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Bags of quality for composting

Q What is your product?

BioSac by Calcia, developed by Ciments Calcia, Mondi Packaging, Groupe Barbier and LCI, is a biodegradable cement bag.

Q How does it work?

BioSac uses a three-layer sacking technology made by combining a free film made from the compostable bioplastic biolice with two Kraft paper layers.

By utilising biolice, which is a compostable bioplastic made from maize flour, LCI removed the polyethylene layer traditionally used in cement sacks.

The new bag offers the same resistance and conservation qualities while bringing positive environmental benefits.

Q Where would it ideally be used?

In the waste management of construction sites.

Q How did you create the product?

We wanted to find out whether used biodegradable cement bags could be of value to the composting industry.

For a trial, we made two windrows: the control windrow was made up of 50 tonnes of organic waste while the trial windrow was made up of 48 tonnes of organic waste and 2.5 tonnes of used cement bags.

The trials began with a three-month fermentation phase, with eight reversals for homogenisation and five waterings for launching waste fermentation and enabling a temperature rise.

After this, a maturation phase started, followed by a screening step with mechanical separation of the final compost from elements with a diameter higher than 40mm.

At the end of the experiments, the trial windrow containing cement bags presented similar evolution to the control windrow. Only 100kg of paper from the bags was found in the screenings of the initial 2.5 tonnes of used cement bags added. There was no trace of cement or biolice film, and the mass balance was identical for the two windrows - so the compost quantity was equal.

Q What are the benefits?

Our trial showed that the incorporation of used BioSac bags into composting has no effect on compost quality.

There was no difference in physical characteristics, pathogenic micro-organisms were totally destroyed during the fermentation phase, and the organic and metallic traces in the compost obtained from the trial windrow fulfils the NFU 44051 norm, allowing the use of the compost for soil fertilisation.

So BioSac by Calcia cement bags can be collected and used as raw material in every composting facility.

Answers supplied by LCI. For details visit:

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