Utilization of waste Autoclaved Aerated Concrete as lighting material in the structure of a green roof

• Reuse of waste AAC with natural soil to create a neutral substrate for green roofs.
• AAC–peat mixture respects the UNI 11235 standard.
• AAC–peat mixture is similar to the mixture with natural stones and natural soil.
• Utilization of granular waste AAC reduces the consumption of natural materials.
• AAC cost, obtained by waste materials, is lower than the natural materials one.

Usually, green roofs are made with natural materials, as lapillus or pumice rock, which have the same porous characteristic of the granular AAC. To verify if this substitution was a good hypothesis, we have carried out chemical and physical analysis on a mixture of 70% of soil and natural peat and 30% of granular AAC. We compared all the results with natural green roof characteristics, finding a good connection between these two groups of values. In fact the pH value of the water extract is of 7.23; the organic matter is less than 4.08; the apparent density is 459.2 kg/m2; the demand for high water retention capacity is completely satisfied by the value of 222.62% of the mass of water absorbed relative to the mass of the dry sample. For this reason, we think that the introduction of granular waste AAC within the structure of a green roof could help to reduce industrial wastes and respects the European ideas of a sustainable future.

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