Page 33 - Demo

AAC WORLDWIDE %u2022 2.2026 SCIENCE & INNOVATION 31These mortars are prepared from 40-70 M-% AAC granulate, 30-60 M-% calcium sulfate binder and additives. The surface of these products is defined by the mould and there are fewer restrictions on the maximum particle size of the AAC granulate. However, with increasing granulate size the mortar is less likely to fill out corners and the granulate tends to float. The effect on the product%u2019s density is determined by the volume controlled by the bulk density of the AAC granulate. By the use of 60 M-% AAC granulate with a bulk density of ca 500 kg/m%u00b3 the dry density of the product can be reduced to 700 kg/m%u00b3 while the compressive strength is approx. 3 N/mm%u00b2 and the flexural strength is 1 N/mm%u00b2 according to EN 13279-2:2014 [10].Conclusion and summaryAAC powder < 1 mm maximum particle size is suitable for lightweight gypsum based building plaster whereas AAC granulate > 1 mm maximum particle size can be used for gypsum-based self-levelling AAC unit crystallite matrix AAC powder <1 mmbulk density age compressive strengthair porositybulk densityskeletal densitybulk density (loose)bulk density (grain)packing efficiencymean particle size d50kg/m%u00b3 a N/mm%u00b2 Vol.-% kg/m%u00b3 kg/m%u00b3 kg/m%u00b3 kg/m%u00b3 % mm390 25-35 ~4.9 61 1000 2290 570 980 57 0.174590 25-35 ~4.2 43 1030 2450 560 960 58 0.134300 1-3 ~2.2 65 850 2270 490 830 59 0.269670 35-55 ~2.9 42 1150 2430 630 1070 60 0.147450%u2013580 - - - - - 670 1090 61 0.156340%u2013570 - - - - - 710 1130 63 0.162bulk density (loose) bulk density (grain) packing efficiency max. particle size mean particle size d50kg/m%u00b3 kg/m%u00b3 % mm mm480 - - 20 2.2500 910 55 4 0.5660 1190 55 4 0.7Fig. 3: Scanning electron microscopy image of gypsum crystallites (ca 10 %u00b5m, on the right) with AAC particles and tobermorite-crystallites (ca 1%u00b5m, in the upper left corner).Table 1: AAC powder < 1 mm for lightweight gypsum based building plaster obtained by a screen ball millTable 2: AAC granulate for self-levelling mixtures; < 4 mm obtained by a jaw crusher or < 20 mm obtained by a single-shaft shredder10 %u00b5m