The invention relates to a method for improving the strength of a porous or permeable material. The invention particularly relates to a method comprising: contacting at least one type of calcification bacteria with a porous or permeable material; contacting the calcification bacteria with a calcification medium; said method or process further comprising: contact the calcification bacteria with an adhesion agent and the assimilation of the adhesion agent by the calcification bacteria. The invention can be used for reinforcing floors, in particular liquefiable floors, for the stabilization of slopes, for the calcification of non organic or organic substrates, and for the restoration or protection of a frontage.