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Video length: 5 min.
10.4 million houses in France are very vulnerable to cracks. If certain solutions already exist such as the injection of expanding resin or micropiles, which are however heavy and very expensive, the company Cerema is setting up a more sustainable system, presented by Lamine Ighil Ameur, doctor in clay soil mechanics at Cerema .
According the latest census from the Ministry of Ecology, published in June 2021, 10.4 million houses are potentially very vulnerable to cracks. Built on soils exposed moderately or strongly to this phenomenon of shrinkage-swelling, the cracks form with the movement of the clay soil which becomes brittle and shrinks during high temperatures. This phenomenon can occur at any time and any type of construction can be affected by the subject. “What we see today is that there are houses which are very old, which may show signs of drought. There are houses that are 1980s, 1990s, that can have drought cracks. And there are also houses from the 2020s, so new construction.” Lamine Ighil Ameur, a doctor in clay soil mechanics at Cerema, is precisely studying this phenomenon of shrinkage-swelling of clay soils, but is also working on solutions for adapting structures exposed to this phenomenon.
What solutions are possible?
Climate change is accelerating this phenomenon. Since 2015, droughts have become more and more frequent, with an increasing intensity that can be heard over time. Today, there are several solutions to treat the cracks that occur in buildings such as the injection of expanding resin or micropiles but, according to Lamine Ighil Ameur, they are “heavy and expensive”.
Cerema is developing an experimental process called MACH (house comforted by humidification). “The principle consists in recovering rainwater from the roof, storing it in a tank, and then, during the drought period, diffusing this water in a targeted and progressive way around the ground which is just below the foundation footing. It is a very classic drip irrigation system. When the ground is dry, therefore, we have the information, it is captured and then we send it back to the pump system to bring rainwater from the tank and gradually diffuse it around the foundation facades.“This method could thus make it possible to rebalance the moisture content of the soil during the drought period and to avoid having an intense shrinkage phenomenon.