Horizontal Sup-Form Construction-Low Slump Concrete

Low slump (less than 25 mm) concrete when properly proportioned can be used for horizontal slip-form construction of elongated concrete structures 5 ft (1.5 m) or more in height. Elimination of conventional forms saves time, labor, and material costs thereby making this construction method relatively economical. A limitation of the method has been the lack of information on the mechanical behavior of low slump concrete in its fresh state. The mortar-voids mix design method provided an effective means for control of test variables including the water-cement ratio, cement content, and mortar content. Other variables included temperature, air content, and particle shape. Using 6-in. x 12-in. (152-mm x 305-mm) cylindrical samples of fresh concrete, the unconfined compression test was used for evaluation of the yield stress, ultimate strength and elastic and plastic moduli. Experimental data are summarized showing these mechanical properties plotted versus the test variables.