1. Impact of quicklime reactivity and origin on Autoclaved Aerated Concrete productionD. Lesueur (didier.lesueur@lhoist.com), F. Mcke, H. Oeinck, U. Peter, C. Pust and F. Verhelst Lhoist R&D / Rheinkalk / Lhoist

2. Outline Objective Materials Methods Results Conclusions2 3. Outline Objective Materials Methods Results Conclusions3 4. Objective Specifications on quicklime for AAC production are essentially based on reactivity (EN 459-2) 90 80Temperature (C)70 60max min Quicklime50 40 30 20 10 0 01020304050time (min) Is this enough? 4 5. Outline Objective Materials Methods Results Conclusions5 6. Quicklimes with various origin and reactivityCalcination LA1 LA2 LA3 IA1 IA2 IB ICLaboratory Laboratory Laboratory Industrial Industrial Industrial IndustrialLimestone Origin A A A A A B CCaOt60wt.% 95.5 95.6 96.2 93.5 94.0 95.8 93.8min 4.1 5.2 7.6 1.9 3.1 8.2 5.26 7. Quicklimes with various origin and reactivity 80temperature (C)70LA1 4.1min LA2 5.2min LA3 7.6min IA1 1.9min IA2 3.1min IB 8.2min IC 5.2min60 50 40 30 20 051015 time (min)2025307 8. 3 recipes covering P2-0.35, P2 0.4 and P4 0.55 (EN 771-4)Target density Target compressive strength Return Slurry Quartz Sand Cement Lime Anhydrite Aluminium Paste Water/Solid wt. ratioUnits kg/m3 MPa wt.% wt.% wt.% wt.% wt.% wt.% -P2 0.35 300-350 >2 20 50 28 17 5 0.22 0.68P2 0.4 350-400 >2 20 55 25 15 5 0.16 0.65P4 0.55 500-550 >4 20 59 18 19 4 0.08 0.658 9. Outline Objective Materials Methods Results Conclusions9 10. AAC production and monitoring at laboratory scale Mix ingredients Return slurry Hot water (70C) Powders Aluminium paste900 Rpm DissolverMixture30L Bucket Monitor green cake expansion Height and temperature Final hardnessDatalogger Ultrasound sensorThermocoupleGreen cake 10 11. AAC production and monitoring at laboratory scale Autoclaving 225 l autoclave 2 hrs linear increase 6 hrs 11 bars / 190C AAC testing density and compressive strength11 12. Outline Objective Materials Methods Results Conclusions12 13. Quicklimes with same origin and different reactivity Expansion monitoring P2 0.35 1.2height / final height (-)1.1 1.0 0.9LA1 4.1min LA2 5.2min IA1 1.9min IA2 3.1min0.8 0.7 0.6 0.5 0.4 051015202530 35 time (min)404550556013 14. Quicklimes with same origin and different reactivity Expansion monitoring P2 0.35height / final height (-)1.101.051.00 LA1 4.1min LA2 5.2min IA1 1.9min IA2 3.1min0.950.90 101520 time (min)253014 15. Quicklimes with same origin and different reactivity Temperature P2 0.35 75temperature (C)70 65 60LA1 4.1min LA2 5.2min IA1 1.9min IA2 3.1min55 50 45 40 0102030405060708090100110120time (min) 15 16. Quicklimes with same origin and different reactivity Expansion monitoring P2 0.35 1.2height / final height (-)1.1 1.0 0.9LA2 5.2min IA1 1.9min IB 8.2min IC 5.2min0.8 0.7 0.6 0.5 0.4 051015202530354045505560time (min) 16 17. Quicklimes with same origin and different reactivity Expansion monitoring P2 0.35height / final height (-)1.101.051.00LA2 5.2min IA1 1.9min IB 8.2min IC 5.2min0.950.90 1015202530time (min) 17 18. Quicklimes with different origin and reactivity Temperature P2 0.35 75temperature (C)70 65LA2 5.2min IA1 1.9min IB 8.2min IC 5.2min60 55 50 45 40 0102030405060708090100110120time (min) 18 19. Green cake: Summary of findings Thermal monitoring always matches expansion kineticsWith the studied recipes and methods, risk of overheating was observed for P2 0.35 and highly reactive quicklimes (expansion overshoot)With the same limestone origin, the higher the reactivity, the faster the green cake expansion BUT with varying limestone origin, similar reactivities can lead to different expansion kineticsAt the lab scale, green cake hardness essentially not affected by quicklime properties 19 20. Quicklimes with same origin and different reactivity Final AAC propertiescompressive strength (MPa)654 LA IA mean321 250300350400450500550density (kg/m3) 20 21. Quicklimes with same origin and different reactivity Final AAC propertiescompressive strength (MPa)65LA IA IB IC mean4321 250300350400450500550density (kg/m3) 21 22. Final AAC: Summary of findings Final AAC properties were little affected by quicklime originHighly reactive quicklimes (expansion overshoot) gave low compressive strength for the P2-0.35 recipeIB quicklime seem to give consistently higher compressive strength for a given density Tobermorite crystal size?22 23. Outline Objective Materials Methods Results Conclusions 23 24. Conclusions We developped a methodology to study quicklime effect on AAC at the lab scale through Green cake monitoring AAC final propertiesWith the studied recipes and methods, risk of overheating was observed for P2 0.35 and highly reactive quicklimes (expansion overshoot) leading to low compressive strengthWith the same limestone origin, the higher the reactivity, the faster the green cake expansion BUT varying limestone origin, similar reactivities can lead to different expansion kinetics24 25. Thank you for your attention