Method for applying a fiber-containing building material, especially by means of 3D printing, comprising the steps of - providing a hydrous mineral binder composition, at least one aqueous accelerator and fibers, - feeding the hydrous mineral binder composition, especially by means of a pump, to a continuous mixer comprising • a drive, • a mixing region comprising at least one inlet and at least one dynamic mixing element, where the dynamic mixing element comprises a stirring shaft having stirring elements, the stirring elements taking the form of pegs, and a distance between adjacent stirring elements being at least 60%, more preferably at least 80%, of the length of the longest fibers and • a conveying region connected to the mixing region and comprising at least one conveying device and an outlet, the hydrous mineral binder composition being conveyed through the at least one inlet into the mixing region, - feeding the fibers into the mixing region of the continuous mixer, - feeding the at least one aqueous accelerator for the setting of the hydrous mineral binder composition into the mixing region of the continuous mixer, - mixing the at least one aqueous accelerator with the hydrous mineral binder composition and the fibers in the mixing region of the continuous mixer to give an accelerated fiber-containing mineral binder composition, - conveying the accelerated fiber-containing mineral binder composition by means of the conveying device to the outlet, and - applying the accelerated fiber-containing mineral binder composition, in particular layer by layer by way of a movable printing head. - providing a hydrous mineral binder composition, at least one aqueous accelerator and fibers, - feeding the hydrous mineral binder composition, especially by means of a pump, to a continuous mixer comprising • a drive, • a mixing region comprising at least one inlet and at least one dynamic mixing element, where the dynamic mixing element comprises a stirring shaft having stirring elements, the stirring elements taking the form of pegs, and a distance between adjacent stirring elements being at least 60%, more preferably at least 80%, of the length of the longest fibers and • a conveying region connected to the mixing region and comprising at least one conveying device and an outlet, the hydrous mineral binder composition being conveyed through the at least one inlet into the mixing region, • a drive, • a mixing region comprising at least one inlet and at least one dynamic mixing element, where the dynamic mixing element comprises a stirring shaft having stirring elements, the stirring elements taking the form of pegs, and a distance between adjacent stirring elements being at least 60%, more preferably at least 80%, of the length of the longest fibers and • a conveying region connected to the mixing region and comprising at least one conveying device and an outlet, - feeding the fibers into the mixing region of the continuous mixer, - feeding the at least one aqueous accelerator for the setting of the hydrous mineral binder composition into the mixing region of the continuous mixer, - mixing the at least one aqueous accelerator with the hydrous mineral binder composition and the fibers in the mixing region of the continuous mixer to give an accelerated fiber-containing mineral binder composition, - conveying the accelerated fiber-containing mineral binder composition by means of the conveying device to the outlet, and - applying the accelerated fiber-containing mineral binder composition, in particular layer by layer by way of a movable printing head.