December_1966 — Page 68

Setting up slipform forms to slio bins

tion has been constructed the wheat conditioning bins, of which there are 19. each measuring 9 ft. by 9 ft. by 91 ft. high.

The mill section of the building length 172 ft.. height 150 ft., width 30 ft. of 10 storeys, houses two complete sets of pneumatic milling equipment and is backed by a five- storey warehouse length 185 ft.. width 38 ft., and height 80 ft. for storing bagged wheat flour.

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Two outlet tunnels, 6 ft. 6 in. by 5 ft. 0 in.. are constructed under- ground from the mill building, lead- ing to the waters edge, allowing bagged flour to proceed by gravity from the mill for loading in coastal vessels. Also. in this section. 12 Nos. 9 ft. by 9 ft. by 60 ft. high surge bins have been constructed for the storage of wheat flour.

The administration and laboratory areas are fully air conditioned and three separate lifts serve the various sections of the building.

All rendered walls were given a coating of cement wash to maintain a conformity with the concrete walls of the silos.

Slipforming

and

To accelerate construction work, it was decided to slipform the silo block. the conditioning bins surge bins, using the Swedish method of slipform casting developed by AB Byggforbattring. Stockholm.

March 1965. First stage of Silo bins com- plete with shuttering of first floor of mill building in hand

This was the first time this method of construction had been used for any structure in Malaysia. The charac- teristic feature of the method of slip- form is the uniform simultaneous raising of the forms at all points con- tinuously by a number of hydraulic

jacks connected to yokes which climb steel jack rods incorporated in the overall wall reinforcement. The hy- draulic jacks are connected to a hy- draulic pump centrally located which can be operated by one man,

As the forms rise and the jackrods become buried in the concrete place- ment, additional rod lengths threaded on, to eventually become part of the reinforcement.

are

The rate of rise of the formwork was governed by the concreting cap- acity, but an average rate of rise of 12 to 15 in. per hour was aimed at. giving concrete three to four hours old as it emerged from the forms. This concrete hardness was found to be the most suitable for sponging down the exposed surfaces to a smooth finish.

This technique, new to Malaysia, has many advantages for the contrac- tor, as well as benefits to the clients. The speed and continuity of the structural system contribute to sub- stantial savings in time and labour. The finish of the bins apart from sponging down was as from the forms.

For this project, the slipform work was designed to be carried out in four stages:

1st stage: 10 circular bins and

2nd stage:

41⁄2 star bins.

8 circular bins and 4 star bins,

3rd stage:

19 conditioning bins. 4th stage: 12 surge bins.

The silo block was slipformed in a period of 15 working days and the whole of the building took 15 work- ing months to complete.

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Far East Architect & Builder December, 1966