1 00:00:00,000 --> 00:00:03,490 [ MUSIC ] 2 00:00:03,510 --> 00:00:14,440 Cementing Our Place in Space -- presented by Science@NASA 3 00:00:14,460 --> 00:00:17,580 As your dog drags you around the block for his morning walk, 4 00:00:17,600 --> 00:00:21,390 you’re probably not thinking about the wonders of the neighborhood sidewalk. 5 00:00:21,410 --> 00:00:28,490 But that concrete is pretty great. Next to water, it’s the most widely used material on Earth. 6 00:00:28,510 --> 00:00:36,700 In the future, concrete may be equally useful off the planet -- when humans construct a permanent base on the moon. 7 00:00:36,720 --> 00:00:41,080 They’ll need sturdy stuff that can weather bombardments from solar radiation and meteorites. 8 00:00:41,100 --> 00:00:44,210 No one wants a crack in their moon base! 9 00:00:44,230 --> 00:00:49,380 The key to making ‘out-of-this-world’ concrete may be to study it … out of this world. 10 00:00:49,400 --> 00:00:55,460 Two experiments have taken place aboard the International Space Station (ISS) to do just that. 11 00:00:55,480 --> 00:01:05,900 The Microgravity Investigation of Cement Solidification (MICS) and Multi-use Variable-g Processing Facility (MVP Cell-05). 12 00:01:05,920 --> 00:01:12,030 Researchers from Pennsylvania State University and NASA’s Marshall Space Flight Center are analyzing the studies’ results. 13 00:01:12,050 --> 00:01:20,320 Concrete is a mixture of sand, gravel, and rocks ‘glued’ together by cement paste made of water and cement powder. 14 00:01:20,340 --> 00:01:26,080 And it’s not as mundane as it looks. Under the surface, it’s quite complex. 15 00:01:26,100 --> 00:01:30,140 What goes on there is key to its strength and durability. 16 00:01:30,160 --> 00:01:35,190 Yet scientists still don’t understand all the details of concrete’s chemistry and microscopic structure. 17 00:01:35,210 --> 00:01:40,570 Processing methods aren’t ‘cast in stone’; there’s plenty of room for improvement. 18 00:01:40,590 --> 00:01:45,740 Aleksandra Radlinska, Principal Investigator for both experiments, says, 19 00:01:45,760 --> 00:01:50,410 “Our experiments are focused on the cement paste that holds the concrete mixture together. 20 00:01:50,430 --> 00:01:58,000 We want to know what grows inside cement-based concrete when there is no gravity driven phenomenon, such as sedimentation.” 21 00:01:58,020 --> 00:02:02,430 It all begins when water is added to the cement. 22 00:02:02,450 --> 00:02:07,510 To put it very simply, the cement’s molecular structure changes when the cement grains dissolve. 23 00:02:07,530 --> 00:02:16,610 Radlinska explains, “As the ‘old’ molecules dissolve, calcium silicate hydrate and calcium hydroxide start to crystalize.” 24 00:02:16,630 --> 00:02:20,200 Myriads of these tiny crystals form all through the mixture, 25 00:02:20,220 --> 00:02:25,210 interlocking with one another and with the other concrete ingredients, such as gravel. 26 00:02:25,230 --> 00:02:30,160 The ISS experiments are researching how this all plays out in space. 27 00:02:30,180 --> 00:02:35,580 Radlinska says, “It could change the distribution of the crystalline microstructure, and ultimately the material properties.” 28 00:02:35,600 --> 00:02:42,160 The ratio of the water/cement powder is critical to making the concrete components combine effectively 29 00:02:42,180 --> 00:02:46,240 and determining the strength and durability of the final concrete. 30 00:02:46,260 --> 00:02:51,380 Will this ratio need to be different on the moon, where gravity is about 1/6th of Earth’s? 31 00:02:51,400 --> 00:02:54,880 That’s the kind of question the experiments will shed light on. 32 00:02:54,900 --> 00:03:02,220 For the MICS experiment, astronauts added water to a series of packets containing dry cement powder, 33 00:03:02,240 --> 00:03:07,120 then added alcohol to some of the packets to stop the hydration process at specified times. 34 00:03:07,140 --> 00:03:11,510 For MVP Cell-05, astronauts also hydrated dry cement, 35 00:03:11,530 --> 00:03:18,360 but for this experiment they used a centrifuge on-board the ISS to simulate gravity at a number of strengths, 36 00:03:18,380 --> 00:03:25,800 including lunar gravity and Martian gravity. For both experiments, the samples were returned to Earth for analysis. 37 00:03:25,820 --> 00:03:29,340 “We’re already seeing and documenting unexpected results,” 38 00:03:29,360 --> 00:03:34,900 says Marshall’s Richard Grugel, co-Principal Investigator for MVP Cell-05. 39 00:03:34,920 --> 00:03:41,030 Radlinska adds, “What we find could lead to improvements in concrete both in space and on Earth. 40 00:03:41,050 --> 00:03:47,480 Since cement is used extensively around the world, even a small improvement could have a tremendous impact.” 41 00:03:47,500 --> 00:03:53,650 We might even end up with better sidewalks for walking our dogs. 42 00:03:53,670 --> 00:04:00,050 For more from the International Space Station, go to www.nasa.gov/iss-science. 43 00:04:00,070 --> 00:04:15,314 For information about other ‘weighty’ matters, visit science.nasa.gov.