Page 16 - Minutes of Proceedings of Civil Engineers Vol CXCV 1913-14 Part 1
P. 16
56 wENTwoRTH-SHEILDs oN THE coNsrRUcrIoN ox' [Minutes ol bottom beds. 'Ihis rvrr,s arrarnged in order to bond the blocks into the mass healtirrg, tnd tlso to allow the mass rvork to pass under the 7 tail of the hending blocks as much as possible. After a course of headers and stretchers htd been laid at the back and in front for 4 certain length (generally about 60 feet) the hearting between was built up of mass concrete deposited from boxes in the same way as tlre foundation concrete had been laid, a temporary shutter being placed at the end of each length. In this manner the work was brought up to 4| feet above I.W.O.S.T., the top course of blocks and the mass work bebween them being laid in the dry at low spring- tides. Above this level the wall was built of mass concrete de- posited behind shutters in the usual way. Bachtng.-.lrfter the wall had been built up to quay-level, the soft mud which had aocumulated behind it during construction was carefully removed by a grab, and the selected backing referred to on p.54was deposited. The broken concrete was placed first, and extended from ground-surface to low-water level. The ashes were placed above and behind the broken concrete. The two quay-walls numbered 48 and 49 in Fig. 2, Plate 1, were built in a similar manner to the portion of wall for berth No. 47 here described, and when the three were completed, the space they enclosed was filled with ships'ashes, and with chalk from the railway-courprny's quarry at Micheldever. Block -Yaril.-The block-yard lay between berth No. 46 and the Trafalgar Dock (Fig. 2, Plate 1). At its south end were a pair of l-cubic-yard Messerrt, concrete-mixers, which supplied the blocks and tlso a good doal of the mass work. The mixers were stationary, rnd woro fed with brr,llast and cement by a 10-ton derrick crane, which lifted tll mnterials to the top feeding-platform. The corrcreto when mixed was poured into small tip-wagons which ran on orr elevoted railway over the block-moulds, into which they dischorged. The blocks when set were lifted by a 10-ton trovelling golinth rrnd stacked at the south end of the yard. W'hen required for setting they were placed by the goliath on trollies running on & nmrow-gmlge railway, and were hauled by steam- locomotives on to tho stl,ging at the back of the wall. The same trollies conveyod the tlischa.rging-boxes containing the mass concrete from the stotionuy mixors to tbe wall. Bemarlce on Mo,sa Concrele wnder Water.-Although the mass concreto rrsetl in the hurrting of this wall proved satisfactory, it is proboble thnt if tho w:r,ll hrr,d been built entirely of blocks between dock-bottorn nnrl low-watcl leve,l, a rather better anil cheaper structure rvoukl lulvo boon obkrined. The mass hearting was
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