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Sticky Rice Is the Key To Super Strong Mortar 194

lilbridge writes "For over 1,500 years the Chinese have been using sticky rice as an ingredient in mortar, which has resulted in super strong buildings, many of which are still standing after hundreds of years. Scientists have been studying the sticky rice and lime mortar to unlock the secrets of its strength, and have just determined the secret ingredient that makes the mortar more stable and stronger. The scientists have also concluded that this mixture is the most appropriate for restoration of ancient and historic buildings, which means it is probably also appropriate for new construction as well."
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Sticky Rice Is the Key To Super Strong Mortar

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  • Two more (Score:5, Funny)

    by qortra ( 591818 ) on Wednesday June 02, 2010 @04:10PM (#32436594)
    Based on experiences with my dishwasher, I can also predict that buildings made with oatmeal or cheese will also stand the test of time.
    • by DeadDecoy ( 877617 ) on Wednesday June 02, 2010 @04:31PM (#32436882)
      you'll shit bricks.
    • Re: (Score:3, Informative)

      by mcgrew ( 92797 ) *

      Or potatos. Do NOT put potatos down your garbage disposal; I found that out the hard way. Had to rent an electric plumber's snake to unplug the damned drain. The disposal has no problems, it's after they go down the drain and harden.

      • Re:Two more (Score:5, Informative)

        by IndustrialComplex ( 975015 ) on Wednesday June 02, 2010 @04:59PM (#32437230)

        Or potatos. Do NOT put potatos down your garbage disposal; I found that out the hard way. Had to rent an electric plumber's snake to unplug the damned drain. The disposal has no problems, it's after they go down the drain and harden.

        It's ok Dan, you can use 'Es' this time.

        But on a serious note, you were essentially putting one half of a binary glue down your drain. The other part of that binary product is water which your disposal kindly mixed for you. []

        • That, is some seriously awesome thing to know. It makes so much sense too, if you think about the last time you made pasta...

          No more Scotch tape for me!

      • by nizo ( 81281 ) *

        I recently had a problem with my disposal, but it was just the peels that did it.

      • by tsm_sf ( 545316 )
        Garbage disposals really aren't that great of an idea. Job security for plumbers, basically.
    • Re:Two more (Score:5, Interesting)

      by timeOday ( 582209 ) on Wednesday June 02, 2010 @04:40PM (#32437002)
      Rice is pretty strong. My wife once dumped a partially-cooked pot of rice down the kitchen sink, where it proceeded to swell up to an impenetrable clog. Being a fool, I got a plunger and just kept at it with increasing force until the all the water (and drano) that had pooled up, suddenly went right down the drain - and straight into the cupboard, because I'd knocked the rice-cemented plumbing right off the bottom of the sink.
      • For organic matter you're frequently better off using enzymes or bacteria to deal with slow drains than chemicals. Although in this case I doubt that would've done much good as you generally need some water flow in order for it to work properly.
        • Re: (Score:3, Funny)

          by Pharmboy ( 216950 )

          In this instance what he needed was a bucket and a new "P" trap. Or at least a bucket and a chisel, to remove the cemented rice. I have had plenty of maintenance men say that rice kills pipes.

          Raw rice isn't too good for birds either as they tend to eat, drink, expand & explode. Similar to pitching a seagull an Alka Seltzer, only in slow motion. This is why the tradition was changed to throw bird seed.

          • Re:Two more (Score:5, Informative)

            by eclectus ( 209883 ) on Wednesday June 02, 2010 @07:26PM (#32438814) Homepage

            The 'feeding rice to birds will make them swell up & explode' is a myth. snopes even says so.


            • Wow, I stand corrected. Then why is bird feed better than rice? Hmm...

              • by Moryath ( 553296 )

                Easy to answer - RICE GOT EXPENSIVE. Time was, rice was cheap and plentiful, so people threw rice. After the expansion of the corn lobby in the USA, a lot of farmers (many in areas that are shit-stupid to grow corn in) switched over to corn, and so there was a lot less rice available. Price went up for rice, price went down (thanks to wasteful subsidy $$$$ for way too fucking much corn than we can properly use), and people went looking for an alternative to toss at weddings. That's also when the stoners cam

      • Maybe that's what BP should do to the oil well... dump a lot of pots of half-cooked rice down it :)
        • well, seeing as they have tried just about everything else (and given each try an absurd name), it may be worth a shot. Call it 'operation stir fry kill'
          • Operation Cold Porridge. And then when that fails, their second try will be Operation Cold Porridge 2: Lumpy Chunks.
      • Re:Two more (Score:5, Funny)

        by nigelo ( 30096 ) on Wednesday June 02, 2010 @05:16PM (#32437412)

        The other favourite is to carefully capture the dirty water in a bucket when disconnecting the drain, stand up, then think: 'where can I lose this? I know! Down the drain...' Wet feet.

        • by aXis100 ( 690904 )

          Hehe. Glad I'm not the only one.

        • Re:Two more (Score:4, Funny)

          by russ1337 ( 938915 ) on Thursday June 03, 2010 @01:35AM (#32441086)
          while living in Military barracks we had single rooms each with a sink and cupboard against one wall. It was a common prank to disconnect the drain in a buddies room while he was out drinking, because you *knew* he was going to piss in it during the night instead of walking all the way down to the toilets.

          the thought process is excellent: ahhh..... wait why are my feet wet! no no no ... can't stop!....ahh f&K it....
  • by Colin Smith ( 2679 ) on Wednesday June 02, 2010 @04:10PM (#32436596)

    Many of which are still standing, 2000 years later.

    I predict the common factor may be the concrete.


    • Re: (Score:3, Interesting)

      Tell that to the idiots who build the building I am working in in the 70s - concrete, and nothing but concrete. It is crumbling now. Yay for engineering efforts...
      • by Chris Mattern ( 191822 ) on Wednesday June 02, 2010 @04:21PM (#32436754)

        There are people who know how to do concrete right. And then there are people who know how to do concrete cheap.

      • by zygotic mitosis ( 833691 ) on Wednesday June 02, 2010 @04:23PM (#32436764)
        You're working in the 70s? Aren't wages much lower? Why don't you invest in Apple, Microsoft, or IBM instead?
        • You're working in the 70s?

          Yes... Internet connections were *very* slow back then. That's why his message took around 35 years to reach Slashdot. In fact, he was very insightful, as Slashdot wouldn't be invented for almost another quarter century.

        • by treeves ( 963993 )
          He's working in *his* 70's. His memory falters from time to time. Give him a break.
      • by ElectricTurtle ( 1171201 ) on Wednesday June 02, 2010 @04:29PM (#32436854)
        You're sure there's no rebar, no iron at all? I doubt it. It's the iron inside the concrete that contributes to its decay, because the metal expands and contracts with seasonal changes in temperature. Concrete without iron in it may be structurally weaker, but it will last a lot longer if kept within proper parameters for loads. (Hence why the Romans' stuff is still around.)
        • Yes, of course there is rebar - the point I was trying to make is that concrete as such is not the common factor, it is how you treat the concrete, it is what you add to it. On the current topic - the rice might actually be an interesting factor. I was just trying to load off some snark on the "ohh, it is the concrete, stupid scientists"-crap posted above.
          • by Maxo-Texas ( 864189 ) on Wednesday June 02, 2010 @05:08PM (#32437322)

            It wasn't until the 80's or 90's that romans use of fly ash became common knowledge. Back in the 70's, roman concrete was still in the "ancient mysteries" column.

            • Re: (Score:3, Interesting)

              by Anonymous Coward

              Just a piece of concrete-nerd pedantry: The Romans didn't use fly ash - that comes from coal-fired electricity generation, which I'm reasonably sure they hadn't invented yet. It was volcanic ash, "pozzolana". Similar chemistry, but made in a volcano instead of a coal boiler.

        • by need4mospd ( 1146215 ) on Wednesday June 02, 2010 @05:19PM (#32437460)

          It's the iron inside the concrete that contributes to its decay, because the metal expands and contracts with seasonal changes in temperature.

          Uh, so does concrete. Actually, they expand and contract at nearly the same exact rate depending on the composition of the steel and concrete. Without the steel you'd need a ridiculous amount of concrete to make up for it because concrete has a lower tensile strength. Adding enough concrete to make it work properly would make concrete structures very bulky and would limit their height considerably.

          (Hence why the Romans' stuff is still around.)

          The Roman stuff is still around because it was VERY thick, not because it didn't have steel. It probably would be in significantly better shape if they used steel.

          • "Nearly" is the operative word here. Repeat a 'near' difference 2000 times and tell me how inconsequential it is, especially when it comes to shifting the weight of a structure over and over again.
            • Re: (Score:3, Informative)

              by need4mospd ( 1146215 )

              "Nearly" is the operative word here. Repeat a 'near' difference 2000 times and tell me how inconsequential it is, especially when it comes to shifting the weight of a structure over and over again.

              That's not really how it works. After the concrete cures the concrete and steel are at a sort of equilibrium. Whenever the structure is at or close to that temperature, everything is peachy. It's at extreme temperatures when you start to see expansion(or contraction). The coefficient of thermal expansion for concrete and steel are not only very close, they are extremely low. Meaning you'd need un-earthly variations before you'd see any detectable amount of variation.

              • Also note that the steel is elastic. It will give to make up for the slight difference in the coefficients of thermal expansion.

              • thank you. if I had mod points i'd mod you up. informative probably.
              • Re: (Score:3, Insightful)

                That equilibrium is not perfect. The difference does stress and wear the structure over decades, centuries, millennia, especially in temperate zones where temperature can vary more than 100 degrees a year. Like I say, repeat that for 2000 years and see what things look like. You're right, the difference is very low, but when you're talking about really large structures over really long periods, ANY difference is significant. In that scenario, solid concrete stands a better chance, so long as it's not overlo
              • by CAIMLAS ( 41445 )

                Also, Rome is in a pretty moderate climate: the temperature and humidity does not vary much throughout any given year. Compare this to conditions in, say, the Northeast US, Northern Europe, or even the Western US: the temperature varies significantly, and there is notably more moisture throughout the year - which will seep into the cement and contribute to its decay.

            • As has been already stated, the concrete and steel bond and do expand and contract at the same rate. Additionally, the pH of the concrete is what prevents the steel from rusting. Usually. This is why they will throw crappy, rusted rebar into the mix, as it won't matter as soon as it sets up.

              • Re: (Score:3, Informative)

                by John Hasler ( 414242 )

                > This is why they will throw crappy, rusted rebar into the mix, as it won't
                > matter as soon as it sets up.

                They use rusty rebar intentionally. Concrete bonds well to rusty steel.

          • I dunno... Build another "largest unsupported concrete dome" but with with rebar and we'll talk.. in two thousand years...

        • So that's why there aren't any Roman toilets around anymore. They couldn't handle the load.

        • These days fiber is the way to go.

          Concrete with fiber in it is good and strong, and in my experience (dad pours concrete for a living) it cracks less than concrete without.

      • Would you really want it to last 2000 years?

        Take Cumbernauld as an example. Very definitely not.

        Which is another thing. Concrete doesn't have to be ugly. So WTF are so many modern concrete buildings so god damned ugly? []


    • by jgagnon ( 1663075 ) on Wednesday June 02, 2010 @04:14PM (#32436646)

      Water is also a common ingredient. Hmmm... :p

    • by SgtChaireBourne ( 457691 ) on Wednesday June 02, 2010 @04:32PM (#32436886) Homepage
      One additive that gives strength to concrete the Roman built with is blood []. It doesn't have to be human blood. Funny how the quality of concrete and steel deteriorated during the period 1200 - 1500. I wonder what could have been going on in Europe then. ;) Blood still works well, but does tend to tint the material pinkish or reddish for a long time.
    • Re: (Score:3, Informative)

      by EggyToast ( 858951 )
      This isn't concrete -- it's lime mortar (which isn't used anymore). This is just a very hard lime mortar due to the additives -- it doesn't give any strength comparisons to portland cement. I imagine it's significantly less strong, though, despite the headline. This is "super strong" compared to plain ol' lime mortar.
    • by sjames ( 1099 )

      It's not that all of Rome had a great secret we don't know, it's just that the many less successful mixes are long gone without a trace.

      The particular mixes used in the buildings that are still standing would be worth studying.

  • Amylopectin (Score:5, Informative)

    by Verdatum ( 1257828 ) on Wednesday June 02, 2010 @04:12PM (#32436620)
    I didn't know the critical ingredient was a mystery. Alton Brown from Good Eats explained the molecule quite well in the rice episode, and my immediate thought was "oh that must be why it was used in mortar for the Great Wall and such."
    • Re:Amylopectin (Score:5, Informative)

      by EggyToast ( 858951 ) on Wednesday June 02, 2010 @04:53PM (#32437166) Homepage
      Thing is, lime mortar hasn't really been used for about 150 years, so there's no research into it for modern building applications. Since OPC is better in every regard, including strength, repairing old lime mortar hasn't really been of concern until recently, when there's been more of a push to accurately repair historical buildings and structures. However, you're not exactly right with the Great Wall -- it was built 2200 years ago, whereas TFA notes that this particular process was done 1500 years ago.

      Still, I imagine this was also prevalent in Pre-Columbian architecture too, only with corn. Boil the corn, then use the leftover water.
      • Re: (Score:2, Informative)

        by serbanp ( 139486 )

        However, you're not exactly right with the Great Wall -- it was built 2200 years ago, whereas TFA notes that this particular process was done 1500 years ago. .

        ugh, the Great Wall was nominally finished during the Ming dynasty, in the 1400s. Unlike the oldest sections, built with rammed soil and stone, the more modern parts did use bricks and mortar.

    • Re:Amylopectin (Score:5, Informative)

      by rritterson ( 588983 ) on Wednesday June 02, 2010 @04:53PM (#32437170)

      From reading the physorg summary linked in the article linked in the summary on Slashdot (why we have to link to tertiary sources, I don't know) it seems that it isn't the polymer branching of the molecule that lends the mortar strength- the amylopectin doesn't even directly add strength as far as I can tell. Instead, it's that the amylopectin breaks up the crystallization of the lime in the mortar, creating micro crystals instead. I can imagine a big crystal being quite brittle with all of the possible shear planes.

      So, it wasn't as obvious to me why the amylopectin made it stronger.

  • Sounds like (Score:5, Funny)

    by 0100010001010011 ( 652467 ) on Wednesday June 02, 2010 @04:12PM (#32436624)

    Ancient Chinese Secret

  • Er, do we have such an overabundance of rice that it can be pressed into use as a building material?

    • Re: (Score:3, Funny)

      by Yvan256 ( 722131 )

      Exactly! Rice doesn't grow on trees, you know!

      • Re: (Score:3, Funny)

        by jgagnon ( 1663075 )

        Someone might be able to make a genetically modified version that grows on walls. That would be cool.

    • Re: (Score:3, Informative)

      by somersault ( 912633 )

      China probably does.. I mean sure it has a billion people, but apparently it produces 25% of the world's rice.

    • Re: (Score:3, Interesting)

      Yeah, it is not like it grows in trees...

      One main advantage is that it is easier to replenish than minerals. You can grow a field of rice, collect it and then grow it again next year. If you get a mineral (v.g. carbon) from a mine, the next year your only chance to get more carbon is to dig further. Also it helps capturing CO2 from air instead of adding into it.

      DISCLAIMER1: I know rice is a plant but not a tree.

      DISCLAIMER2: I am not saying that this mortar has no disavantages (old buildings may have surviv

      • by cynyr ( 703126 )
        i wonder what the R value on the thicker walls is, and if it is cheaper per foot of wall? even if you have to make it longer to get the same inside space, it could be cheaper and more insulating.
    • by Jeng ( 926980 ) on Wednesday June 02, 2010 @04:26PM (#32436816)

      Yes, we do have enough rice.

      We have enough food production that no one should go hungry.

      People go hungry due to politics and poor distribution, not overall quantity of food.

      • Re: (Score:3, Informative)

        by camperdave ( 969942 )
        People go hungry due to politics and poor distribution, not overall quantity of food.

        Actually, we have the capacity to deal with poor distribution as well, so it all boils down to politics. Someone is deciding that people should starve to death.
    • Re: (Score:3, Interesting)

      by EggyToast ( 858951 )
      We could, but it doesn't matter -- we don't use lime mortar anymore. We use portland cement.
    • As soon as Monsanto works out how to create GMO corn that produces amylopectin, we'll be all set to use it in America!

  • by Joe The Dragon ( 967727 ) on Wednesday June 02, 2010 @04:15PM (#32436658)

    sounds like a job for the MythBusters!

  • by tacarat ( 696339 ) on Wednesday June 02, 2010 @04:16PM (#32436668) Journal
    So is this a good time to invest in California calrose growers?
  • by AngryNick ( 891056 ) on Wednesday June 02, 2010 @04:41PM (#32437010) Homepage Journal
    ...provide this information to BP?
  • According to the gas chromatograph, the secret ingredient in Chinese construction is... Love!? Who's been screwing with this thing?

  • What is the effective range, and what calibre projectiles does it fire?

    Can it be equipped with smart munitions? I hear they have even developed anti-tank rounds for 81mm and 120mm mortars.

  • by drwho ( 4190 ) on Wednesday June 02, 2010 @07:13PM (#32438682) Homepage Journal

    Mortar that's too strong is brittle, meaning it can easily crack. Rebar can rust and swell, breaking this brittle cement. The result is catastrophic. I learned this from a couple of masons who I was drinking with at a pub. They joke that because of some really bad decisions made by architects and structural engineers in the 1960s and 1970s, they have good job security. I had known from reading books on restoring historical masonry buildings (thanks Ian Cramb) that strong mortar such as portland cement and other more modern mixes are just too brittle to be used as mortar. Stones and bricks shift ever so slightly as they settle. This can cause cracks, large or small, in the brittle mortar, that wouldn't happen with a weak lime mortar. These cracks are the widened by water freezing and thawing, and sometimes plant life. But what my bar buddies told me is that what makes the problem even worse is the rebar used in concrete buildings until recently would slowly rust and swell, so the masonry would burst from the inside because it was so brittle. These mason fellows would chip out the remaining concrete or cement, clean and coat the rebar (but sometimes replacing it) with a protecting paint, and then re-apply cement or concrete. I've noticed this problem occuring in many places, such as subway stations and bridges in the Boston area. I have no reason to believe the problem is limited to this city.

    Regarding Roman cements and concrete: pozzolana, otherwise known as hydraulic cement, was a mixture containing volcanic ash, specifically from mount Vensuvius. It has the ability to dry and set underwater. This 'secret' is said by many to have been lost for many centuries, but in fact was kept a 'masonic secret' by some masonic guilds for a long time. Yet the exact nature of this secret and its revelation are hazy.

    Yes, blood was used as an ad-mixture to some Roman cements. I can't remember what benefit it added.

    Some places add organic material to concrete, with a variety of results. Done correctly, it increases the strength of concrete. Done badly, it's a recepie for disaster. Using straw is certainly bad, but evidently hemp and possibly other materials can be used. Exactly what works under given conditions is not known to me. It may be another one of the 'masonic' secrets.

    • by rahvin112 ( 446269 ) on Thursday June 03, 2010 @02:28AM (#32441404)

      Epoxy coating the re-bar has not been proven effective. What the masons you had a beer with is typical of the trades, they don't understand the big picture because they are focused on their job. No engineers or architects screwed up (other than the very few public examples of failure). Buildings are designed for a certain life, typically that's 50-70 years and after that the building is expected to need capital investment in the infrastructure beyond routine maintenance to extend that life. Buildings could easily be designed to last longer but the longer the life the higher the cost and it's rare for an owner to care. Buildings could easily be designed to take fires, earthquakes, tornado's and hurricanes but the costs of such design make it illogical.

      The masons you mentioned talked about paint, it's not paint it's epoxy and it's a highly unproven technology (unless you are talking to the epoxy association, then it's the end all be all of re-bar protection). There are some in the engineering sector that think Epoxy coating re-bar is going to be one of those big mistakes that comes back and haunts us endlessly in a few decades (epoxy coated steel has been in use since the late 80's). The thing is concrete by itself is highly alkaline, the steel itself is alkaline as well and this prevents corrosion (which needs acidic environments to thrive, remember it's an oxidation process). The problem with epoxy is it negates the alkalinity effect of the concrete. In a perfect world the epoxy would be clean and perfect after the concrete sets but in reality the epoxy is going to have abrasions and cuts from erection, pouring and finishing (not counting what a decade of thermal expansion does to it). These abrasions in the epoxy coat provide a path of corrosion and once it penetrates the abrasion and infects the steel it can move along the steel much quicker because of the epoxy coat protecting the corrosion from alkalinity of the concrete. IMO a much better solution is galvanizing, the zinc coating has an additional alkaline protection and is much more durable during construction than epoxy ever can be. Either that or use high ksi stainless steel.

      Boston is not alone in problems with re-bar corrosion, the issue involves the use of salt, cities and states that use salt in the winter on the roads, the salt provides the corrosion path and negates the alkalinity resulting in corrosion way ahead of schedule. The salt on the road moves through the environment and affects lots of ancillary structures including nearby buildings and tunnels. Black-bar re-bar used in concrete where salt isn't applied, even underwater and in freeze/thaw cycles has been very durable. There is reinforced concrete out there that is still in perfect shape that was poured 50 years ago and it's harder than ever.

      Also, all concrete sets underwater, concrete doesn't dry, it hardens, it is a chemical reaction that involves hydration and the formation of a crystalline structure using the water. Without water there isn't concrete or if you allow the concrete to "dry" before it sets will degrade the concrete severely. This is why they have to keep the concrete moist for several days after pouring. Premature drying has similar symptoms to over-finishing, the surface of the concrete spalls the top surface off after a time rusulting in the loss of about a 1/4 - 1 inch of concrete on the surface spalling off.

      And finally, organic additives to concrete are NEVER a good thing. Organics deteriorate after time, this leaves voids in the concrete where the organics ended up and the decay can create acids and bases that can adversely affect the concrete. Organics are bad, period. Now, Roman use of organics, such as blood may have resulted in more air-entrainment. The little tiny air-bubbles formed after the organics decayed (or as a result of mixing them in) would have provided freeze-thaw protection. Concrete placed in the open weather typically needs ~5% air entrainment to eliminate the effect of water saturation and freeze/thaw cycles. The heavy use of

    • by klui ( 457783 )
      I made the mistake of using hot water to soak a blood stained cloth and now the stain will not come out. My wife told me that cold water should be used to wash it because hot water will cook the protein in the blood. Now the stain--not bright red, but much faded but is still visible--is in the form of a crusty texture. Maybe blood can act as a binding agent or something like that and the curing concrete is used to cook it?
  • TFA says that the rice additive has been used since the Ming Dynasty... and then goes on to say 1500 years ago. Ming Dynasty ruled around 1500 AD. They got themselves a 1000 year discrepancy there. Would sure be nice if they were more accurate about what they meant.

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