A method for the production of exposed aggregate concrete slabs out of the method and device for

摘要

A spray device (1) (Fig. 1) serves for spraying the face of washed concrete slab blanks (3a) which, coming from a slab press, are set down upright at a transport track (11) by means of a setting-down mechanism. The spray device (1) has a vertically movable spray head (14), which sprays a slab which has just been set down from bottom to top with a setting retarder. For the next setting-down movement of the following slab, the spray head (14) is moved into a position of rest above the plane of the slabs. It is of essential importance that the setting retarder only gets onto the face to be sprayed of the slab blank (3a) and that surrounding areas are screened off from the spray jet. This is essentially carried out by arranging a collecting pan (15) below the spray head (14). To confine the underside of the spray, the said pan has a confining edge (16), which is set back from the front edge (17) of the collecting pan, in order that material diverted at it cannot get beyond the area of the collecting pan (15). Spray jet confining means may also be provided at the sides. This also has the effect in particular of preventing setting retarder from getting onto the receiving surface of the transport track (11) and thereby getting onto the bearing ends of the blanks (3, 3a), where otherwise underwashing effects would occur later in an undesirable way. The spray device (1) is integrated into the working area of the setting-down mechanism, this setting-down mechanism and spray device working in an alternating cycle. As a result, no additional station or the like is necessary for the spray device. The timing of the working cycle of the setting-down mechanism is also utilised, in particular the idle time as far as the set-down slabs are concerned which exists when a slab is being picked up at the press is utilised for spraying the said slabs. IMAGE