Units manufacturing slabs
Advancement towards this end has been the subject of research and investigations for many years. Discussion herein will be limited to road building but it will be understood that the same concepts and conditions apply to other concrete structures. Responsive to changes in temperature and moisture conditions in the atmosphere, total units of concrete undergo corresponding changes in volume and shape. Likewise, unequal distribution of moisture content, or temperature in the structure, causes unequal volume changes resulting in distortion and bucking of the concrete structure. If these volume changes are restrained, tremendous internal compression and internal stresses build up within the structure depending on the character of volume change. In flooring or in roadways, the development of such initial fractures and cracks initiates the destruction of the road.VIDEO ON THE TOPIC: Shuoyu quartz slab production line
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concrete slabs manufacturing machines
Advancement towards this end has been the subject of research and investigations for many years. Discussion herein will be limited to road building but it will be understood that the same concepts and conditions apply to other concrete structures. Responsive to changes in temperature and moisture conditions in the atmosphere, total units of concrete undergo corresponding changes in volume and shape.
Likewise, unequal distribution of moisture content, or temperature in the structure, causes unequal volume changes resulting in distortion and bucking of the concrete structure. If these volume changes are restrained, tremendous internal compression and internal stresses build up within the structure depending on the character of volume change. In flooring or in roadways, the development of such initial fractures and cracks initiates the destruction of the road.
When cracks are formed, the ability of the road for carrying the load is reduced, especially if the subgrade is insufficient. Once a crack has formed, spalling is permitted and this has the result of enlarging the openings and aggravating the damage. Water may enter the openings and cracks and reach down to the subgrade where mud is formed upon admixture with the materials of the subgrade. The mud thus formed can be pumped out by reaction to flexture of slabs on the road bed and vibration to the extent that the road bed will become undermined and slowly break down under external load.
The cracks that are developed fault to the extent that an uneven and undesirable roadway results. If the roadway becomes rough, the damage thereto is accelerated by normal use. Numerous techniques havebeen developed for the purpose of preventing or controlling the formation of cracks in concrete. Many of these systems employ frequent jointing with load transmission devices across the joints to provide for changes in the volume of the concrete in the attempt to remove the cause for cracking in the rst instance by dividing the slab into small section.
These have not been altogether successful and irregularly shaped cracks are still formed. Another method employs the use -of reinforcing bars of steel imbedded in the concrete. In fact, the linealfeet of cracking is not affected by the amount of steel embedded. However, the opening of the individual crack is held smaller by the increase in amount of steel reinforcing or, in other words, the steel reinforcing controls the cracks after they have been formed. Therefore, by the use of reinforcing steel bars, the intent is to restrain the enlargement of the cracks to the extent that infiltration of water and foreign material which causes spalling might be minimized or prevented.
Though successful in some degree, large quantities of steel are required and considerable expense is involved. Others have tried increasing the thickness and volume of the concrete slab that is originally formed so that external load will have less effect. The causes for cracking are not removed by this technique.
In fact, crack formation is increased by the larger dimension of the concrete structure. Another object is to produce reinforced concrete which uses high tensile strength steel in minimum amount for the purpose of preventing the development of cracks.
A further object is to employ the principle of poststressing of reinforcing steel members in the manufacture of concrete whereby the concrete is under compressive force in a direction to prevent formation of cracks. A still further object is to produce a roadway by laying down precast slabs of reinforced concrete, and it is a related object to manufacture precast slabs of concrete embodying means to prevent formation of cracks.
A still further object is to produce a concrete road, and to provide a method for manufacturing same, of prefabricated slabs of concrete with steel reinforcement stressed throughout its length by gravitational force generated as an incidence to the laying of the slabs. These and other objects and advantages of this invention will hereinafter appear, and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the 4accompanying drawing, in which- Figure l is a sectional elevational View illustrating concepts of this invention in the manufacture of the concrete structure;.
Pre-fabrication of unreinforced concrete structures for flooring and road beds and the like, using slip dowel joints, has been tried and abandoned where crackless surfaces are required because it was impractical. At the present time, road beds are usually prepared by pouring the cement mixture in place in position of use and then allowing the material to set. It is believed that a precast slab of concrete could be used if reinforcing with steel bars could be arranged to 'be continuously stressed throughout their lengths in the road bed.
Applicant has found la way to reinforce prefabricated concrete slabs and to achieve stressing of the reinforcing members throughout after the concrete has set and as an incidence to the laying of the pre-fabricated slab in position of use on the road bed.
Thus it has been made possible for the first time to build pre-fabricated roads with continuous stressing of the reinforcing steel bars in a manner which will prevent cracking during changes in volume and shape incident to normal operation and exposure to atmospheric conditions.
The production of such structures is a primary object of this invention and it is a related object to produce a precast concrete slab with the reinforcing members already imbedded therein in the desired relation. In the practice of this invention, a concrete slab'is cast with one or more smooth-walled steel bars arranged longitudinally through the interior of the slab.
The number of reinforcing steel bars employed depends chiefly upon the width and the cross section of the slab and the amount of reinforcement desired. For example, four units are employed in each of the slabs illustrated in the drawing. Means are provided on the ends of the bars for joining with the adjacent ends of the bars of slabs to be positioned endwisethereofjointing being effected while the slab to be positioned is tilted against the positioned slab so that gravitational force operating to lower the tilted slab in position of use may also be harnessed to stress the jointed reinforcing bars throughout their lengths in the endwise direction.
Anchors or stops should be provided to limit movement of the bars other than that effected by poststressing in the manner described.
In the modification shown in the drawing, each slab is formed with end walls 11 land 12, respectively. Each end portion has a rectangularly shaped cutout section 13 and 14, respectively, extending from the top of the slab to approximately the center portion thereof to make room for center placing of unbonded smooth wall reinforcing bars 15, and have one or more transverse bars 16, which 'are secured, as by welding, to the opposite ends 17 of the reinforcing bars On one end, just below the cutout section 13, the slab is formed with a projecting curvilinear shelf in the form of a substantially semi-cylindrical section 1S which may be adapted to extend all the way across the slab lil.
The opposite end of the slab is formed with a recess 19 of substantially the same contour as the shelf 18 and in the same relative position as the shelf. Further recesses 2t and 21 may be provided across the slab contiguous with the cutout sections 15 and 14, respectively, for anchoring a grout 22, when employed.
In assembly, slab B to be positioned in continuous alignment with slab A which is already properly located on the prepared subgrade 23, is placed with its recess 19 in contacting relation with the shelf 18 of a positioned slab A so as to enable the slab to be positioned to be tilted at a predetermined angle, as illustrated in Figures l and 3. While in this position, the free ends 17 of the longitudinal reinforcing bars 15 overlap so that they may be joined together, as by welding or the like, as illustrated in Figure l.
Slab B is then permitted to rock about the shelf 18 until it rests properly on the subgrade Such rotation may be eifected entirely by gravitational force or additional force may be applied if necessary. Rocking movement of the slab to its resting position stretches the connected reinforcing bars 15 and automatically generates longitudinal stress throughout their length in a poststressing technique. The joined transverse bars 16 act as stops or anchors for the longitudinal reinforcing steel bars 15 in the poststressing operation.
It is important to maintain an unbonded relation between the reinforcing steel bars and the concrete. For this purpose it is convenient to use smooth walled bars and to make use of lubricants or other slip agents on the metal surface, if necessary.
Rods 16 serve also as transverse unstressed members which are often used in reinforced paving slabs. The use of such unstressed transverse members is adequate to control longitudinal cracking because the road is narrow as compared to its length. In fact, it is suiiicient if such transverse members or rods are of small cross-section and firmly bonded to the concrete material. After the slab has been lowered to its position of use on the road bed, theopen notch 26 formed by the cutout sections 13 and 14 may be 'filled with a precast block 27, preferably coated with a cement slurry on the forward and rearward walls to establish a better bond with the slabs.
This is suggested to prevent or minimize entrance of moisture and foreign material into the road structure. Instead, the notch 26 may be filled with cement grout 22 which anchors in the recesses 20 and 21 provided and, when allowed to harden, provides a well integrated road structure. The amount and quality of reinforcing steel required for the practice of this invention is as little as one-third to one-fourth that which has heretofore been required in ordinary reinforcing, such as mild steel, by unstressed construction.
With the substantial elimination of cracks, the need of a base of granular or aggregate material is minimized since pumping no longer'constitutes an important factor.
It has been found that concrete slabs placed lengthwise and compressed by poststressing in the manner described will reduce tension stress and the resulting slab is able to support greater road per unit thickness. Thus the initial cost and the weight of the slab per unit area may be appreciably reduced while still maintaining the quality and the operating characteristics of the road structure or the like. By the use of slabs of reinforced concrete manufactured in sections which can be handled, mass production systems which save time, labor and material may be employed and constructions which are formed thereby can be used immediately after laying operation is completed.
This eliminates the need for the construction of expensive feeder lanes or by-passes which have no practical use after the road has been laid. As a result, one of thc major problems in road construction, that of initial shrinkage upon cure of the concrete, is overcome so that high maintenance cost and means for compensating for such shrinkage can be greatly reduced.
Pre-fabrication provides other economies and advantages, such as the possibility of laying roads throughout the twenty-four hours of the day with the result that the tie-up of machines and equipment can be greatly reduced.
Under the circumstances, it will be evident that the amount of sealer fluid that will be needed will be at a minimum. A road or the like employing precast, reinforced concrete slabs prepared in accordance with this invention enjoys considerable flexibility in that it can be extended from time to time merely by the further addition of slabs or the roadway may be repaired in an effective and simple manner merely by the replacement of slabs.
It will be understood that numerous changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims. The method of laying concrete roads as claimed in claim 1, which includes the additional step of filling the open space between slabs formed upon rocking the slab in position of use to provide a unitary structure.
In the method of laying concrete roads, the steps of providing precast slabs of concrete having a cylindrical shelf across the lower portion at one end and a receiving recess acmss a corresponding portion at the other end and having reinforcing steel bars extending longitudinally therethrough at a higher level than the shelf and recess and in unbonded relation with the concrete, tilting one slab upon the other while in position of use with the recess of the one slab resting upon the shelf of the other, joining the end portions of the adjacent steel bars while the tilting relation is maintained, and then allowing the tilted slab to rock toward position of use whereby the bars are gravitationally poststressed throughout their lengths.
These and other objects and advantages of this invention will hereinafter appear, and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the 4accompanying drawing, in which- Figure l is a sectional elevational View illustrating concepts of this invention in the manufacture of the concrete structure; Figure 2 is a perspective View of a precast slab of the type shown in Figure l; 'Figure 3 is a sectional elevational View similar to that of Figure l, showing modified means for joining reinforcing bars in their assembled relation, and Figure 4 is a perspective view in section of a slab of the type shown 4in Figure 3.
Y In the practice of this invention, a concrete slab'is cast with one or more smooth-walled steel bars arranged longitudinally through the interior of the slab. Y ln accordance with the practice of this invention, the formation of transverse cracks in the road bed are prevented by continuous compression exerted by poststressed reinforcing steel deployed in precast sections of concrete and joined together throughout their lengths. I claim: 1. USA en. Arcuate and curvilinear assemblies comprising tandemly arranged building blocks having degrees of rotation.
USB2 en. Method of forming, installing and a system for attaching a pre-fabricated pavement slab to a subbase and the pre-fabricated pavement slab so formed.
Method and forming, installing and a system for attaching a pre-fabricated pavement slab to a subbase and the pre-fabricated pavement slab so formed. AUB2 en. A foundation element, methods for the construction of prefabricated structures including these elements, particularly prefabricated tunnels, and prefabricated structures made by these methods.
Composite structural member with thin deck portion and method of fabricating the same. CAA en. CAC en. USB1 en. CNB en.
Profitable Granite Slabs & Tiles Manufacturing Unit for Sale in Karimnagar, Telangana
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Prestressed concrete equipment and plants of machinery to manufacture prestressed beams and hollow core slabs. Vineyard and fence posts, lintels, simple T beams, double T beams, hollow beams, double beams, solid slabs, hollow core slabs for flooring or for wall panels, terrace units for stadiums, TT slabs…. Whereas the normal hopper contains the usual grey concrete and is designed for the manufacture of hollow core slabs, this third hopper is loaded with colourised concrete a mixture of sand, coloured aggregates and white cement. As well as the extended frame the machine also has a.
Precast Concrete Deck Slabs
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Phase-change processes produce a solid part from liquid material. They include the commercial processes of metal casting, infiltration of composites, and injection molding of polymers. These processes may reside early in the process stream e. Control of the part shape and workpiece microstructure to specific levels is a high priority in these processes and often establishes the economics of the manufacturing process. This chapter discusses the phase-change processes used to process metals, polymers, and metal-matrix composites. Manufacturing processes that change the phase of metals by melting and subsequently resolidifying materials into finished or semifinished products are categorized as molding and casting processes.
Choosing to use Ducon Concrete Ltd. View Video. Prestressed Slabs. Quality Controlled Products — Prestressed slabs are CE approved and manufactured in a controlled environment.
The phrase "reinforced sufficiently to ensure its integrity" used in this paragraph means that a registered professional engineer, independent of the engineer who designed and planned the lifting operation, has determined from the plans that if there is a loss of support at any jack location, that loss will be confined to that location and the structure as a whole will remain stable. By Standard Number Part Number:.
Precast core floor slabs
Slab Formwork. But with contractors always looking for a way to build faster and with higher quality, formwork manufacturers have come up with a variety of systems to increase efficiency and productivity in deck forms. The reinforcement in slab if specified in the structural drawing should be placed.
The book discusses different topics of industrial and production engineering such as sustainable manufacturing systems, computer-aided engineering, rapid prototyping, manufacturing management and automation, metrology, manufacturing process optimization, casting, welding, machining, and machine tools. The contents of this book will be useful for researchers as well as professionals. A Review. A Step Towards Swachh Bharat. An Experimental Approach. A Critical Review.
Production plant for pre-stressed concrete slabs
Account Options Sign in. My library Help Advanced Book Search. The book discusses different topics of industrial and production engineering such as sustainable manufacturing systems, computer-aided engineering, rapid prototyping, manufacturing management and automation, metrology, manufacturing process optimization, casting, welding, machining, and machine tools. The contents of this book will be useful for researchers as well as professionals. Selected pages Page Page
Technical specifications: 7 pouring compartments, size: 3. Work platform, stairs and railings including external vibrators and 1 frequency converter and controller 1 hydraulic unit to close the battery mold 1 built-in heating register in outer and movable partitions. Mould No.
Corporate tax rate cuts: New contract manufacturing units eligible for 15 per cent tax benefit
Panels of paving granite is a high-quality material for the improvement of urban areas and private estates. They can have a rectangular, square, and also other shape triangles, polyhedra, curved and radial elements. Granite slabs for paving differ in the form of the front surface sawn, heat-treated, bucharded or other texture , color scale and thickness from 30 to mm.
QUARTZ STONE: Know more about Engineered Quartz Stone - MORBI | Tiles manufacturing hub of India
Cordeel offers a quality precast concrete service to the civils and building market sectors in eight countries in Europe. Examining paving blocks and slabs as well as sorting out defective specimens on the dry side are found amongst the activities that still have to be painstakingly carried out manually in many concrete production facilities. This procedure is susceptible to error and no longer up to date.
In order to provide a better surface solution for their existing building material customers, several factories of Morbi have started manufacturing unit for quartz stone. Quartz stone is now much preferred for any type of building surfaces: kitchen top, vanity top, bench-top, platforms, floors or walls. Below we are proving some useful information for this new generation building material. What is a need of "making a stone" in factory?
Precast Concrete Deck Slabs. Millions of square feet of suspended concrete slabs are placed every year in the U. Full-depth precast deck panels are a promising alternative to the conventional cast-in-place concrete deck. Standard products such as railroad ties, decks and beams are shaped in one distinct way. Heavy duty precast concrete railway slab; Precast concrete wind turbine foundation; Retrofit factory floor or roof slab; Conveyer platform; We carry DTE size transformer pads and cabinet pads for the communication industry. Welcome to Pompili Precast Concrete.
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