Making buil­dings from plant fibres

Bâ­ti­ments en fibres vé­gé­tales

Vocable (Anglais) - - Édito Sommaire -

De nou­veaux ma­té­riaux de construc­tion in­no­vants et non pol­luants.

Pour parer au ré­chauf­fe­ment cli­ma­tique, cher­cheurs et in­dus­triels tentent de­puis quelques an­nées d’éla­bo­rer des dis­po­si­tifs de construc­tion et des ma­té­riaux moins pol­luants, et ils se montrent au­jourd’hui plus créa­tifs que ja­mais... Le plas­tique confec­tion­né à par­tir de fibres de bois et le bé­ton à base de fibres de ca­rottes sont-ils les ma­té­riaux du fu­tur ?

Using car­rots to create con­crete, tur­ning wood in­to plas­tic, or even com­pres­sing it in­to a “su­per wood” that is as light and strong as ti­ta­nium might sound like a se­ries of al­most Fran­ken­stei­nish ex­pe­ri­ments. Yet all three are among the la­test examples of em­ploying na­tu­ral fibres from 1. con­crete bé­ton / to turn sth in­to trans­for­mer qch en / even même / strong ré­sis­tant, ri­gide / to sound like ressembler à / ex­pe­riment ex­pé­rience scien­ti­fique / yet ce­pen­dant, et pour­tant / to be among(st) faire par­tie de, fi­gu­rer par­mi / la­test der­nier (en date), plus ré­cent / plants as eco-friend­ly ad­di­tives or al­ter­na­tives to man-made ma­te­rials.

DOUBLE AD­VAN­TAGE

2. Ma­te­rials-science re­sear­chers are fin­ding that plant fibres can add du­ra­bi­li­ty and strength to sub­stances al­rea­dy used in the construc­tion of buil­dings and in goods that range from toys and fur­ni­ture to cars and air­craft. A big bo­nus is that, be­cause plants lock up car­bon in their struc­ture, using their fibres to make things should mean less car­bon dioxide is emit­ted. The pro­duc­tion of con­crete alone re­pre­sents some 5% of man-made glo­bal CO2 emis­sions, and making 1kg of plas­tic from oil pro­duces 6kg of the green­house gas.

3. Start with the car­rots. These are being in­ves­ti­ga­ted by Mo­ha­med Saa­fi at Lan­cas­ter

eco-friend­ly res­pec­tueux de l'en­vi­ron­ne­ment, éco­lo­gique. 2. goods pro­duits, ar­ticles, biens / to range from... to al­ler de... à / fur­ni­ture (inv.) meubles, mo­bi­lier / air­craft (inv.) avion(s) / bo­nus ici, avan­tage / to lock up conte­nir (sans li­bé­rer), ren­fer­mer / glo­bal mon­dial / oil pé­trole / green­house gas gas à ef­fet de serre. 3. to in­ves­ti­gate ici, étu­dier / Uni­ver­si­ty, in En­gland. Dr Saa­fi and his col­leagues do not use whole car­rots, but ra­ther what they call “na­no­pla­te­lets” that have been ex­trac­ted from car­rots dis­car­ded by su­per­mar­kets or as waste from food­pro­ces­sing fac­to­ries. Su­gar-beet pee­lings are al­so a use­ful source of na­no­pla­te­lets. The re­sear­chers are wor­king with Cel­luComp, a Bri­tish firm that pro­duces such pla­te­lets for in­dus­trial ap­pli­ca­tions, in­clu­ding as an ad­di­tive that helps tou­ghen the sur­face of paint as it dries.

A PO­WER­FUL COM­PO­SITE

4. Each pla­te­let is on­ly a few mil­lionths of a metre across. It consists of a sheet of stiff cel­lu­lose fibres. Al­though the fibres are mi­nute, they are strong. By com­bi­ning pla­te­lets whole en­tier / ra­ther plu­tôt / pla­te­let pla­quette / to dis­card je­ter / waste dé­chets / food pro­ces­sing trans­for­ma­tion ali­men­taire, agro-ali­men­taire / su­gar beet bet­te­rave à sucre / pee­lings épluchures, pe­lures / such ici, de telles / to tou­ghen renforcer, so­li­di­fier, dur­cir / to dry sé­cher. 4. across de dia­mètre/large / sheet feuillet, pla­quette, couche / stiff ri­gide / al­though bien que / mi­nute in­fime, mi­nus­cule /

with other ma­te­rials, a po­wer­ful com­po­site can be pro­du­ced. Dr Saa­fi is mixing the pla­te­lets in­to ce­ment which is made by bur­ning li­mes­tone and clay together at high tem­pe­ra­ture. (The che­mi­cal reac­tion bet­ween them re­leases car­bon dioxide from the li­mes­tone.)

CAR­ROT SOUP FOR STRONGER CON­CRETE

5. To turn ce­ment in­to con­crete, it is mixed with ag­gre­gates such as sand, stones and cru­shed rocks, which act as rein­for­ce­ment, and with wa­ter, which reacts with the che­mi­cals in the ce­ment to form a sub­stance cal­led cal­cium si­li­cate hy­drate. This starts off as a thick gel, but then har­dens in­to a so­lid ma­trix that binds the ag­gre­gates together.

6. By ad­ding ve­ge­table pla­te­lets to the mix, Dr Saa­fi and his col­leagues can make con-

in­to ici, à / li­mes­tone (roche) cal­caire / clay ar­gile / to re­lease li­bé­rer. 5. to crush concas­ser / to act as agir en tant que, ser­vir/faire of­fice de / che­mi­cal sub­stance/com­po­sé chi­mique / thick épais / to har­den se dur­cir/so­li­di­fier / to bind, bound, bound lier. 6. mix mé­lange / to make, made, made ici, rendre / crete stronger. This is use­ful in it­self, but it al­so per­mits a re­duc­tion in the ra­tio of ce­ment to ag­gre­gates that is re­qui­red to achieve a gi­ven le­vel of strength. Re­du­cing the amount of ce­ment in this way conse­quent­ly re­duces CO2 emis­sions.

7. The group is still ex­plo­ring exact­ly how strong it can make con­crete by ad­ding pla­te­lets, but ini­tial stu­dies sug­gest that the im­pact could be consi­de­rable. Just 500 grams of pla­te­lets can re­duce the amount of ce­ment nee­ded to make a cu­bic metre of con­crete by about 40kg—a sa­ving of 10%. Dr Saa­fi and his team have now em­bar­ked on a two-year stu­dy to in­ves­ti­gate the pro­cess in more de­tail and to per­fect the best mix for use by the construc­tion in­dus­try.

WOOD FIBRES IN PLAS­TIC GOODS

8. Un­like ce­ment, wood is al­rea­dy a com­po­site ma­te­rial. It is made of cel­lu­lose fibres em­bed­ded in a ma­trix of li­gnin, an or­ga­nic po­ly­mer that serves a num­ber of pur­poses, in­clu­ding pro­vi­ding woo­dy plants with their ri­gi­di­ty. In May, Sto­ra En­so, a Fin­nish fo­res­try-pro­ducts com­pa­ny, laun­ched a wood-de­ri­ved al­ter­na­tive to oil-ba­sed plas­tics.

9. This ma­te­rial, cal­led Du­raSense, looks a bit like pop­corn. It consists of wood fibres, in­clu­ding li­gnin, ob­tai­ned from pul­ping and other ope­ra­tions. The fibres are mixed with oil-ba­sed po­ly­mers and other ad­di­tives, such as co­lou­ring agents. The re­sul­ting gra­nules can be mel­ted and moul­ded in the same way as plas­tic is in fac­to­ry pro­cesses. Ad­ding wood fibres, the com­pa­ny says, can re­duce the amount of plas­tic nee­ded to make goods with plas­tic parts by 60%. to achieve par­ve­nir à, at­teindre, ob­te­nir / amount quantité / way fa­çon. 7. to ex­plore ici, étu­dier / about en­vi­ron / sa­ving ici, ré­duc­tion / to em­bark on se lan­cer dans, en­ta­mer / pro­cess pro­ces­sus, mé­ca­nisme, fonc­tion­ne­ment. 8. un­like contrai­re­ment à, à la dif­fé­rence de / to be em­bed­ded in être fixé à, faire par­tie in­té­grante de / a num­ber of plu­sieurs / pur­pose fin, uti­li­té / to pro­vide sth with ici, as­su­rer/ga­ran­tir à qch / woo­dy plant plante li­gneuse (dont la struc­ture re­pose prin­ci­pa­le­ment sur le bois) / Fin­nish fin­lan­dais / fo­res­try- ici, dé­ri­vé du bois / to launch lan­cer (sur le mar­ché). 9. to look like ressembler à (vi­suel­le­ment) / to pulp ici, trans­for­mer en pâte / to melt fondre / to mould mou­ler, mo­de­ler, fa­çon­ner / part pièce (dé­ta­chée), com­po­sant.

(Istock)

Plant fibres can add du­ra­bi­li­ty and strength to sub­stances al­rea­dy used in the construc­tion of buil­dings.

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