On organically derived SCM. Prof. Per Fidjestol Elkem

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1 On organically derived SCM Prof. Per Fidjestol Elkem

2 Outline There is great need for and interest in SCM s New SCM s, based on burning of organics are being researched in many locations. Examples are: Ash from Rice Husks Ash from bagasse Ash from municipal waste Can other organic materials be used? Wood pellets Biofuel Organic waste in general At a binder consumption globally approaching 4 mio tons, will we need the newer SCM s too? Can you possibly hope to partly replace FA and slag? 2

3 Main drivers for SCM s in binder systems Reduce clinker content of binder For CO 2 For lack of raw materials for cement production Durability/service life SCM s mainly have shown very benefial properties in terms of, especially chloride resistance, but also ASR, sulfate etc Albeit often at a much more advanced age than 28 days 3

4 Ash from organic sources Possible source matarials High SiO 2 content organics; Some examples (but numbers must definitely be checked) Rice husks: 20-25% (about 600 million tons of rice); 25 million tons of RHA Pine: 5% Larch: 7% Spruce: 12% Bark 26% Wood chips 26% Wood shavings 25% Winter wheat stalks 54% (ab. 600 million tons of wheat gives 5 billion tons of stalks etc Combustion process that minimizes carbon residue and prevents crystalline silica 4

5 Silicification in and by cells has been common in the biological world for well over a billion years. In the modern world it occurs in bacteria, single-celled organisms, plants, and animals (invertebrates and vertebrates). Prominent examples include: 5

6 Plant Components of Interest Alkali metals, in combination with silica and sulfur, are primarily responsible for melting or sintering at relatively low temperatures. This undesirable process is facilitated by the presence of chlorine. The typical range in concentration (on a dry matter basis) of these critical components in grasses are as follows: Silica (1-4%) Alkali metals ( %) Chlorine ( %) Sulfur ( %) 6

7 Our experiences RHA Bagasse More to come at UiA 7

8 Main challenges Raw materials availability and quality Burning process Post treatment of ash Distribution And, of course, How to make this commercially viable? Marketing Sales Cement Companies? 8

9 Our experiences, RHA Elkem has performed testing on RHA in order to seek a supplement to silica fume Results: Milling necessary, for even burning and efficient product Performance in lab highly dependent on PSD 9

10 Top 20 Rice Producers by Country 2010 (million metric ton) [51] People's Republic of China India Indonesia 66.4 Bangladesh 49.3 Vietnam 39.9 Burma 33.2 Thailand 31.5 Philippines 15.7 Brazil 11.3 United States 11.0 Japan 10.6 Cambodia 8.2 Pakistan 7.2 South Korea 6.1 Madagascar 4.7 Egypt 4.3 Sri Lanka 4.3 Nepal 4.0 Nigeria 3.2 Laos 3.0 Source: Food and Agriculture Organization 10

11 RHA testing for concrete

12 RHA 12

13 PSD Risaske etter Prim agg metode Rice Husk USA, Primary agg method Rice Husk Ash India PA-method Rice Husk Thai, Primær EM 920D % Størrelse, micron

14 MPa % PC 5% MS 10% MS 20% MS 5% RHA 10% RHA 20% RHA 15% RHA + 5% Silika

15 Klorid ion gjennomtrengning Kontrollblanding % Silika % Silika Coulomb % Silika 5% RHA % RHA % RHA %RHA+5%Silika dager

16 Chloride Profiles RHA REF 10% MS 10% RHA 20% RHA ppm Cl mm

17 Transport coefficient Transport coefficient 1.4E E E-11 m 2 /s 8.0E E E E E+00 REF 10% MS 10% RHA 20% RHA Addition

18 Mix ID Average Adjusted Charge, Coulombs Penetrability of Chloride Ions Mix >4000 Mix <3599<4000 Mix <472<1000 Mix <429<1000 Mix <833<1000 Mix <859<1000 Mix <487<1000 Mix <494<1000

19 Bagasse The annual world production of sugarcane is 1.6 billion tons, and it generates 279 million metric tons (MMT) of biomass residues (bagasse and leaves). 19

20 Bagasse World sugar production (1000 metric tons) Country 2007/ / / / /12 Total 163, , , , ,247 Other 38,424 37,913 37,701 37,264 39,474 Brazil 31,600 31,850 36,400 38,350 35,750 India 28,630 15,950 20,637 26,650 28,300 European Union 15,614 14,014 16,687 15,090 16,740 China 15,898 13,317 11,429 11,199 11,840 Thailand 7,820 7,200 6,930 9,663 10,170 United States 7,396 6,833 7,224 7,110 7,153 Mexico 5,852 5,260 5,115 5,495 5,650 Russia 3,200 3,481 3,444 2,996 4,800 Pakistan 4,163 3,512 3,420 3,920 4,220 Australia 4,939 4,814 4,700 3,700 4,150 20

21 Our experiences, Bagasse For each 10 tonnes of sugarcane crushed, a sugar factory produces nearly 3 tonnes of wet bagasse. moisture content of bagasse, typically 40 to 50%, A typical chemical analysis of bagasse might be (on a washed and dried basis): Cellulose 45 55% Hemicellulose 20 25% Lignin 18 24% Ash 1 4% Waxes <1% 21

22 Bagasse Bagasse Leaves 22

23 Bagasse in the lab Finely ground, great material Works as RHA As with RHA, production process, including temperature, important 23

24 Some thoughts about the future How long will sufficient fly ash be available in some (western) economies? Germany Denmark US Slag? Can these be replaced? 24

25 Can these be replaced by? Silica fume NO (Theoretical < 2 Mtons) RHA NO (Theoretical 25, realistic max5 million tons) Bagasse NO (Theoretical million tons) Perlite fines or even milled perlite not really. Reserves 7 billion tons Zeolite no Other ash? Maize 1.5 bio tons Wheat- 9 bio tons??? What Difficult to compete with Silicon and Limestore based cement And amorphous silica is a very valuable fertilizer 25

26 But are organic ashes sustainable at all? Plants extract e.g. silicon from the ground Burning or plowing under returns these elements to the ground Extracting for use in concrete means that you eventually (critically?) deplete the SiO2 content of the soil CONCLUSION : RHA, Bagasse and other organic ashes are not sustainable! 26

27 An attempt at conclusion If or when traditional large volume SCM s are not available Reduce the amount of cement clinker needed by: Seeking to make Only high strength cements FOCUS on service life of concrete structures Recirculate concrete and components more prefab Build flexible Re-train designers out of the MPa trap Teach them also to avoid restrictions on SCM s, apart from relevant performance criteria 27