Patent Application
20140306088
Concrete slabs have been manufactured over the past years using a variety of forms and materials. The Romans first used a slab composition composed of quick lime, pozzolana and a kind of pumice which is now known as Roman Concrete and this freed the Romans from the use of brick and stone in building structures. This substance was subjected to change and improvement until we have what is now known as modern concrete which is composed of Portland Cement (a powder) and a variety of aggregates to fill a variety of needs.
One question has always been with us, and that is “how do we increase the tensile strength of the cured concrete?” The present answer is the use of specially made steel rods (rebars) embedded in the concrete as it cured and this gives the necessary tensile strength to the cured concrete. It is known to use other materials such as fibres, steel shavings and materials such as horse hair which when added to the concrete mix improve its tensile strength.
Now that a satisfactory additive material has been found, what sort of a container (form) can be used hold the curing mixture as it sets? The form used by early practitioners and still is in use to day is wood. Here the pieces of wood are somehow joined to-gether at their ends to form an outer boundary which is supported by a system of stakes which are driven into the lower supporting surface (generally the earth) so as to maintain a desirable shape for the curing concrete. The lower surface which supports the concrete slab must be suitably prepared ahead of time. Uncured concrete is heavy and it is not unusual to have additional stakes driven into the supporting media beneath the concrete slab at angles which are required to buttress the form in areas where it is misshapen and bent out of the desired shape so that it requires additional support. The concrete is held in this form until sufficient time has elapsed that it is cured sufficiently to allow the removal of the wooden forms.
This invention seeks to provide a form that is much easier to use, in that it is easier to set up, and yet does not impede the curing process of the concrete. It will be found that this form is easy to assemble by unskilled labour which contributes to its overall efficiency. Because this invention utilizes a metal form, means are incorporated for accurately locating the members composing this form.
This invention uses a permanent steel form which is held in the desired shape by the stiffness of the steel forms, which when coupled with the special threaded reinforcing bars (rebars) which extend across the form (in both directions) and through holes provided in the sheet steel forms (end plates and side plates) to hold the form sections of the form secure. Of course special nuts are threaded on to the ends of the threaded rebars. To help keep the cost of the form to a low value, unthreaded rebars are interspersed at intervals between the threaded rebars. It is understood however, that these unthreaded bars may or may not pass through apertures in the steel plates which are used to surround the concrete slab. In any event, these unthreaded rebars contribute nothing to the location of the steel plates surrounding the concrete slab.
In order to better understand the invention, a concrete slab of predetermined dimension is illustrated herein, it being understood that the dimensions of the slab have been clearly defined by the Supervising Authority beforehand.
In order to successfully design the slab of this invention it will be found that several of the values that are used in association with this invention have been predetermined beforehand. For instance the thickness of the slab normally will be specified by the designer of the slab. In no event will the thickness of the slab be less than four inches and greater than eight inches. Generally the thickness will be dictated by the National Building Code and/or by the Building Code in the area in which the slab is to be located.
The concrete form generally uses a steel form that has a vertical height of about six inches. This is a matter for the Designer of the form to decide. As soon as the Designer has determined the thickness of the Concrete Slab will be, he is ready to specify the vertical height of the steel framework. which will surround the concrete slab.
Any adjustment to the thickness is done using a foamed styro-foamed material known as “SM” which may be placed inside the steel form when it is decided to lesson the thickness of the concrete slab, or it is put under the steel form when it is decided that the concrete slab should be thicker than what was the thickness as originally projected.
Similarly the length and width of the slab will be set out in the specifications for the concrete slab. This helps the design process immensely. This invention uses the same (of the same dimension) shaped steel members for both the side plates and the end plates (to keep the costs down) of the designed form.
Referring now to
Referring now to
Each corner of the form will be provided with a splice piece shown as corner piece 72. Corner pieces 72 are provided with slots 74 and 76 for simple and easy adjustment. The corner piece splice plates, such as splice plates 72 are physically located by the passage of the threaded rebars through the holes such as 80 in the side plate 14 and holes such as 78 in end plate 12. Thus rebar 16 locates the position of side plate 14 (by passage through hole 80) and thence through slot 74 of the corner splice piece 72. Nut 82 is threaded on to rebar 16 to secure the position of end plate 14. Similarly the passage of threaded rebar 26 through holes such as 78 in end plate 12 and then through slots such as 76 in corner splice plate 72 serve to hold the corner of the form firmly in place.
The splice plates 60 for the side plates such as 12 and end plates such as 14 are attached to the form a little differently than the corner splice plates 72. Here the splice plates such as the splice plate 60 have a central hole 66 provided for the passage of threaded rebar (such as threaded rebar 20). This physically locates the side members of the form. Splice plates 60 are attached to the side plates 12 and end plates 14 by means of a pair of bolts such as those shown as 62 and 64 which pass through a pair of previously drilled holes 68 and 70 in steel side plates 14. This assures the proper spacing of the form members joined together by such a splice plate 60.
This form was specifically designed to be assembled quickly (and adjusted quickly) where unskilled labour is the only source of labour available. No expensive trenches need to be dug around the outside of the form; the slab simply floats on the reference medium. The form will be found to be exceptionally useful in far away locations in third world countries where only local help will be provided will be unskilled labour. Because the slab will always be weak in tensile strength the addition of the steel rebar to this invention merely serves to increase the strength of the resulting product.
Many modifications and other embodiments of the invention will come to mind of one skilled in the art, having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments Therefore, it is to be disclosed, and that the modifications and embodiments are intended to be included within the scope of the dependent claims.
