WEBVTT - Why Does Ancient Roman Concrete Outlast Our Own? 0:00:01.920 --> 0:00:07.000 Welcome to brain Stuff production of iHeartRadio. Hey brain Stuff, 0:00:07.080 --> 0:00:11.360 Lauren Vogel bomb here. Why are millennia old ancient Roman 0:00:11.440 --> 0:00:15.680 piers still standing strong is veritable concrete islands, while modern 0:00:15.800 --> 0:00:19.240 concrete structures built only decades ago crumble from an onslaught 0:00:19.320 --> 0:00:22.840 of wind and waves. The answer lies in until now 0:00:22.920 --> 0:00:27.400 undocumented Roman recipe. Researchers at the University of Utah have 0:00:27.440 --> 0:00:30.640 discovered that a seawater filters through piers and breakwaters made 0:00:30.640 --> 0:00:34.720 of age old Roman concrete, the structures actually become increasingly 0:00:34.800 --> 0:00:38.479 stronger because of the growth of interlocking minerals, including some 0:00:38.600 --> 0:00:41.960 minerals that are rare or expensive to cultivate in lab settings. 0:00:42.680 --> 0:00:46.080 The study, published in the journal American Mineralogist, found that 0:00:46.200 --> 0:00:49.960 as seawater percolates through the concrete in the piers and breakwaters, 0:00:50.320 --> 0:00:52.920 it dissolves parts of the volcanic ash that was used 0:00:52.960 --> 0:00:57.160 in construction. This allows new minerals like aluminum, tobomerite, and 0:00:57.280 --> 0:01:01.520 philip site to form from the leached fluid. It's These minerals, 0:01:01.560 --> 0:01:04.640 similar in shape to the crystals and volcanic rocks, then 0:01:04.760 --> 0:01:08.880 form interlocking plates in gaps within the ancient concrete, making 0:01:08.920 --> 0:01:12.800 the concrete stronger over time. This is pretty much the 0:01:12.800 --> 0:01:15.680 opposite of what happens to modern concrete structures, which are 0:01:15.680 --> 0:01:18.760 worn down by the elements and become increasingly cracked and 0:01:18.800 --> 0:01:22.440 brittle as pores and gaps are compromised by infiltrating sea water. 0:01:23.640 --> 0:01:27.040 So why aren't we using Roman style concrete? For one, 0:01:27.480 --> 0:01:30.120 we don't know the recipe. We may think we're at 0:01:30.160 --> 0:01:32.640 the height of human knowledge, and certainly the Internet gives 0:01:32.640 --> 0:01:35.120 everyone who has access a leg up, but the ancients 0:01:35.160 --> 0:01:37.880 had techniques and technologies that have been lost to time. 0:01:38.880 --> 0:01:42.040 Although University of Utah geologist and lead study author Marie 0:01:42.120 --> 0:01:45.720 Jackson has poured through ancient Roman texts, she hasn't yet 0:01:45.720 --> 0:01:48.960 discovered a precise method for mixing the marine mortar, but 0:01:49.200 --> 0:01:52.360 she's working with geological engineers to recreate the right mix. 0:01:53.280 --> 0:01:57.000 There's also a load bearing issue. Ancient is the key 0:01:57.040 --> 0:02:00.160 word in these Roman structures, which took a long long 0:02:00.200 --> 0:02:03.920 time to develop their strength from seawater. Young cement built 0:02:03.960 --> 0:02:07.640 using a Roman recipe probably wouldn't have the compressive strength 0:02:07.680 --> 0:02:11.840 to handle modern use, at least not initially, but that 0:02:11.880 --> 0:02:15.400 doesn't mean concocting a concrete mix using Roman engineering savvy 0:02:15.440 --> 0:02:18.840 wouldn't be useful. The concrete could potentially be used to 0:02:18.919 --> 0:02:22.880 replace other corrodable building materials like steel and modern concrete 0:02:23.080 --> 0:02:26.799 in newly constructed tidal lagoons, for instance, and other see 0:02:26.919 --> 0:02:30.400 or see adjacent structures. Maybe in the future we can 0:02:30.400 --> 0:02:38.320 put this ancient knowledge to use. Today's episode was written 0:02:38.320 --> 0:02:40.920 by Laurie L. Dove and produced by Tyler Clang. Brain 0:02:40.919 --> 0:02:43.400 Stuff is production of iHeart Radio's How Stuff Works. For 0:02:43.480 --> 0:02:45.440 more in this and lots of other load bearing topics, 0:02:45.520 --> 0:02:48.080 visit our home planet, how stuff Works dot com, and 0:02:48.200 --> 0:02:50.400 for more podcasts from our heart Radio, visit the iHeart 0:02:50.480 --> 0:02:52.880 Radio app, Apple Podcasts, or wherever you listen to your 0:02:52.880 --> 0:02:53.560 favorite shows.