US Patent 7556319 Apparatus for resurfacing concrete

Concrete on a vertical wall is removed for resurfacing in the substantial absence of microfracturing by a crawler apparatus that is lowered from the top of the wall to the bottom by remote control. The crawler is raised and lowered by cables that are reeled in or out depending upon the direction of rotation of the output shaft of a motor. A rotating nozzle blasts a focused stream of very high-pressure water against the concrete to be removed. The nozzle is carried back and forth along the breadth of the crawler as the crawler descends the face of the concrete wall so that a vertical strip of concrete substantially equal in width to the width of the crawler is removed. The crawler is then returned to the top of the wall and moved laterally to begin removal of the next vertical strip of concrete.