Page 30

2014SprShotcreteEMag

Pool & Recreational Shotcrete Corner Grade 60 (Grade 420) steel. We reinforced and shot just as we would with any other vessel. In this area, where we see 100°F (38°C) temperature differentials, controlling the effects from freeze/thaw exposure is always important. This vessel, which is 3 ft (1 m) thick on the bottom, sits atop an 18 in. (0.5 m) layer of gravel with a drainpipe so that we’re constantly dewatering the area beneath the feature. Com- bined, that takes us down to a depth of 4.5 ft (1.5 m) right at the deepest freeze level, meaning water will never gather and freeze around the outside of the structure. The granite material gives the piece its period- appropriate quality. Both the feed trough and the granite slabs in the runnel were all quarried and used originally more than 100 years ago. The surfaces are rough and weathered, creating the illusion that the feature has been there for hun- dreds of years. The slabs are set in a plastic, non-set layer of grout. George didn’t want to see any concrete, but we convinced him to give us 1/2 in. (13 mm) between the slabs where we could install recessed grouting. The grout, a concrete mortar mix, enabled us to level the stones, which vary in thick- ness, as well as control any potential movement. As is, the slabs appear to abut each other with no visible concrete (Fig. 3). In preparing the stone, we had to remove chunks of old mortar and other material that remained in some of the rougher spots. The pieces in the floor of the runnel varied from 6 to 12 in. (150 to 300 mm) and had to be cut to Fig. 3: Shotcrete trough with reclaimed granite installed. Notice the a uniform dimension so we could create a level shotcrete step support for granite stones surface for the water to flow over. We had to be very careful not to split any of the stones— meaning that we had to be extremely careful when saw-cutting the large pieces while much of the fine work was done with hand tooling. It took quite a long time, but we ended up being able to use all the pieces George had selected for the feature. The stones were carefully placed with an articulating excavator, which we had to counter balance with extra weight on one side so it wouldn’t tip over while moving the slabs. The mortar bed enabled us to level the stones on either side of the runnel, making up for as much as 6 in. (150 mm) variations in thickness. The water is not recycled, meaning it’s not filtered or chemically treated, but instead flows from a natural spring on the property through the feed trough, then down the runnel, which spills Fig. 4: Feed trough with runnel, view to the south into a drain concealed below the pea stone and 28 Shotcrete • Spring 2014


2014SprShotcreteEMag
To see the actual publication please follow the link above