最新研究中，法南姆和他的团队发明了这些实验混凝土堵头，并将其与传统混凝土堵头一起浸入含盐的溶液中。然后，他们通过高灵敏度的声传感器对裂化声进行窃听，并通过这些材料进行热流量跟踪，以监测化学反应。

The results: concrete slugs made with ingredients like fly ash and slag held up remarkably¹² well after more than a month. Whereas normal concrete was cracked to pieces in just a week. Their recipes are in the journal Cement and Concrete Composites.

结果显示:用粉煤灰和矿渣等原料制成的混凝土块，一个多月后质地仍保持得很好，而普通混凝土仅在一周内就裂成了碎片。他们的制作配方发表在《水泥和混凝土复合材料》杂志上。

Farnam says some states have actually started using this sort of concrete—because it's already known to make the material more durable¹³ against other factors, like corrosion¹⁴ of internal steel reinforcement. As for those cracks on U.S. 422, and elsewhere? Farnam has another project in the works—to apply a bacterial¹⁵ slurry, which forms limestone¹⁶ when it interacts with salt, plugging up the gaps. But he says that work is still a ways…down the road.

法南姆表示，其实一些州已经开始使用这种混凝土了，因为相对其他因素——例如钢筋内部腐蚀，它能使材料更耐用的特性已被人们熟知。至于美国422号公路和其他公路上的裂痕？法南姆正在进行另一个项目——即填涂能与盐相互作用形成石灰石的细菌泥浆，从而封堵开裂处。不过他表示，该项目仍然……还在进行中。