CO² uptake during COnCrete life CyCle - Bygg uten grenser

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CO² uptake during COnCrete life CyCle - Bygg uten grenser

CO ²CaCO ³CrushedconcreteCO ²CementCO ²uptake duringconcrete life cycleThis brochure is based on results from the CO ² uptake project from the Nordic Innovation Centrewww.nordicinnovation.net


WHERE DOES CO ²COME FROM?– CO ² emission from cement productionaccounts for 4% of the total CO ²emission in Denmark.– The CO ² emitted during cementproduction stems from the calcinationof limestone and the burning of fuels.– The calcination of limestone is a processby which limestone (CaCO ³ ) becomesCaO, liberating CO ² gases.– The calcination of limestone accountsfor more than 50% of the CO ²emissions in a cement plant.CO ²neutralfuelsCalcinationof limestoneFossil fuelsWHAT HAPPENS WHEN CEMENT IS USED?– CO ² present in air reacts with thecalcium in the cement forming calciumcarbonate (CaCO3). This reaction takesplace within the concrete and is calledconcrete carbonation.– Concrete carbonation is a naturalprocess and helps reducing theatmospheric CO ² .


WHAT AFFECTS THE RATE OF CARBONATION?PLACEMENT80STRENGTH60carbonation depth (mm)6040200020indoor concreteourdoor concreteburied concrete40 60 80 100carbonation depth (mm)40200020low strength concretemedium strength concretehigh strength concrete40 60 80 100yearsyearsEXPOSED AREATotal carbonationby ~ 1.100 yearsTotal carbonationby ~ 11 yearsTotal carbonationby ~ 1month100 mm 10 mm 1 mmWHEN DOES CONCRETE CARBONATE?– Concrete carbonates during the servicelife of the structure and after thestructure is demolished and theconcrete is recycled for secondary use.– Recycling of concrete means crushingdemolished concrete and reusing it inroad construction.– The carbonation of concrete increasessignificantly after demolition because ofthe reduction in particle sizes due tocrushing.% carbonated1008060402000after demolitionservice life20 40 60 80 100years