Marnell Masonry thought the Excalibur Hotel in Las Vegas was a good bet. Marnell, a Las Vegas masonry contractor, started building the four 28-story towers of the 4,000 room hotel in January 1989. Because of cast-in-place concrete corridor shear walls, it took 6 days to construct each of the first 13 floors. Since then, it's taken only 5 days to complete a floor, even though the masonry corridor shear walls added 2,500 extra block to each floor. FAST WORK This fast construction rate--a floor a week per tower--was achieved by careful planning and repetition. Each tower is being treated as a separate building, each with its own foreman, crews, and equipment. Work is done in five steps: STEP 1: Crew 1 lifts materials onto the floor, distributes them, then marks the locations of walls. STEP 2: Crew 2 builds the masonry walls up to the 4-foot height. STEP 3: Crew 3 erects scaffolding and builds the next 4 feet of wall. STEP 4: After the walls for a floor level are completed, the general contractor lifts room-size, site-cast concrete slabs and sets them on the walls. Shoring is placed under each concrete slab to support the slabs and superimposed dead loads. STEP 5: Standing on the floor slabs, Crew 4 threads wall reinforcing down into the block cores. Then workers grout the exterior masonry curtain walls and interior masonry shear walls. MEETING MORTAR NEEDS Marnell Masonry decided to use two-compartment silo mixers that deliver up to 4 cubic yards of mortar per hour. Two such silos were set on the top floor of each tower. REINFORCEMENT Because the hotel is in a Zone 2 seismic area, the masonry walls had to be heavily reinforced. At the bottom floors, #10 and #11 rebars were placed vertically in block cores and grouted. As floor levels get higher (and loads get lighter), smaller vertical rebars are used.