Cement production contributes an estimated 6% of global greenhouse-gas emissions, say scientists who are trying to chip away at the pollution problem. Two start-ups, one in Canada and another in Arizona, are among the newer entries in the effort to produce cleaner cement and concrete.
 |
| WAGNER |
类似于当今化学混合物的管道方式，将设备改装到混凝土搅拌机上2进入混凝土。“当2在混合过程中添加到混凝土中2该公司的网站说：“与水反应形成碳酸盐离子。然后，碳酸盐迅速与从水泥释放到迅速形成石灰石状材料的钙离子反应。该矿物是以分散在混凝土混合物中的纳米材料形式产生的。”
CO的转换2气体到固体碳酸盐永久隔离混凝土中的气体。该公司在砖石领域工作了几年，但刚刚开始使用该技术进行现成混合。瓦格纳说：“我们预计到今年年底将有几个完全运行的现成混凝土装置。”
碳菌隔离不同的CO2, depending on the individual producer's mix design, Wagner adds. "Typically, the amount of CO2that is sequestered is around 1% of the weight of cement," she explains. "In ready-mix-concrete applications, the addition of CO2还可以解锁材料性能增强功能，这可能导致混合设计优化，并进一步加以实现。2减少。”
 |
| 结石 |
Stone stumbled on this discovery in 2002, while pursuing a doctorate at the University of Arizona. "It has taken years to get just a basic understanding of the chemistry involved," he says. Waste steel dust makes up 60% of the material's dry ingredients; fly ash is 20%, and ground limestone is another 10% of the mix. Exposing the dry ingredients to water and CO2在环境温度”驱动氧化反应ion that forms the cementing iron-carbonate mineral matrix," Stone says, adding that hydrogen gas "is a by-product that might be harvested at large-scale operations."
由此产生的糊状物具有令人印象深刻的品质，达到5,500至6,500 psi，“尽管我们已经达到了10,000，”斯通说。经过四天的水和CO固化2暴露于28天的湿润疗法后，船舶可以达到与波特兰水泥相当的强度。在10天内实现了全部强度。弯曲强度测试表明，当两个测试样品均具有1％的玻璃纤维时，Ferrock的强度是波特兰的七倍。凭借这些品质作为潜在奖项，亚利桑那州立大学副教授兼土木工程师的Stone和Narayanan Neithalath正在进行研究以改善产品。
费罗克的主要弱点是“由于CO的扩散，反应的缓慢2进入浓稠糊状物中的间质水，并随后形成碳酸铁，“石材屈服。使用在碳化板，墙壁和其他厚实结构中有效的方法，将气体通过嵌入式薄壁墙注入新鲜的糊状物中钢导管每四英寸用¼英寸的孔孔穿孔一次。需要碎石骨料来使倒入材料多孔并允许CO2斯通说，渗透到它，但“这种方法牺牲了一些力量”。“我们正在研究介绍所有公司的方法2最初，与水一起使随后的瓦斯不必要。”
Storage, preparation, delivery and placement of Ferrock are conventional but with different materials. In the dry state, Ferrock is just like portland cement, Stone says, noting, "After mixing with water, it will not harden until exposed to CO2或者允许干燥，这可以在空气中进行氧化。需要孔隙率，可以将玻璃粉碎成各种尺寸的聚集体并代替混合物中的沙子和砾石。不需要倒塌测试。，“ Neithalath不是反应中的试剂。您需要水均匀地分散颗粒，并将二氧化碳携带在材料中以形成这些结合剂。”
Despite its promise, Ferrock faces a major hurdle in gaining industry acceptance. To overcome market inertia, the challenge of meeting engineering properties and the resistance of standard-setting organizations and users reluctant to bet their million-dollar project on an unproven material, "it takes a long time for the industry to accept change," says Steve Kosmatka, vice president of research and technical services for the Portland Cement Association. Portland cement was invented in England in 1824 but was not widely used in the U.S. until the 1860s, he notes. Its advantages over natural cement were so great that it became the standard, but it still took decades. Supply of key materials is a further challenge, Kosmatka and Stone concur. Waste steel dust from large steel shot blasting has met the needs for research, but, "on a large scale, we might tap the direct reduced iron supply, which is huge, but it's a feedstock for steel production and not a waste, so it's much more expensive," Stone says.
可持续发展副总裁詹妮弗·瓦格纳（Jennifer Wagner）表示，加拿大公司碳壳技术公司，新斯科舍省达特茅斯（Nova Scotia）为砖石和现成混凝土生产商提供了一项技术，可将废物二氧化碳（CO）隔离为混凝土。她说：“该过程与任何类型的常规水泥一起工作。”与碳菌一样，大多数“绿色”混凝土从常规的波特兰水泥开始。使用钢灰尘作为基本组件的Ferrock采用了不同的方法。尽管波特兰水泥的生产需要大量的能量（从化石燃料发出的co中）不需要能量输入。Iron Shell LLC的发明家兼创始人戴维·斯通（David Stone）说：“减少铁中的体现能量驱动了氧化反应。”
