Modern technology formwork business has moved far from the existing practice for decades. From the point of view of technological operations of solid concrete construction in a formwork principle has changed a bit. But the changed requirements to the quality of the molded using the formwork, concrete forms.
From the history
The formwork system used in Ancient Egypt – so says French architect Berto. To make such conclusion, he has helped multiple studies of Egyptian pyramids, including the famous pyramid of Cheops. According to Berto, two and a half thousand years ago the ancient Egyptians knew how to make artificial rocks — some kind of cement block. They resorted to the method of the formwork. That is, in the form of thin metal sheets poured mortar made of sand, stone chips and water from the Nile. Artificial solution of the Egyptian builders had filled the seams between the blocks. Thus achieved the effect of a single monolith, discouraging many centuries scientists around the world.
A scientific guess of the scientists architect is not just considered unlucky the author was accused of blatant fiction. But Berto won’t budge. In his conjectures of a French architect is guided by the fact that they studied the stone blocks so tightly fitted to each other that between them does not pass even a sheet of paper. In II-III Millennium BC to achieve this by a simple sanding was virtually impossible. Etogonuzhno was to cut the stone raw, like a thin string, cut the cheese. Time, the sun and the dry climate has left its mark on the mysterious structures, so the precise answer to the question of the origin of one of the wonders of the world did not dare to give one.
The manufacture of modular formwork in Ukraine is not more than two or three years, although domestic production every year ousting imported. According to the operators, last year the Ukrainian formwork systems provide 10-15% of total sales of the formwork.
The increasing demand for formwork system is primarily due to the increase in the volume of housing construction with the use of monolithic frame method. Today this method is considered to be one of the most convenient and less costly in construction. It should be noted that the demand for formwork systems in the past year increased not only in the capital but in other regions — Dnepropetrovsk, Zaporozhye, Kharkiv and Western Ukraine.
THE THEORY OF FORMWORK SYSTEMS
Formwork (deck encase to provide a flooring of boards, etc.) is a collection of elements and details intended for giving a desired shape of the monolithic concrete or reinforced concrete structures, erected on the construction site. The choice of formwork depends on the nature of cast structures or facilities, the ratio of their geometric dimensions, the adopted production technology of works, climatic conditions. In the more traditional version of the formwork is identified with the corresponding wooden form. This version of the definition used confirm the formwork still many construction sites construction, cobbled together from boards, which is the waste of the lumber industry.
The function of formwork systems is to serve as a temporary form for concrete mix, thanks to which she acquires after attaining a certain strength of concrete, incorporated in the project quality appearance. And the question of the extent to which individual formwork systems cope with this problem, is for a modern building principal. Quality requirements made with the help of formwork systems in concrete structures induce technical progress, which in this case is called induced. But for typical formwork systems and Autonomous technical progress, as changes in some of their elements necessitate changes in other parts of the system.
In the case of induced technological progress dominant issue are the features of concrete. In the application of concrete over the past two decades has undergone substantial changes. The most characteristic, according to experts, are the following trends: growing need for winter concreting and qualitative changes in the composition of concrete mixtures related to the wider use of chemical additives for concrete. This phenomenon leads, in turn, the importance of maintaining in the process of laying concrete water-cement ratio. For this reason, any uncontrolled water evaporation from the concrete mass or leakage is unacceptable.
Another trend, which significantly determines the demands made by the construction of formwork system, is the gradual shortening of the concrete gains Stripping strength. As a result radically changed the relationship between time of installation of formwork and the time of solidification of concrete. Currently the concrete can reach Stripping strength within a day or two to three days. In other words, turnover formwork systems largely depends on the time of its Assembly and disassembly, and requirements for concrete quality have no relationship. This is a standalone issue of improving formwork system, the solution of which affects the economic efficiency of application of one system or another.
PRACTICE FORMWORK SYSTEMS
Another factor to take into account when considering the formwork systems is their specialty. For each of the technological types of monolithic concrete construction and for specific tasks are developed a special formwork system.
Collapsible climbing formwork malashicheva
Currently, this formwork system is most used in construction. It consists of separate panels, locks for their Connections, and supporting elements, perceiving the load, and fixtures. Some systems can be pre-pre-Assembly of panels in the panel or spatial units and their subsequent mechanized Assembly and disassembly, which dramatically increases productivity. From the elements collapsible-re-fixed formwork is possible to collect virtually any form for concrete structures foundations, walls (height 10-15 m), floors. Upon reaching the concrete strength that allows Stripping of formwork, the formwork is disassembled and relocated to a new location.