Fabrication and characterization of self-ignition coal gangue autoclaved aerated concrete

• Ca/Si ratio should be firstly considered when preparing self-ignition coal gangue autoclaved aerated concrete.
• W/S ratio and the slurry expansion both significantly affect the microstructure and the mechanical behavior.
• Higher Ca/Si ratio is conducive to form towards the tobermorite.

By conducting the orthogonal design for the best mechanical properties of the matrix parts without introducing air pores in advance, the self-ignition coal gangue: lime: cement: gypsum = 54: 23: 20: 3 accompany with 1.3‰ aluminum powder is determined as the optimal mix proportion of the self-ignition coal gangue aerated concrete. Meanwhile, the reasonable Ca/Si ratio of the elements is found to be 0.82. XRD results show that the hydration products of self-ignition coal gangue autoclaved aerated concrete (SCGAAC) are mainly consisted by CSH gel and tobermorite phase, moreover, SEM approved that a higher Ca/Si ratio is conducive to form the tobermorite phase under the autoclaved conditions. The induced pores in SCGAAC are mainly interconnected open cell structure with middle characteristic latitudinal dimension between 0.5 and 2 mm.

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