Concrete engineer, Cooby Creek Satellite tracking Station and Cato Island – Never a dull moment with Com Works
There was a lot of work in progress at Amberley as well as in Townsville where the army were expanding and Lavarack Barracks needed extra accommodation, ancillary facilities and store buildings with associated road works etc., With all the work in progress I was nominated the region’s Concrete Engineer as a part-time assignment. The Department had their laboratory at Nott Street, South Brisbane and this is where tests for gravel and concrete aggregate were done. Before a contract commenced representative samples were forwarded for testing to ensure they complied with the specification and check the mix design. Portland cement was not a problem as there were only a couple of cement works in Queensland and their products were known to comply with our standards, whereas in Papua New Guinea cement was shipped from practically every country in the world and care had to be exercised.
About this time pozzolan or fly ash was introduced for general use rather than for specific uses and was used as a cement replacer, but this was not permitted in our contracts as such. The laboratory tested road or pavement base gravels for grading, clay content, linear shrinkage etc., but this was done for the Civil or Construction Section direct. Concrete mix design was to ensure the specified strength was obtained so it nominated the water/cement ration, quantity of added water, weight of cement and quantity of each specific aggregate. Batching was usually by weight and water was total free water and had to be adjusted for wet aggregates. With aggregates the specific gravity was calculated and grading curves plotted for the aggregate sizes – plotting size against % pouring. The sieve sizes were generally 1 ½”, ¾”, 3/8”, 3’16”, to No. 100. The results were combined graphically to approximate the specified grading. It was usual for three sizes of crushed aggregate to be used: ¾, 3/8, 3/16, but occasionally a fine sand was needed. Often a trial batch was made and tested and in large jobs a trial run made. Test Cylinders were taken for 3 day, 7 day or 28 day tests; the three day or seven day test giving a result which can be correlated with the twenty-eight day strength and so give a warning if something was amiss. This happened when a runway pavement was being poured and the three day test indicated something was wrong resulting in finding that the air entrainment mixer was faulty and it is particularly useful for columns in large multi storey buildings.
Another interesting job came my way in the ATS Cooby Creek Satellite Tracking Station outside of Toowoomba. The electronic equipment was in vans or trans-portables and needed to be connected to the disc antenna by cable ducts and walkways. That was simply a layout plan but the antenna had to be mounted on a foundation with practically no settlement or movement. The foundation investigation revealed large basalt boulders over the site so the foundation was excavated to rock and the reinforced concrete foundation rock bolted to the boulders using high tensile rock anchors.
Then came Cato Island, automatic weather station. Cato Island was a coral island with high ground above surge level, stunted sea grasses and birds everywhere. The equipment was to be installed in a prefabricated insulated room make up of a polystyrene core sheeted each side with aluminium sheets interlocking. This was anchored to a reinforced concrete floor cast on the ground and surrounded by a portal frame shed sheeted with heavy kliplock sheets with a narrow passageway around the centre building. Vents were provided all sides at the top and bottom for ventilation and these vents designed to let the heat out and keep the water out. An aerial mast was nearby with the anemometer and transmitter aerial connected to the building along with the rain gauge and other instruments just above the ground. I think the building was designed to resist 120 mile per hour winds. This project was built by day labour for the Department.
The lighthouse vessel MV Cape Moreton was used to transport labour and materials to the island and the vessels LARC used to get it all ashore. There were two Departments interested in offshore works, the Department of Transport and the Bureau of Meteorology. Transport had a continuing program of servicing the off-shore lights or landfall lights and Meterology were expanding their facilities to have a network of offshore automatic weather stations for cyclone warnings. There were numerous manned lighthouses along the Queensland coast and these often had three families or individuals operating them – the head Lighthouse Keeper and two assistants, each with their own house, so there was a constant need for access for personnel, stores, maintenance and new construction. This need resulted in three special vessels or Cape ships being built for the service of all lighthouses along and off the Australian coast. They were the Cape Moreton, Cape Pillar, and Cape Don. The Moreton serviced Queensland, the Cape Don serviced West Australia and Northern Territory and the Pillar serviced the southern states, but the roster moved them around as the need arose. The three vessels were identical and each had an amphibious vehicle or LARC on davits, could accommodate up to twelve passengers, had a large hold for carrying construction materials or stores and a crane for loading and unloading. Everything needed for construction and living in these remote sites had to be got ashore and the Cape vessels were designed for this. Bagged aggregate for concrete along with fresh water and bagged cement were stowed below deck and a special plastic lined bag was ordered for the cement. What could not be stored in the hold was secured deck cargo such as steel and timber piling, pile driving rigs and prefabricated sections for towers etc., Commonwealth Department of Transport was responsible for the landfall lights. The other light, beacons and navigation aids within the Port areas were the responsibility of the then State Department of Harbours and Marine. The Commonwealth Department of Transport had a depot on the river bank at New Farm where the Cape Moreton berthed when in Brisbane. I was associated with this when a materials store and accommodation building was required. Our architects planned the development, a store and workshop at ground level with two accommodation units above for the needs of families or officers in transit. It involved a monorail suspended from the floor beams above and had to service each side of the store for lifts around two tons requiring a special junction transfer switch.
When doing an inspection of the reinforcement for the suspended floor the steel fixer muttered, “I would like to see the person who put this arrangement together.” I replied, “that’s me and I can see the problem with all the laps and splices in the area around the column, so your point is well taken.”
You can learn a lot from people in the field. The wharf needed attention and I was involved with an inspection and report on its condition; it required a few fender piles and some deck replaced. This was the field I enjoyed working in.
Around this time there were a number of contracts let for the expansion of Lavarack Barracks in Townsville and Enoggera Barracks in Brisbane, consisting of steel framed buildings with many portal frames and I was given the job of inspecting them before transport north. With the large portal frames the details of the column-beam connection or knee joint was critical. The boiler makers had not followed the details and had fabricated several joints incorrectly. The shop foreman did not appreciate my rejection of the joints done as remedial work involved back grinding the weld over the diagonal gusset and rewelding to give a full strength butt weld to overcome the possibility of delamination. He did not want to do anything so I made it clear there were a few to be rectified and the remaining ones to be done to detail otherwise they were not leaving the shop and I would be back each day to check. I did not win any friends in that shop but the work went out correct. I was aware you had to be fair and firm as it is not practical to watch every operation and goodwill goes with co-operation, whereas the adversarial approach leads to confrontation which can be counter- productive. A side issue with these buildings after erection was experiencing a problem with the step treads cracking. These were prestressed concrete treads bolted to steel stringers and some were showing cracks in service. It was then realised that a soldier in boots etc., running down steps, puts an impact load approximately double the design load, hence the treads were working in their limit state with no resulting load factor.