Abstract: A formwork for manufacturing a concrete structure which is composed of one or several folding portions, provided with one or several hollow portions which in an unfolded and stretched condition have the shape of the contours of portions of the concrete structure to be formed, whereby the formwork can be placed on a bottom in an initial condition and whereby, by pouring or pumping concrete slurry in the hollow portions of the formwork, the formwork can be taken from the initial condition to the stretched condition so as to form the respective portions of the concrete structure.