Static structures (e.g. – buildings) – Facers; e.g. – modules – mutually bonded by internal settable...
Patent
1997-05-08
1998-09-15
Kent, Christopher
Static structures (e.g., buildings)
Facers; e.g., modules, mutually bonded by internal settable...
524051, 524053, 5274214, 527815, 527931, E04B 214, E04B 200
Patent
active
058062645
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD TO WHICH THE INVENTION RELATES
The present invention relates to a new type of prefabricated concrete walling that is structurally adjustable to suit many applications and to a method of making same.
The degree of structural flexibility allows this semi walling system to be commercially viable in all types of construction in non, semi and full load bearing applications.
BACKGROUND OF THE INVENTION
Prefabrication of walling is well understood, the most common being made from reinforced concrete in the form of transportable panels. However in actual practice these types of walling systems although speeding up construction have failed to revolutionise the industry and in most cases have been proved to be more expensive than conventional construction, particularly in developing countries.
The main reason for this failure is that these prefabricated systems were designed in developed countries to save on labour skills and labour costs, whereas in developing countries materials costs account for the major portion (up to 80%) of the cost breakdown between materials and labour, which is the reverse of developed countries where labour accounts for the major portion (up to 75%). None of the immense number of building systems so far devised and tried in developing countries has saved enough in materials costs to be effective in those environments and markets which are traditionally masonry oriented. Residential construction in developing countries is almost all masonry type construction, very lightweight plasterboard systems have failed to satisfy consumer requirements.
The relatively high cost of concrete systems is associated with the use and quantity required of Portland cement to make construction quality concrete. Portland cement accounts for approximately 75% of the total cost of structural concrete and therefore any reasonable cost reductions to be made in concrete costs must be associated with a significant reduction in cement content.
Portland cement is also a very slow hardening binder, preventing rapid reuse of expensive moulding and other production equipment. Various methods have been devised to speed up the hardening process such as, steam curing, hot water mixing, intense vibration, low water/cement ratios, accelerators, accompanied always with a higher cement content than would normally be required if the concrete were cast in situ on the construction site with several weeks in time to achieve structural maturity.
Unfortunately all of these measures to gain sufficient early strength add significant cost onto prefabricated products either directly or indirectly through higher capital costs or higher material costs, and yet, the most economical method will only yield product every 24 hours and with very high cement contents every 12 hours.
Unless a manufacturing cycle of 12 hours or less can be achieved the benefits of prefabrication are largely negated as factories become disproportionably large and costly, in addition, the production of product is too slow to fulfill the real potential of prefabrication techniques. Most reinforced concrete structures are designed to achieve adequate strength in 28 days and reducing this time down to a matter of hours is costly.
These higher capital costs are associated with long cycle times ie, equipment reuse and factory space become critical because prefabricated concrete products have to be strong enough within 12 hours to withstand the stresses of de-moulding and handling. In order to achieve this cycle time criteria the product is manufactured to a much higher degree of strength than is required for it's use as a normal structural element in a building.
These factors are further exacerbated by the weight of the prefabricated product being produced create more stress around the lifting zones during de-moulding. The lighter the product, the less stress and the less cement hydration (hardening) is required.
Although there are some cases where the extra costs of the prefabricated systems are justified such as rapid multi storey construction or unav
REFERENCES:
patent: 1021780 (1912-04-01), Johnson
patent: 2825221 (1958-03-01), Brouk
patent: 4031682 (1977-06-01), Renkert
patent: 4164831 (1979-08-01), Messick et al.
patent: 4315391 (1982-02-01), Piazza
patent: 4323080 (1982-04-01), Mullins
patent: 4548007 (1985-10-01), Newman
Kent Christopher
Phillip Boot Holdings Pty Ltd
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