Ce­ment poser

The Star Malaysia - Star2 - - ECOWATCH -

CON­CRETE is the most preva­lent build­ing ma­te­rial on the planet and the world would be pretty flat, with no tall build­ings and struc­tures, with­out it. But no con­struc­tion ma­te­rial is more eco­log­i­cally de­struc­tive than con­crete – chiefly be­cause of ce­ment, the bind­ing agent in con­crete.

Ce­ment pro­duc­tion is a big driver of cli­mate change, re­spon­si­ble for 5% of man-made car­bon diox­ide (2008 data from the Ce­ment Sus­tain­abil­ity Ini­tia­tive, a coali­tion of ma­jor ce­ment com­pa­nies world­wide). Pro­duc­tion of ce­ment ex­ceeds 2.6 bil­lion tonnes a year and is grow­ing at 5% an­nu­ally – this gives for a lot of car­bon load.

For ev­ery tonne of ce­ment pro­duced, about 0.8 tonne of car­bon diox­ide (CO2) is re­leased, the bulk of it when lime­stone is heated at high tem­per­a­tures. The com­bus­tion fuel, mostly coal, emits CO2 as does lime­stone it­self, which is cal­cium car­bon­ate (CaCO3). The min­ing of lime­stone also de­pletes our nat­u­ral re­sources, dis­fig­ures the land­scape, and causes noise and dust pol­lu­tion.

“Ce­ment man­u­fac­tur­ing is fun­da­men­tally an un­sus­tain­able and non-re­new­able process,” says Matthias Gel­ber, co-founder of Maleki, a Ger­man build­ing ma­te­ri­als de­vel­op­ment com­pany. “When we burn lime­stone, we re­lease the car­bon cap­tured in lime­stone by Mother Na­ture over mil­lions of years. Lime­stones are car­bon sinks that we’re de­stroy­ing to make ce­ment. It’s crazy from an en­vi­ron­men­tal view­point.”

To green ce­ment pro­duc­tion, some pro­duc­ers re­place por­tions of the lime­stone with fly ash (byprod­uct of coal power plant), slag (byprod­uct of steel in­dus­try) and vol­canic ash. Re­cy­cling these waste fur­ther curbs air and land con­tam­i­na­tion as well as help con­serve land cur­rently needed for their dis­posal. Some pro­duc­ers have also switched to al­ter­na­tive fu­els such as palm ker­nel shells and tyres dur­ing the man­u­fac­tur­ing process to re­duce car­bon emis­sions.

Last year, La­farge Malayan Ce­ment in­tro­duced two ce­ment prod­ucts which use fly ash. These have re­ceived the Green La­bel cer­ti­fi­ca­tion by the Sin­ga­pore Environment Coun­cil.

In Ger­many, Maleki pro­cesses ground gran­u­lated blast fur­nace slag and fly ash with its pro­pri­etary tech­nol­ogy to make low-level ce­ment prod­ucts.

“By re­plac­ing ce­ment with the in­dus­trial byprod­ucts, we won’t have to burn lime­stone,” says Gel­ber. He is based in Malaysia but his com­pany does not man­u­fac­ture here as fly ash and slag are avail­able only in lim­ited quan­ti­ties and at in­flated prices.

“You can re­duce the car­bon foot­print of con­crete to a low level by us­ing a min­i­mal amount of ce­ment and ac­cel­er­ate the hard­en­ing process with al­ka­line ac­ti­va­tion. There are al­ready ce­ment-free con­crete in the mar­ket. The idea of green ce­ment is us­ing waste ma­te­ri­als that have prop­er­ties sim­i­lar to ce­ment. The Pan­theon in Rome was built from vol­canic ash. In coun­tries such as In­done­sia and China, there is a huge vol­ume of vol­canic ash avail­able that can be used to build build­ings. Some com­pa­nies here are im­port­ing vol­canic ash to make ce­ment. With these tech­nol­ogy, you don’t need ce­ment to make con­crete.

“But the con­struc­tion in­dus­try here is con­ser­va­tive and not keen to change too much as it is al­ready mak­ing money with ex­ist­ing ma­te­ri­als and meth­ods.”

Many gov­ern­ments have man­dated ce­ment pro­duc­ers to use byprod­ucts in their for­mu­la­tions but this is not yet a re­quire­ment in Malaysia. – TanChengLi

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