THE PATENTS ACT, 1970

(39 of 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION

(See Section 10 and Rule 13)

Title of the invention:

METHOD AND SYSTEM FOR IN-SITU CONSTRUCTION OF CIVIL STRUCTURES

Applicant:

Kailas Suresh Kenjale

22 Parvati Gaon, Pune 411009

Maharashtra, India

The following specification describes the invention and particularly the manner in which it is to be performed [001 ] FIELD OF THE INVENTION

[002] This invention relates generally to civil engineering technology and

particularly to construction assemblies and execution methods and applicable to in-situ construction of precast, moment-resisting structural framework of civil constructions such as buildings.

[003] BACKGROUND OF THE INVENTION

[004] Conventional civil construction techniques entail different processes

comprising preparation of RCC / steel framework, casting of foundation, casting load bearing members like beams and columns, casting of floor slabs and finally, forming wall panels by layering bricks and cement-mortar mix. All these activities are resource-intensive in terms of labor, time and material costs.

[005] Steps involved in conventional methods of construction are sequential and not simultaneous. They include stages of laying foundation, casting beams and columns, casting floor-slabs, layering of bricks and cement-mortar mix to build filler walls. This process is repeated for each floor. Thus interdependence of the various stages of construction & involvement of skilled manual labor work in unprotected site environment, increases construction time and costs. Construction of RCC or steel framework first and then to infill it with filler walls makes the structure heterogeneous in material behavior and structural performance. This means that the joint in-between is the crux of structural integrity. As this joint is not made at same time of casting of beams, columns and walls, or is of a material composition different than that of its adjacent members, the material homogeneity and thus, structural continuity and integrity of construction are lost.

[006] Also, in general, concrete elements like beams and columns are casted in- situ with the help of plywood or steel plate forms These forms are supported with steel or wooden bracings & props. After curing, the formwork is stripped down. These forms require extensive bracing as well as shoring. This process is time consuming, requires intensive skilled /unskilled labor, and the quality output is subject to individual skill levels, and environmental factors like water quality, temperature variations, wind pressure , inconsistency in curing .

[007] Thus, the conventional construction methods have many shortcomings like heterogeneity of materials and load distribution, bulky sizes of members, interdependence of operations, heavy consumption and wastage of materials, labor and time. Also, these techniques tend to be non eco-friendly and are characterized by uncertainty of actual time required for construction.

[008] As far as short span floors are concerned, ribbed slab is a very effective way of reducing the steel & concrete requirement in the floor decks/slabs, but the design is very difficult , time consuming & costly as far as formwork and preparing & laying reinforcement is concerned.

[009] PRIOR ART

[010] Methods and systems to overcome the said problems of art find mention in prior art.

[01 1 ] One of the methods for overcoming the above mentioned problems is the use of preformed wall members. Patent document number WO/2003/097950A2 discloses a method for in-situ civil construction wherein preformed wall members are first temporarily supported in desired positions by support means and then the building vertical support pillars are cast using suitable surfaces of the preformed wall members made of regular concrete as framework. However, due to the heavy weight the manufacture, storage and transport of preformed wall members is cumbersome. Time and cost involved in these processes is a disadvantage in addition to requirement of technical experts who alone can fit and maintain alignment of these wall members. Also, the wall members do not provide any heat or sound insulation. This system also requires substantial temporary support while erection, Due to use of regular concrete wall element & a precast beam , the wall module is very difficult & time consuming in the erection stage. The wall module also lacks inclusion of any supporting devices like RFID, laser for a safe, accurate & speedy guiding & positioning system. The system also requires scaffoldings to complete the formwork of the pillar from the exterior of the building. All these factors substantially increases the cost, time & risk during erection work.

[012] Patent document number WO/2004/042163A2 discloses a method of constructing wall panels. This method uses two outer wire mesh members enclosing a middle member which consists of nine wire trusses and eight polystyrene foam pieces arranged intermittently in a panel. The outer members act as screed and also serve as scaffolds for finishing the panel with plaster. This invention provides for construction of ready-to-use wall panels but suffers from the disadvantage that its capabilities cannot be migrated to in-situ construction of different structural layouts. Also, use of these panels does not obleviate the material heterogeneity between walls, floors and the load-bearing members and therefore has low structural integrity of construction.

[013] Use of alternative material towards improvisation in construction technology has been commonly reported in literature. Use of reinforced cement for increasing strength and durability of construction is common. However, this method suffers from a setback of high weight to strength ratio, besides being intensive in regards of costs incurred.

[014] In general, prior precast concrete stay-in-situation forms have been ineffective due to

1 ) They are made with regular rebar reinforcement & thick sections of concrete, hence manufacturing efforts & labor involvement in manufacturing is more.

2) The design e.g inclusion of shear keys demands mold casting only, hence manufacturing speed is limited.

3) Since walls are to be constructed / erected separately the overall building erection/construction time is substantially more.

4) The beams are not slotted so they need extra efforts and cost to receive & engage ribbed slab.

5) Preparation of rebar mesh for slab/deck formwork needs onsite efforts & increases the actual construction time.

6) The available systems comprise either lightweight concrete panels OR semi precast stay in place systems , no system has a combination of both. [015] Thus, the methods and systems of the prior art have not been able to satisfactorily address the said problems which has been the focus of research for the present inventor, who has come up with novel solutions to the same. These solutions are neither covered nor anticipated by prior art.

[016] OBJECTS OF THE PRESENT INVENTION

[017] The current inventors have come up with mechanisms and systems to overcome the said problems of intensive requirements of time, skilled labor, cost and limited structural integrity achieved in conventional in-situ and / or precast construction techniques.

[018] It is an objective of the present invention to develop a building system comprising lightweight thin precast concrete stay-in-situation column & beam forms assemblies/modules in which the beam forms will come with rebar cages & column forms will receive the cages which are erected on site.

[019] It is an objective of the present invention to develop a building system which comprise wall modules which requires substantially less temporary support during erection phase.

[020] It is an objective of the present invention to develop a building system which comprise wall modules which are substantially lighter in weight & which requires substantially less time , efforts & cost during transportation & erection.

[021 ] It is an objective of the present invention to develop a building system which comprise wall modules which are easy to accurately position in a desired place without any damages & with increased safety.

[022] It is an objective of the present invention to develop a building system which do not require any scaffolding from outside the building for formwork erection.

[023] It is an objective of the invention to develop a method of erecting wall assemblies/modules & casting the columns, so that there is hardly any need of temporary supports.lt is another objective of the present invention to develop a building system which includes a lightweight concrete wall portion which is casted within the boundry of the column & beam form assembly.

[024] It is another objective of the present invention to develop a building system comprising a precast concrete form which substantially reduces bracing and shoring requirement & waste generation. [025] It is another objective of the present invention to develop a building system comprising a lightweight precast concrete wall & form assembly that substantially reduces the dead weight of the building.

[026] It is another objective of the present invention to develop a building system that substantially reduces the construction time & labour required for a midrise or high rise residential or hotel /hostel building.

[027] It is another objective of the present invention to develop a building system which contains precast ,stay in situation deck form assembly as flooring deck/slab which makes a composite lightweight ribbed floor that is integrated to beam and column structure during pouring of the cast-in- situation concrete and creates a lightweight slab which does not require plaster or gypsum board from the bottom..

[028] It is another objective of the present invention to develop a building system which creates a substantially lightweight building which offers substantial reduction in requirement of steel in case of midrise and high rise buildings.

[029] It is another objective of the present invention to develop a building system which includes wall assemblies which are ready with windows/window frames , safety grills, electrical conduits, cables, plubing, sensors etc.

[030] It is another objective of the present invention to develop a building system which includes wall & deck assemblies which are ready for paint.

[031 ] It is another objective of the present invention to develop a building system which includes wall assemblies which offer substantial heat & sound insulation and which are watertight.

[032] It is another objective of the present invention to develop a flexible but dimensionally stable , ladder type grid of plurality of stay in situation rebar forms & plurality of rebars required for reinforcement of deck//slab .

[033] It is another objective of the present invention to develop a floor deck/slab formwork panel subsystem which is modular in nature, which is supported by the stay in situation rib forms & which requires minimum amount of shoring which can be used for any kind of commercial, parking, industrial use.

[034] These objectives are accomplished by developing lightweight composite stay-in-situation column/beam forms and precasting these forms with lightweight cellular /foamed concrete to form wall assemblies, the forms may come with rebar cages or without ,the forms will receive cast-in-situation concrete to form a monolithic RCC structure. Further, the said objectives are accomplished by developing a lightweight composite stay-in-situation deck form which also may come with or without rebar cages & reinforcing mesh, enabling a method of erecting & positioning these assemblies, providing the minimum necessary shoring, casting the concrete in-situation, and removal of the shoring.

[035] Rest of the objectives and benefits of the present invention will be seen in the further explanation in conjunction with the accompanying sketches wherein it is set forth by way of example and illustration, one embodiment of the present invention.

[036] SUMMARY OF THE INVENTION

[037] The present invention provides for a building system which comprises two subsystems, one is, precast assemblies comprising stay in situation column /beam forms of fiber reinforced concrete or any other composite material and lightweight concrete and /or EPS cored wall segments and other subsystem, which is a lightweight ribbed floor slab/deck subsystem which further comprises stay-in-situation rib forms made of fiber reinforced concrete or any other composite material & embedded with rebar cages & a plurality of rebar connected to it in a ladder like fashion with a dimensionally stable but flexible element for reinforcement of the slab which help create a lightweight monolithic RCC building structure with the help & benefits of lightweight precast components , within shortest possible time.

[038] Both of the above subsystems may work independently or jointly in conjunction with some other building system/systems and are meant for mid- rise & high rise residential /hotel/hostel buildings where room spans are comparatively shorter to commercial concerns. The system outlined by the present invention is meant for all seismic zones.

[039] BRIEF DESCRIPTION OF THE DRAWINGS

[040] FIG. 1 is a perspective view of a building being constructed using the precast stay in situation building forms & system which is the subject of this invention. [041 ] FIG. 2 A & B is a perspective view of a precast beam form & precast column form of the subject building system.

[042] FIG. 3 shows sectional views of various types of precast stay in situation column & beam forms.

[043] FIG. 4 is an elevation view of the precast wall assembly which is part of the subject building system.

[044] FIG. 5 Is a perspective view of a wall assembly where a beam form is shown which is slotted to receive & engage the deck/slab rib forms.

[045] FIG.6. Is an elevation view of the external decorative side of the wall assembly.

[046] FIG.7. Is a sectional top view of the bottom part of the peripheral wall assembly.

[047] FIG.8. A Is a top view of the precast stay in situation rib form.

[048] FIG.8. B Is a side elevation of the precast stay in situation rib form.

[049] FIG .9. A & B are top & sectional view of the assembly of plurality of precast stay in situation rib forms and plurality of rebars connected to each other.

[050] FIG.9. C is the sectional view of the Rib forms & rebar assembly in transit.

[051 ] FIG.10.A is a cross sectional view of a deck/slab formwork & its supporting assembly.

[052] FIG.10.B. Is an elevation view of a formwork support beam.

[053] FIG.10. C. Is a three dimensional view of a formwork support beam.

[054] FIG .1 1.A,B,C are different types of ceiling panels to be inserted between the floor deck/slab ribs.

[055] DETAILED DESCRIPTION

[056] According to this invention a building structure as in FIG. 1 , is constructed of precast assemblies comprising column formsi & beam forms 2with rebar cages & walls 3 and ladder type interconnected flexible grid comprising precast/prestressed rib forms & rebar reinforcement and cast-in- situation concrete . The floor deck/slab ,may or may not be a ribbed deck/slab.

[057] The Precast wall & form assemblies are preferred for the construction of mid-rise and high-rise buildings in all the seismic zones. The wall form assembly & rib form assembly 12 in combination with cast-in-situation concrete 16 form a building system that can be designed as a normal monolithic reinforced concrete structure for buildings located in any seismic zone. For any high-rise building located in a potential higher seismic activity or high wind load to provide lateral load resistance ,a cast in-situation or precast shear wall assembly may be utilized The shear walls can be located anywhere in the building. Fig 2A shows a precast beam form & Fig2B shows a precast column form .Generally which will come with various cross sections which are shown in figure 3. The column form is generally rectangular in cross section The width to length ratio of the said rectangle is generally 1 :2 & atleast it should be 1 :1.5 The longer side of the cross section is perpendicular to the wall surface This will ensure better stability during the erection stage & will require substantially lesser temporary support ,as well as will increase the speed & safety of the erection process. Both or either of the forms are assembled to a lightweight concrete wall element , the beams are later fitted with rebar cages with spacers/connectors 46 which helps the rebar cage & form to tightly hold & support each other and then the forms are filled with cast in situation concrete to form beams , columns & resultant part of the building structure as shown in Fig 1. The beam spans can attain the maximum length attainable as in case of a totally cast in situation system. The concrete forms are made of fiber reinforced concrete or aerated autoclaved concrete or any other lightweight composite material which may or may not contain chicken mesh but a steel wire lath 10of appropriate thickness & dimensions is bonded in the external side wall7 of the column /beam form which comes out from the end of the side wall. The base 8 of the column/beam form may or may not have plurality of circular punctures in it which are maximum 100mm in diameter. The column form may have holes 47 near the edge to receive & engage fastening clamps. The column & wall forms may come in various cross sections which are represented in fig 3 but are not limited to as shown there. The beam forms may have arrangement to engage the spacers which will correctly position and tightly integrate & hold the rebar cage with the form. The column forms ,beam forms & wall assemblies are cured in the factory in a controlled environment till a specific strength is achieved The wall assemblies on the external periphery of the building may have a notch 23 or groove 24 along the periphery as shown in fig 7. The external side wall of the beam form on the external periphery of the building may have a tongue 1 1 like portion at the upper end which is shown in fig..3. Some column forms may have a ledge ^" ! 2 like portion along the one or two vertical edges of the column form face as shown in fig 3. Some column forms may have side walls7 which are zig zag along the vertical edge & the reciprocating column forms may have similar zig zag shape which will complementarily fit in to this shape.

[059] Fig 4 shows a typical assembly /module comprising column form 1 beam form 2and wall element 3 the wall element is preferably casted using light weight cellular concrete or foam concrete or is assembled of aerated concrete panels or 3d expanded polystyrene panels. The wall assembly /module may or may not include a window frame 17 safety grill 18 & window seal 19.

[060] The column & beam forms or the wall element may be embedded with RFID or other chips which be stored with the following information like in parts or in full in digital format- structural characteristics of the building, floor, module , element like weights, loads, forces, layout of the conduting, piping ,cabling, embedded in the wall, drawings/designs/dimensions of the building, floor, that particular assembly/module , element, Position of reference points where laser beam/plane creating devices are to be mounted at specific points on the assembly/modul, element. Any other information which may be usefull for transportation, distribution, erection, guiding & positioning, construction, & maintenance .

[061 ] At the said specific points on the wall modul/assembly , element .punctures or grooves or any other appropriate arrangement is created ,which will firmly & precisely hold & engage , laser beam /plane creating device. Or any other device which will be useful in identifying that reference point by the guiding & positioning system.

[062] Fig 5 shows an assembly/module comprising a wall element 3 and a slotted beam form 20 the beam form has slots 21 to receive and engage the precast rib form ssemblies which are shown in fig 9 the slots are correct in dimension so as t o receive and engage the beam assemblies. The upper corners of the slots are also semi circular in shape.

[063] Fig.6. shows again an assembly /module comprising a wall element3 and column forms 1 and beam form 2 which may have a texture of stone, bricks or any desired object/ set of objects 22 . The texture may be created using rubber molds or form liners or molds or form liners made of any appropriate material like expanded polystyrene or as such.

[064] Fig.7. Shows the wall assembly on the external periphery of the building which may have a notch 23 or groove 24 along the periphery at the bottom end of the assembly/module. The cross sectional views 23,24 of the assembly/module represents few of the possible arrangements at the bottom

[065] Fig 8A shows a cross sectional view of a precast stay in situation rib form made of fiber reinforced concrete or aerated autoclaved concrete or any other lightweight composite material.

[066] Fig 8B shows the side elevation of the said rib form. The rib form contains a rebar cage 26. The main body 25 of the rib form is generally U shaped having two side walls40 and a base 41 The rib forms are manufactured in factory using either slip form technique or concrete extrusion technique or any other appropriate technique. The rib forms are cured in the factory in a controlled environment till a specific strength is achieved.

[067] During the manufacturing process of the forms groves 31 are created to receive & hold the ceiling panels which are shown in fig 1 1. During the manufacturing process a plurality of punctures 30 are created in the side walls of the form, the punctures are circular in shape & they are intended to receive and engage a modular floor deck/slab form support assembly which is shown in fig.10. The rebar cage is tightly held & connected with the main body of the rib form using spacers/connectors. The upper part of the side walls of the main body ,on it's external face has a plurality of holes to hold & engage dowels 28 made of plastic or fiber composite material .During the manufacturing process ,on the top face of the side walls of the rib form; at specific intervals, a plurality of spacers 29 are embedded .

[068] The spacers hold the rebars which are part of a ladder type interconnected flexible grid. The bottom of the rib form is marked with paint 32 at specific intervals on the external face. [069] Fig 9A .Is a cross sectional view of the ladder type assembly/ grid of plurality of rib forms 35which are embedded with rebar cages 26, plurality of rebar 33 which are part of the reinforcement for the cast in situation floor deck/slab and plurality of flexible and dimensionally stable binding elements 34 which binds the rib forms, cages, & rebar all together.

[070] Fig 9B is a top view of the said ribs assembly and Fig 9C shows the cross sectional view of the said ribs assembly during transportation. The ribs assembly is manufactured in the factory as per fig 9A and/or fig 9B and then it is arranged for transportation & is transported to the site as shown in Fig9C .It is erected using a crane and a lifting device . It is correctly positioned between the receiving framework of slotted /regular beams, and the ribs are engaged and rested in the slots of the receiving beams.

[071 ] Fig 10 A. Is a cross sectional view of a deck/slab formwork assembly. The slab form work panels 35 which are made of either plastic or any fiber composite material or a film faced board is initially rested on the dowels 28.The support beams 36 are connected to the bottom of the panels35. The slotted support beam 37 is made of plastic or fiber composite material. It has slots to receive and engage support beam 36. The slotted support beam 37 also has plastic dowel shaped parts 42 which are structurally integrated with the support beam. The plurality of these dowels are of such dimensions & locations so that they can exactly pass through & fit into the pipes embedded /holes 30 in the rib form . The slots of the support beam 37 are engaged with the support beams 36 and the support beam 37 is pushed towards the rib form The dowels 42 are passed across the rib form through holes 30 and across the reciprocating supporting beam 38 which is similarly touching the opposite wall of the rib form. Both the support beams 37 & 38 are touching the opposite walls of the rib form and are tightened & locked with the help of a lever type arrangement 39. Fig 10 B is a cross sectional side elevation of the formwork support assembly and Fig 10C is a perspective view of the support beam 37 of the formwork support assembly.

[072] Fig 1 1 A , Fig1 1 B & Fig 1 1 C all are cross sectional views of different types of ceiling panels fitted in place utilizing the support of the casted ribs .The ceiling panels are made of gypsum or expanded polystyrene or any other composite material or any other appropriate material A ledge like portion 44in the vertical side wall 45 of the ceiling panel is fitted in the grooves 31 on the external face of the side walls of the rib form. The plurality of the dowels, dimensions & their locations are so chosen that they can exactly pass through & fit into the pipes embedded /holes in the rib form. The slots of the support beam are engaged with the support beams and the support beam is pushed towards the rib form The dowels are passed across the rib form through holes and across the reciprocating supporting beam which is similarly touching the opposite wall of the rib form

[073] ADVANTAGES AND APPLICABILITY

[074] As evident from the foregoing description, it shall be appreciated that the present invention has numerous advantages on account of its novel features; the notable being

• use of light weight foamed concrete for construction which saves stress on load bearing members

• use of fly ash rather than lime based methods for manufacture of concrete which saves on pollution, reduces harmful emissions, lowers costs of production and provides for higher speed and ease of quality construction

• use of beam forms in lieu of beams, thus alleviating necessity of the heavy beams while improving on the speed and ease of erection of the construction

• positioning of beam form at top of the module, thus leading to better floor efficiency

• achievement of monolithic construction which has inherent structural integrity and material homogeneity

• waterproofing and aesthetics of construction are preserved

[075] It would be evident to the reader skilled in the art that these, and other advantages are neither comprehensively provided nor anticipated by methods and systems of prior art.

[076] The invention is more easily comprehended by reference to the specific embodiments recited hereinabove which are representative of the invention. It must be understood, however, that the recited embodiments are provided for the purpose of illustration, and that the invention may be practiced otherwise than as specifically illustrated without departing from its spirit and scope. As will be realized, the present invention is capable of various other embodiments and that its several components and related details are capable of various alterations, all without departing from the basic concept of the present invention. Accordingly, descriptions will be regarded as illustrative in nature and not as restrictive in any form whatsoever. Modifications and variations of the system and apparatus described herein will be obvious to those skilled in the art. Such modifications and variations are intended to come within the scope of the present invention.

DATED THIS 17TH DAY OF AUGUST, 2010

Rohit Deshpande

[Agent for the applicant, registration number IN/PA-1389]