as our documentary series founders valley is africa to meet the founders empowering their continent through digital innovation transformer, work, and living conditions in their country, and inspiring world with their ideas. only valley africa started february, 13th for b, w. i open your eyes, is everything clear. if so, then perhaps you're still young will be taking a look at how the eyes change as we age. but thus we're digging into the construction industry a major driver of climate change. there are some solutions, like poorest concrete recycled materials and cement from plants.

ah, hello and welcome to to morrow to day the science program on d. w. the construction industry is booming, more is being built around the world than ever before, with serious consequences for the environment. because almost everything is made from concrete containing the binding agent cement. named is made in special kills this combustion process makes it a real climate killer. it's responsible for almost 10 percent of c o. 2 emissions caused by humans, but thus could hopefully change the carbon footprint of concrete could be reduced by using this material. expanded clay small air play balls that are mixed into concrete to reduce its weight. it also

works with glass being their clue about everything about both materials is helping corporate air into a solid structure and the more air the more finally distributed, the better the quality of the i'm so so home in for light concrete contains so much air that it even floats i at the bond is very university and munich. christiane tina's team is testing the formula for their in for light concrete. first expanding clay than water. and finally cement. this mixture weighs less than a quarter of standard concrete because it's so light, the material is harder to work with on construction sites on the team is satisfied

. it is on the i to the special feature of concrete is that it has to flow like a fine chocolate mousse. without the concrete can be used to build walls that provide excellent insulation because of the trapped air digging that one's really cold, right? in for light malls don't need extra insulation like polystyrene. and this concrete also helps the climate in other ways. but it does it because it's porous air containing c o 2 can get inside and then react with the calcium hydroxide in the concrete. so the calcium hydroxide binds the c o 2 from the air and so offset some of the c o 2 that was released during production is utilized before the group, so, and flags it's pulled through. it's open pours the in for light concrete breathes in the greenhouse gas. but the calcium hydroxide contained in the concrete form

during the concrete mixing process absorb c o. 2 from the air. and over the years turns back into calcium carbonate or limestone. and yet the concrete remains stable . i'm using a scanning electron microscope. the research team observes how needles form inside the concrete, interlocking with each other, and providing stability. yes, shawn, we had, we look at how the micro structure has developed. and we can, we see that the strength, building needles, who formed well to produce a highly robust concrete of self at small and magnifications. we can also see the porosity of the micro structure before that there are many more polls. and so much more air is contained in the ultra like concrete than in normal concrete, had as with us from the my, the told him. but how strong is ultra light concrete compared to normal concrete? a block of regular concrete is exposed to pressure

at the break, but only under 60 tons of pressure. when it's the turn of ultra light concrete, it breaks under just 9 tons of pressure. this is the ultralight, concrete, has a stronger overall structure than standard bricks are, is highly robust. as you can see from the way it to performs under stress for form, you can use this concrete in an earthquake zone. it still has half of its load bearing capacity even though it's totally broken with tarka put us. this is enough for a standard house as close down tino, but not for bridges or skyscrapers. ah, old buildings are often demolished to make way for me once. but what happens to the

old building materials most of the time they're disposed of, but almost all the components of a demolish building can be recycled. this may significantly reduce the carbon footprint of the construction industry. in berlin, sure. in a back district, this student presidents has long stood empty. now the old building is set to become something new, a multi generational house, thanks to annabel fund whiten. lot of as a typically it would just be torn down this week. exactly. that's why we're happy you're here. so we can go through the building together and see what parts can be kept and we used. the aim is to save resources, reusing something avoids having to produce it all over again. it reduces c o 2 emissions but requires more planning. that's good as us. in fact,

the good thing is that compared to the much than a granite lamps that were used the loss in the 1990s, the smaller to rat. so tiles are about 4 centimeters thick and they can believe it out quite easily. all saving come on above annoyed on is an urban mining expert for her sites set for demolition. our sources of raw materials for new building projects. the sense done is live, wind is in the problem is often that use energy saving regulation is that certain ones can no longer believe they simply can't me. today's standards used building materials can't always be re used in their original form at he seems like glue or mortar make for added complications. but the material must be removed, re cleaned and hauled away, which requires more work and often a rethink during planning. at the calls were institute of technology professor dia

cable teaches butting architects about circular construction. he's been monitoring sustainability in the building trade for over 2 decades to help me with it's not yet seen. so in recent decades, if not centuries, yada, we followed a linear business model name. that means we extract materials from the earth's crust to produce things like buildings. then we demolish them and deposit the materials as waste and landfills, diesel thing this way of thinking must change in the future of diet at 1st because resources will be in shorter supply. doyenne and 2nd, to take responsibility and protect the climate better martyrs. to think circular wouldn't and no longer follow this linear model that's led us to a dead end. denise, what it does, once in the suckers shouldn't switzerland is a pioneer when it comes to resource efficient construction. in basel, they're even considering of voluntary commitment to using recycled building materials, architect, caston. miller and her colleagues have already realised numerous innovative

buildings this way, often unsightly and for. we need some advance warning about buildings that are about to be torn down. simply said that we can go there early enough, then we have the time to evaluate the construction component and save them so that we'll get to evolution for a current project, they're salvaging tons of electricity, pylons they are real climate killers, to produce recycling the steel supports allows the architects to reduce c o 2 emissions during the entire production process, the macand as male male into name. we're noticing that more and more companies are adopting this concept and making the hugs as get at 1st, they're quite skeptical and only see the problems and huddles i. but as soon as they've done it once have been through the process, they view it as an opportunity to position themselves from the market and carry it further toxins. it wasn't as tough as it looks at 1st. you some on from shined. one of the architecture firms biggest projects is the cups bow holler in the city of

vintage to 70 percent of the building was made from repurposed materials, young outdoor clint, that we learned from it that you need a launch platform, felice. construction materials. i be folic as they come in at different time, and you need an interim storage facility to prepare them for a specific building and pow such an internet platform as being developed in berlin called consular. it creates so called material passports, which include a materials age, condition, shape, and color. they're then posted online. when a property developer finds a component, they can use a matches made soon. it could become even easier if the stands are fastened. the inventory that we're doing now is necessary because there aren't any material possible as yet if in future such passports, why required for every new project on the controller platform that just have to be activated at the right time. i should have been assessing which materials can be

recycled and whether it's worth the effort requires experience and know how the architects know that some materials are more popular on the 2nd hand market than others. steel is sought after other materials, much less so, and it's too costly to recover and transport materials just to have them sit in storage. there are other hurdles to regulations about warranties and liability when employing used. building materials still need to be established in germany. sustainable construction requires more than just the will of architects and builders. it also requires a legal framework. now, as we got mostly doing isn't just nice to have, it's the future. we must plan and build this way. although be new construction revolution. and without that, no climate revolution, we won't meet the 1.5 degrees target if we don't radically changed the construction industry. so in the near future, the architects 1st job could be c would construction materials are available on

this circular marketplace and plan accordingly. concrete can also be recycled and if it can, it should be because the manufacturing process is extremely climate damaging concrete as might have water, sand, gravel and cement. ah, the cement itself is composed of limestone and clay. it's kiln fired at up to $1450.00 degrees celsius. one of the most climate damaging stages of production. the combustion process requires enormous amounts of energy and releases carbon dioxide. c o 2 is also released in the chemical reaction. when limestone, c, a, c o 3 becomes quick, lime c, a o, and c o 2 ave alternative ways to make some main production more environmentally friendly. could

there be huge potential locked away in the humble cassava materials researcher voice thumb. schmidt wants to use it as raw material for cement and use it to produce high quality concrete. cassava, also known as manioc, or euchre, is a starchy tuber. grown is food and many countries, but the peel is poisonous, which can cause problems when it rots. we're working on a little we're, we're making a form of cement from the ash of cassava pio and water is on. we would later add sand to make it into something like concrete at all. this was like a precursor to concrete. we want to see if we can get the same properties from cassava. peel, ash that we can from the normal cement to mixtures. linesmen in the middle, schmidt's concrete does contain some cement, but also the ash of cassava, peel,

and sand and gravel like normal concrete. schmidt fern, the cassava appeal to ash, and then placed it in a kiln pip, almost $800.00 degrees celsius. this releases a substance that's contained in the peel silicon dioxide. and that's the key to smith's concrete when the song of so now it's time for the sand and we've got course medium and fine saplings and we'll pour that all in together now. and then the cement and water and finally, the cassava ash, with the silicon dioxide we've, on your chart, isn't sold on the cassava. peel is also used for cleaning more so in places word grows allotted, which makes sense,

like sierra leone and gonna stick with often with a highland is the biggest exporter of cassava, and huge amounts of it. grown brazil out among their they call it yoko or mun joker . thought was this an apple to see those of the country grows way more than it eats all. so there's a lot left over that could be used to make some antigen dollars to manufacture false. lum. schmidt's research calling in nigeria are already experimenting with cassava. ash. the technology is improvised by effective simple ovens are used to produce the ash. the cement alternative is already being successfully produced and large quantities listed here. so this is murphy, i was issued, it's important that the material flows nicely. it but that the air bubbles can escape by themselves. they're not trapped because that would reduce the strength of

the concrete. the i'm, his issue in the contents of life is not. this is a nice consistency. it flows but it's stable, will be partakers in initial from wouldn't even the course particles don't sink to the bottom. we've made some good concrete here that only has 50 percent of the normal cement content by replacing it with limestone powder and could solve appeal ash, which as hello, shine ocean, half as much cement as normal means lower c o 2 emissions vol. sam schmidt wants to use test blocks like this to demonstrate its strength. the concrete is put under pressure until it breaks and it manages to withstand the same load as normal concrete. this pavilion at lake os university and nigeria is made of cassava concrete, a solid,

new eco friendly alternative in construction. if i'm a blood is red, why i? and now over to you, what have you always wanted to know? if you had the question about science nature, technology all makes and then just ask if we answer it on the show, we'll send you a little surprise as a thank you right. oh, send a video message to tomorrow to day at d. w dot come this next question comes from wilberforce. nixon in nigeria. oh, how long can a person survive without eating fasting or freely choosing to go without food is a common custom around the world. people up to fax for a certain time for religious health or political reasons. but how

long a person can survive without eating depends on many factors. the amount of fact reserves they have, their age and general health, all play an important role. someone who stops eating and drinking will die within a matter of days. those who go without food but stay hydrated will live longer. for the 1st days, the body goes without food. it draws on its blood sugar reserves, mainly to keep the brain functioning because that requires a lot of glucose under normal circumstances. around half of our daily glucose requirement is consumed by the brain. but if there's no more sugar intake, the brain secures all of the glucose reserves, leaving the rest of the body to go hungry. once the glucose is gone, protein is next. the body starts to break down muscle. it turns amino acids

components of muscle proteins into glucose. jermaine chain supplies to the brain, but the body also burns fat until all gone tooth. o, starvation mode begins. bodily functions gradually shut down the heart rate, blood pressure, and body temperature all sink the body does everything to reduce the amount of calories that burns in order to conserve energy. that can prove dangerous for children in particular. like here in the horn of africa, children's bodies react much quicker to mound nutrition. they can starve to death as a result of long periods of drought and failed harvests. if there is no more energy left in the muscles, the body starts to draw on its own organs, which can shrink to half their former size as a result. because the heart muscle is also broken down,

starving people often die of heart failure. ah, scientists figure that people can survive for 2 to 3 months without eating, but going without food for so long results in lasting damage including a weakened immune system, as well as major muscle and memory loss. and now why our vision declines as we become older, usually this happens to adults in the mid forty's. the eyes, accommodation 2 objects near or far away becomes limited. seen, clear without correcting lenses, depends increasingly on light and visibility conditions. but why? what happens? we're about to find out starting with a popular children's game that requires the keen eye is

their eyes by with my eyes, isn't i that something that is red? this is child's play for 10 year old emily whose eyes see colors brightly and details sharply, but not for her grandma. the game leaves her looking old. i tell you is over there. but why is that? what happens to our eyes as we age emily's? grandma ingrid noticed the 1st changes in her early forties ever since she is increasingly had trouble seeing things clearly up close. a classic case of pres, bio, pia, or age related farsightedness. many think the i muscles, it's a blame, but ophthalmologist antonia chuckle off has more insight. 9 has to be the lens. that's the problem. it gets harder and less flexible as we age. and so the accommodation, the close up focusing no longer works is perform. i'm still only mccloud from

lanier. during childhood, the lens is still elastic, allowing it to bend to vary the refraction over the years. this ability termed accommodation is lost as the lens harden's, the muscle has a tough a time reshaping it, especially up close. the refraction isn't sufficient to focus light precisely on the retina. the image becomes blurred. so emily's grandma keeps her reading glasses at hand. it's an easy way to rectify the problem. yeah, yes, i've got one. up to me too. ok, great. but that's not ingrid's only problem. objects in the distance are also blurry, and sometimes everything's foggy. and a few rays of sunshine can make her eyes water. that's due to the lenses to children's are still transparent and clear. but over the course of our lifetimes,

certain proteins inside the lenses start to clump together. as a result, they get claudia, causing some of the light to diffuse and become glaring. the image on the retina then appears to be blurry or foggy. of any done with him can ha, ha ha. this clouding of the lens of the i is known as a cataract is in business for the examination of ingrid's. eyes shows that she have the mild cataract, but it's not problematic yet. dylan, kent's rights are enormous sign of aging, they only become problematic on require surgery if they lead to subjective impairments of vision for people bless the inability to distinguish colors or contrasts. there's farms instance compress infants foot the changes occur gradually . simenon, can you give me a light blue m. o. been even a mild cataract means colors dominic as bright to her grandmother,

then denied that the dog named to her white looks yellowish and shades of blue, a launch li filtered out of the t closer. the classic problem is that patients dress strangely as they no longer recognize the colors in that closet. clarifying, although washed the drapes constantly because they look so yellow look at a time. but what worries ingrid far more is not being able to see well in the dark . she can no longer distinguish between slight differences in brightness, which poses a danger while driving. several factors come together to produce what's known as night blindness. first, the cloudy lens absorbs a lot of light, but the retina also shows signs of aging and isn't as well supplied with blood and nutrients. over time,

around 30 percent of its photo receptions die above all the rods that are responsible for night vision. it doesn't make for a rosy outlook. mckenzie aldo from a 3rd of the light sensitivity of young people, you mention. but isn't there a way of turning back the clock, or at least slowing it down? there's no secret recipe to stop eyes from aging, though, eating lots of fruit and vegetable certainly can't hurt. bit him in a and other carotid noises like lutin, which is found in leafy greens, are central the good eye health. otherwise the best advice is to avoid risk factors . kotik house down to racks can be triggered or worse and by over exposure to the sun's rays and heavy smoking or otherwise, there's not really much you can do on the scope it naturally. a healthy diet is always good and a healthy lifestyle over all because on the limbs, pfizer and scott. and that includes uv protection from

a young age. but even the best precautions can't stop the eyes normal aging process . so old eyes don't stand a chance against young ones you see, and i fight with my that lie wise emily and how grandma might soon have to find a different game to play that. so for this edition of tomorrow to day, thanks for joining us. and see you next time. until then stay curious. ah ah, ah, with

who? the 77 percent. i always wanted to be a farmer, but i can't imagine doing it anywhere else. but at home. why or young africans returning home from abroad? we'd be sending the rest the week of july,

things about home office. and when you come back yet, can we have it? we'll chat. the 77 percent in 30 minute spawn d w o a is increasing every year many im gonna working on landfills and we work very holiday destinations drowning in plastic white we we wine and take a look at the causal every year bureau that exports over $1000000.00 tons of plastic with use there. another way. after all, the environment isn't to recyclable. make up your own mind. d. w. made for mines. o mania.

i am said lana seattle's tie. i am running for president of the republic of bella rose, leaky ah, like every one else, is it for a long time i thought it was best not to get involved in politics in hugh, she is a wife of an upcoming politician in a dictatorship and then in a moment where she tries to stand up for her husbands, who destiny changes and she, herself becomes a school teacher. type jun dark searches for the truth again. this time, the exile to turkish journalist meets svetlana itsyana, sky up exiled leader of the opposition and beller roost. of course, i'm tired. i'm tired. physically untied, morally is too much on my shoulders, but i have to hold this way because i'm responsible for the future. follow contra

for the people far behind the boss. gardens of truth starts february 18th o d, w ah ah, this is the w news live from berlin, the your secretary of state heads to the middle east, amid the latest outbreak of violence between israelis and palestinians. onto me, blanket told me to drive the prime minister benjamin netanyahu following a palestinian attack on a stomach off with careless happened with deadly israeli right on the left back also on the.