EP0698153B1 - Method and apparatus for staged vibration of concrete - Google Patents
Method and apparatus for staged vibration of concrete Download PDFInfo
- Publication number
- EP0698153B1 EP0698153B1 EP94913683A EP94913683A EP0698153B1 EP 0698153 B1 EP0698153 B1 EP 0698153B1 EP 94913683 A EP94913683 A EP 94913683A EP 94913683 A EP94913683 A EP 94913683A EP 0698153 B1 EP0698153 B1 EP 0698153B1
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- EP
- European Patent Office
- Prior art keywords
- concrete
- boundary layer
- vibrations
- mass
- concrete structure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/22—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for consolidating or finishing laid-down unset materials
- E01C19/30—Tamping or vibrating apparatus other than rollers ; Devices for ramming individual paving elements
- E01C19/34—Power-driven rammers or tampers, e.g. air-hammer impacted shoes for ramming stone-sett paving; Hand-actuated ramming or tamping machines, e.g. tampers with manually hoisted dropping weight
- E01C19/40—Power-driven rammers or tampers, e.g. air-hammer impacted shoes for ramming stone-sett paving; Hand-actuated ramming or tamping machines, e.g. tampers with manually hoisted dropping weight adapted to impart a smooth finish to the paving, e.g. tamping or vibrating finishers
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/02—Conveying or working-up concrete or similar masses able to be heaped or cast
- E04G21/06—Solidifying concrete, e.g. by application of vacuum before hardening
- E04G21/063—Solidifying concrete, e.g. by application of vacuum before hardening making use of vibrating or jolting tools
- E04G21/066—Solidifying concrete, e.g. by application of vacuum before hardening making use of vibrating or jolting tools acting upon the surface of the concrete, whether or not provided with parts penetrating the concrete
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/08—Producing shaped prefabricated articles from the material by vibrating or jolting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/08—Producing shaped prefabricated articles from the material by vibrating or jolting
- B28B1/093—Producing shaped prefabricated articles from the material by vibrating or jolting by means directly acting on the material, e.g. by cores wholly or partly immersed in the material or elements acting on the upper surface of the material
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/02—Conveying or working-up concrete or similar masses able to be heaped or cast
- E04G21/06—Solidifying concrete, e.g. by application of vacuum before hardening
- E04G21/063—Solidifying concrete, e.g. by application of vacuum before hardening making use of vibrating or jolting tools
Definitions
- the present invention generally relates to a method and apparatus for introducing vibrational energy into plastic concrete structures which are generally oriented horizontally, (such as concrete slabs, decks, roadways and similar or related concrete structures), in successive stages or increments.
- Staged Vibration means, subsequent to the pouring of a concrete mass, the introduction of vibrations into the concrete mass in such a manner that the lower portions of the mass are first consolidated, and the sequential modification of the character of the vibrations so as to cause successively higher portions of the concrete mass to become consolidated, until all or nearly all of the concrete mass is consolidated into a single mass of uniform density.
- the present invention is a method of placing concrete using staged vibration of the concrete by employing a vibration-producing apparatus which is in contact with a concrete mass, (either by submerged devices, or by devices in contact with the surface of the concrete mass, or both), in a staged, stepped or phased sequence.
- vibrations are introduced to a concrete mass in sequential timed "stages", with the number of stages, the amplitude and frequency of the vibrations, the time-duration of each stage, and the relative orientation of the vibration-producing devices each being variable, depending upon the physical characteristics of the concrete mass.
- the pertinent physical characteristics of the concrete mass include, but are not necessarily limited to: The physical characteristics of the concrete being used; the thickness of the slab (or other structure) being placed; and the specific materials incorporated into the concrete during formation of the concrete mass.
- a problem with prior methods of placing concrete using vibrators is associated with the lack of control of the vibrators.
- any one section of a poured concrete slab is vibrated too much, it causes hard spots in the concrete slab approximately at the location of the contact with the vibrator.
- over-vibration of the concrete can also cause aggregate separation in the vicinity of the vibrator. Aggregate separation and "hard spots” both results in a non-uniform and weakened final slab.
- prior concrete placing operations typically cautiously "under-vibrate” the concrete mass or may not vibrate the concrete mass at all.
- Another known procedure involves the use of slip forms in which the concrete mass placed in the forms may or may not be vibrated by a continuously moving form into which, or in front of which, the concrete is poured and provided with a specific shape which is maintained after the form moves progressively, with the concrete then being finished using conventional procedures.
- the principal purpose of vibrating plastic concrete in this context is to expeditiously consolidate the concrete mass to its maximum and at as nearly a uniform density as possible by encouraging and assisting the upward migration of water and air which would otherwise migrate slowly or not at all. Entrapment of air and water weakens the concrete and the slow migration of these materials extends the time required to place and finish the mass.
- Existing procedures for the application of vibrations to the concrete mass provide virtually no means to control or to modify the vibrational characteristics of the vibrators (other than by manually turning the vibrator off and on), and no means to control or modify the length of time the vibrators act upon the concrete mass in which the control means is based upon the degree of accomplishment of the end result desired. Therefore, the existing procedures produce a concrete mass in which the degree of consolidation varies from one location to the other and in which the time required for water to evaporate from the surface varies from one location to the other.
- Another phenomenon associated with natural (i.e. non-vibrated) consolidation and curing of concrete is the entrapment of moisture inside of the curing mass.
- concrete mixtures commonly comprise an amount of water far exceeding the quantity which is actually necessary to effect proper curing and maximum strength of the concrete mass.
- the excess water is intentionally added to the concrete mixture in order to facilitate transporting, pouring, forming, and finishing operations. If left stagnant (i.e. un-vibrated), pressure from the weight of the concrete mass initially slowly presses some of the excess water upward through the concrete mass, thus initially inducing migration of some of the excess water towards the surface of the slab and, at the same time, effecting the consolidation of the concrete mass near the bottom of the slab.
- de-watering techniques are used wherein the concrete mass is poured and formed into a structure having an upper surface, and the mass is then de-watered by applying a vacuum water extracting system over the wet concrete surface.
- the surface of the concrete mass is de-watered by placing absorbent material (such as burlap or the like) over the wet concrete surface, and then spreading a desiccant (such as dry cement) on the burlap.
- absorbent material such as burlap or the like
- a desiccant such as dry cement
- the surface In highway construction, the surface is generally not required to be smoothly finished, with vibration and strike-off being all that is usually required. While this is essentially a machine operation, the end product (the concrete slab) is not uniform because the delivered materials forming the concrete mass are not uniform and the vibration and strike-off equipment do not adjust in any way to compensate for this lack of uniformity.
- highway concrete is de-watered only by gravity (and evaporation). Accordingly, water removal from highway slab is typically a slow, uneven and uncontrolled process. Water removal from highway slabs in the described a slow, uneven and uncontrolled manner results in uneven shrinkage of the slab as it cures, and ultimately resulting in cracks and a weakened structure.
- Another objective of the present invention is to provide a method and apparatus of placing concrete slabs, or similar structures, of the character described in which the uncured concrete mass is sequentially consolidated from the bottom upward toward the top surface, so as to effect a placed structure of substantially uniform density from the bottom to (or nearly to) the top, wherein the consolidation and integration of adjacent horizontal layers of the concrete mass is effected by a vibrator apparatus which advantageously imparts vibrations into the uncured concrete mass.
- Another objective of the present invention is to provide a method and apparatus of placing concrete slabs, or similar structures, by the use of machine operations in which the rate of hardening of the concrete mass is somewhat controlled by a plurality of "stages" (or series of vibrations of the concrete mass), with each "stage” affecting only a portion of the total thickness of the concrete mass.
- Another objective of the invention is to provide a method and apparatus of staged vibration of concrete in which variably controlled vibrations are introduced into or upon the concrete mass in successive stages so as to cause the elevation of said boundary layer, (or more specifically, the height of the sufficiently-consolidated, relatively drier, uncured concrete mass) to rise at each "stage", with the number of vibration stages applied to a particular concrete mass being determined by the thickness of the mass and other physical characteristics thereof.
- a further objective of the invention is to provide a method and apparatus of determining the location of the boundary layer o between the relatively dry, firm, consolidated concrete in the lower portion of the concrete mass and the relatively wet, soft concrete in the upper portion of the concrete mass, so that the vibrational characteristics such as frequency, amplitude, and duration can be adjusted in order to cause the boundary layer to assume a uniform depth beneath the surface of the concrete mass.
- a further objective of the invention is to provide a method and apparatus of staged vibration of concrete in accordance with the preceding objectives in which the staged, stepped or phased vibration procedure described in the preceding objects results in migration of water to the surface of the concrete mass, and wherein the accumulated water on the surface of the concrete mass can be removed by mechanical means (such as by vacuuming), thus providing a uniform surface to the slab which enables surface-finishing operations to be advantageously performed automatically by machine.
- Another object of the invention is to provide a method and apparatus of the character described which is operationally effective for use in any concrete slab of conventional thickness in various conditions, including interior slabs for buildings; slabs that may be either on grade or elevated; slabs for highways, bridges, sidewalks and the like; and slabs either of single thickness or integrally or monolithically topped, thus enabling the unique method to be utilized with many concrete structures.
- FIG. 1 of the drawings illustrates a concrete mass (generally indicated “M" in the figures) which may be in the form of a slab as the concrete has been poured into a form (not shown) or the like from any suitable source onto a slab sub-base B.
- the concrete mass M typically includes aggregate, cement, water and other additives which may conventionally be employed in concrete slabs.
- the aggregate, cement, water and other materials incorporated into the concrete are typically randomly distributed throughout the thickness of the concrete mass M between the sub-base B and the exposed top surface 1 of the concrete slab.
- the concrete is mass M is first poured, virtually none of the concrete mass is sufficiently consolidated and dry enough for purposes of finishing the top surface 1 of the slab.
- Such variation in consistency of poured concrete is not crucial to the operation of the present invention, but, as will be appreciated by those skilled in the art, is an inherent property of randomly mixed concrete.
- finishing zone 7 which preferably is no more than 1/4 inch thick.
- migrated water may collect throughout the placing operation.
- finishing operations (which will be described in more detail later) may be used which effect a relatively higher concentration of "fines” and “superfines”, and a relatively lower concentration of aggregates in the finishing zone 7 than in the rest of the concrete mass M.
- boundary layer L Between the relatively more consolidated, relatively more firm and relatively drier concrete M1 near the bottom 2 of the slab and the relatively less consolidated, relatively less firm and relatively less dry concrete M2 nearer the top 1 of the slab, is a boundary layer L.
- the boundary layer L may be interpreted as representing the line (or zone) below which the concrete mass M1 is sufficiently consolidated, firm and dry to effect the desired concrete curing rate and properties, and immediately above which line the concrete mass M2 is not sufficiently consolidated, firm and dry to effect the desired concrete curing rate and properties.
- the boundary layer L represents a line (or zone) through the concrete mass M wherein the concrete mass at all points along the boundary layer L is of substantially similar, consolidation, firmness and dryness.
- the boundary layer L may be either a very narrow line (for example as exists after a plastic concrete mass is vibrated) or a zone having a measurable vertical width (for example as exists at the instant a concrete slab is initially poured).
- the boundary layer L which naturally occurs in a newly poured slab is notoriously uneven, as illustrated in figure 2.
- the unevenness of the boundary layer L may vary due to uneven concentrations of aggregate, or pockets of water, etc. in the poured concrete mass M.
- the curing rate (and, therefore, the strength and consistency) of the concrete mass M will normally vary depending upon the depth of the boundary layer L below the stop surface 1 of the slab. More specifically, in a given vertical segment of the concrete slab, the greater the depth below the surface 1 to the bottom of the insufficiently consolidated, insufficiently firm and insufficiently dry concrete mass M2, the longer the curing time for that particular vertical segment of the concrete slab.
- a vibrator apparatus 3 capable of introducing vibrations into the concrete mass M moves across the top surface 1 of the slab in the forward direction (indicated by arrow 4 in the figures). As the vibrator apparatus 3 is activated, it introduces vibrations into the concrete mass M beneath the vibrator apparatus, which causes water and air entrapped inside of the concrete mass M to migrate upwards towards the top surface 1 of the slab.
- the boundary layer L ahead of the vibrator apparatus 3 remains substantially unchanged (i.e. uneven and at a relatively lower elevation). It has been found that, due to internal friction within the concrete mass M as well as the geometric diffusion of the vibrational energy, the farther away from the vibrator apparatus, the less the vibrations are felt and the less the effect of the vibrator apparatus. Accordingly, the vibrations more profoundly affect the concrete mass beneath the vibrator apparatus 3 than concrete mass distant to the vibrator apparatus 3.
- the depth of the boundary layer La beneath the vibrator apparatus 3 can be correspondingly adjusted.
- Sensors 5 in communication with the vibrator apparatus 3 monitor the instantaneous depth of the boundary layer L beneath the vibrator apparatus 3.
- the sensors 5 provide feedback data to a processing unit 6 which determines the depth and profile of the boundary layer L and which adjusts the frequency of the vibration, the amplitude of the vibration, and/or the duration of the vibration (i.e. by varying the forward speed of the vibrator apparatus 3) as necessary to effect the desired profile of the boundary layer La.
- Figure 4 illustrates the condition of the concrete slab after the vibrator apparatus has completed a first pass or first "stage" of vibration of the concrete mass M.
- first stage of vibration of the concrete mass M.
- the volume of the sufficiently consolidated, sufficiently firm and sufficiently dry concrete mass M1 is greater, and the profile of the boundary layer La is more flat, after the first stage of vibration is completed (as illustrated in figure 4).
- the vibrator apparatus 3 may then be used for a second pass or "stage” of vibration, as shown in figure 5, to further raise the boundary layer Lb.
- the vibrator apparatus 3 may then be used for a second pass or "stage” of vibration, as shown in figure 5, to further raise the boundary layer Lb.
- the consolidation and drying of the concrete mass M is expedited relative to that which would naturally occur from stagnant settling of the concrete mass.
- the structural integrity of the slab is improved.
- the structural integrity of the slab is improved by use of the present invention due to the improved consistency of consolidation, (represented by the substantially horizontal orientation of the boundary layer Lb), and due to the expedited migration (and subsequent removal) of water from the concrete mass which advantageously results in less entrapped water and air pockets in the concrete slab.
- the depth of the sufficiently consolidated, sufficiently firm and sufficiently dry concrete M1 extends from the bottom of the slab 2 to (or nearly to) the finishing zone 7 at top surface of the concrete slab 1.
- the water which had migrated toward the top of the slab 1 may accumulate in the finishing zone 7, and may subsequently simply evaporate, run off the slab due to gravity, be pushed off the slab by the vibrator apparatus 3, be vacuumed, or otherwise removed.
- the boundary layer L (or more specifically the top of the sufficiently consolidated, firm and dry concrete mass M1), is evenly brought up towards the top surface of the concrete slab 1. Because the boundary layer L, (or more specifically the top of the sufficiently consolidated, firm and dry concrete mass M1, is evenly brought up towards the top surface of the concrete slab 1), the entire top of the slab 1 (or more specifically, the finishing zone 7) becomes in condition for finishing operations at substantially the same time. In the preferred embodiment of the invention, the boundary layer L is so evenly brought upwards toward the top surface of the concrete slab 1 that the depth of the boundary layer Lc does not vary by more than 1 inch after completion of the final stage of vibration.
- the present invention not only expedites the consolidation and drying of the relatively deep pockets of moist and unconsolidated concrete by applying vibrational energy directly above such areas, but it also restricts the premature drying and hardening of relatively shallow areas of moist and unconsolidated concrete by reducing the vibrational energy imparted into such shallow areas. It may be appreciated by those skilled in the art that if constant vibrational forces were equally imparted into all areas of a heterogenous concrete mass, the boundary layer would approach the surface of the slab earlier in some areas than in other areas, thus having the undesirable effect of causing "hard spots" in the concrete mass. Hard spots in concrete typically cause uneven curing, cause cracking of the slab, increase the difficulty of finishing operations, virtually precludes the use of automatic finishing equipment, and significantly reduce the structural strength of the slab.
- a concrete slab made with the method and apparatus of the present invention has fewer (or no) hard spots, is more easily finished, has fewer cracks, and is structurally more strong than concrete slabs produced using either uncontrolled vibrations or using no vibrational input.
- a vacuum water removal system may be provided comprising a vacuuming device which employs a rolling or track-like device attached to the vibrating apparatus.
- a vacuuming device preferably includes a means of imposing a vacuum within a rolling cylinder, the exterior surface of the cylinder being porous and composed of a material through which water, but not the other materials composing concrete, could freely pass.
- the exterior surface of the vacuum enclosing cylinder is kept clear of accumulated materials by a scraper which is in contact with the surface at some time during each rotation of the cylinder.
- the vacuum is applied to the porous surface only when that surface is in contact with the surface of the concrete mass.
- the surface speed of the rolling cylinder is preferably made to match the speed of the vibrator apparatus relative to the surface of the concrete mass.
- a concrete slab placed in accordance with the method and apparatus of the present invention produces a top surface 1, and finishing zone 7, of uniform physical character over the entire area of the slab. Furthermore, because of the consistency of the physical character of the entire area of the surface of the slab, finishing operations may be performed automatically by machine.
- this method and apparatus for placing concrete by staged vibration uniquely produces a uniform surface condition which allows the finishing of the top surface to be performed automatically by machine without the problems which typically hinder prior automatic finishing efforts in concrete slabs placed by prior methods and apparatuses.
- the disclosed staged vibration method and apparatus for placing concrete is effective due to the reaction of concrete to vibration.
- the water, air and certain finer and lighter materials migrate upward, with the materials' migration being affected by the characteristics of the vibration including the amplitude, frequency and duration of the vibration.
- the characteristics of the vibration are adjusted in the present invention to consolidate the relatively less consolidated, relatively less firm and relatively less dry concrete M2 near the top 1 of the slab at a controlled rate.
- the effect of the vibration is also dependent upon the shape, orientation and configuration of a surface (or surfaces) of the vibrator apparatus 3 which is in contact with the concrete mass M and which imparts the vibrations to the concrete.
- consolidation of the concrete mass M occurs in stages to bring water to the surface for removal in a manner that finishing operations, if necessary, (or curing, if no finishing operations are required), may immediately follow behind the concrete placing operations at a uniform rate.
- a concrete slab can be placed without using wire mesh (which is commonly imbedded inside of concrete slabs so as to reduce the undesirable affects of uneven drying and curing rates between the top and bottom of the slabs).
- the vibration produces an boundary layer La and Lb between the relatively consolidated and relatively unconsolidated portions of the mass M1 and M2, respectively, with the boundary layer preferably being maintained as nearly as possible at a uniform depth below the top surface 1 of the slab.
- the vibrator apparatus used in the preferred embodiment of this invention differs from prior vibrators by including a structure (i.e. sensors 5) which enables the location of the boundary layer L relative to the surface of the slab 1 to be determined with an associated feedback control system (i.e. processor unit 6). Sensors 5 may be mounted on or adjacent to the vibrator apparatus 3. The sensors 5 sense the depth of the boundary layer L, La or 5 Lb, and, through suitable feedback data processing equipment (i.e. processor unit 6), the controllable features of the vibrator apparatus 3 are adjusted as necessary to leave behind a boundary layer La and Lb at a substantially uniform depth below the top surface 1 of the slab.
- a structure i.e. sensors 5
- Sensors 5 may be mounted on or adjacent to the vibrator apparatus 3.
- the sensors 5 sense the depth of the boundary layer L, La or 5 Lb, and, through suitable feedback data processing equipment (i.e. processor unit 6), the controllable features of the vibrator apparatus 3 are adjusted as necessary to leave behind a boundary layer La and Lb at a substantially
- the sensors 5 may be advantageously positioned to determine the vertical location of the boundary layer L, La and Lb at locations in front of, behind or directly beneath the vibrator.
- the sensors 5 are preferably mounted in a manner such that the vibrations will not adversely affect performance of the sensors 5. Further, the sensors 5 are preferably provided in sufficient numbers and at sufficient locations to sense the location of the boundary layer L at as many sites relative to the vibrator apparatus 3 as may be necessary to produce the desired location and profile of the boundary layer La and Lb.
- the characteristics of the vibrator apparatus 3 which are controlled include the frequency, amplitude and focus or direction of vibrating energy. In addition the forward speed of the entire vibrator apparatus 3 may be controlled.
- the vibrator apparatus 3 may comprise means for adjusting the character of the vibrations to enable vibrations to be focused to a particular depth either by independent adjustment of individual vibrators or by adjustment of a plurality of vibrators in concert with each other, thus providing additional control of the depth of the consolidation of the concrete by the vibrator apparatus.
- a plate vibrator 3a (as shown in figure 7) having either one or a plurality of moving pistons or rotating eccentric vibrators 8 mounted thereon, with each vibrator 8 being individually controlled by its own sensor Sa and processor unit 6a (or by a single multifunctional processor unit, not shown) which reads the conditions in front of the plate 9.
- sensor Sa and processor unit 6a or by a single multifunctional processor unit, not shown
- Additional sensors 5b may be mounted behind the plate vibrator 3a in order to sense the results of the vibration.
- the plate vibrator 3a can be pulled or moved by a winch which moves at a speed that is also controlled by the sensor's (5) data.
- the sensor 5 may rely on mechanical probes, submerged sleds or skis, or acoustic characteristics, penetrating radar or similar technology for determining the depth of the boundary layer. Typically, mechanical sensors are less expensive than more sophisticated probes.
- Several alternative arrangements are suitable for supporting the vibrator apparatus above or on the top surface of the concrete slab 1, including, but not limited to the following: support from 5 concrete forms; support from support arms mounted upon various types of peripheral equipment; support from skis riding on tracks; support from skis or sleds submerged in the concrete mass and riding on the boundary layer L between the top and bottom concrete portions M2 and M1, respectively; or the vibrator apparatus 3 may be supported by any means which will allow the vibrator apparatus 3 to move in a manner to produce the desired staged vibration.
- a piston 11 is pivotally connected to a pivot arm 12, with the bottom of the pivot arm being provided with a flat plate 13 which comprises the sensing surface of the probe Sc.
- the flat plate 13 determines the location of the boundary layer L between the relatively more consolidated, relatively more firm and relatively drier concrete M1 near the bottom 2 of the slab and relatively less consolidated, relatively less firm and relatively less dry concrete M2 near the top 1 of the slab.
- the force required to push the flat plate 13 downward to the location of the boundary layer L is measured.
- Calibration of the force indicative of the boundary layer L may preferably be based on a determination of the force required to push against a sufficiently consolidated, sufficiently firm and sufficiently dry concrete mass, and this data preferably forms the basis of the feedback control system.
- An alternative sensor which may be used with the present invention is a sled probe 5d, as illustrated in figure 9.
- the sled 14 is mounted on a pivoting support arm 15 extending from the beam 16.
- the sled has a substantially flat bottom surface 14a that is dragged along by the forward moving beam 16. The force required to keep the sled 14 at the correct penetration into the boundary layer L is determined and forms the reference point for the feedback control system.
- the present invention provides a method and apparatus for placing concrete slabs which eliminates the need for various additives (such as drying agents, accelerators, plasticizers, etc); which results in more uniform slab density; which has a flatter finished surface, less shrinkage, less curling and fewer cracks; and which requires the use of less manpower, than is typically necessary with prior concrete placing methods and apparatuses.
- This disclosed method and apparatus for placing concrete slabs can be used in conjunction with common form systems or laser screeding.
- the vibrating apparatus 3 may ride on reinforcing bars, on an independent base, on metal forms (as illustrated in figure 10), or other supporting means.
- FIG 11 illustrates a modified vibrator apparatus 3b which is capable of applying vibrations directly to the concrete mass M beneath the surface 1 of the concrete slab.
- the modified vibrator apparatus 3b is provided with wheels 18 which ride upon rail(s) 19.
- a vibrating arm 20 is pivotally connected to an eccentric drive motor 21 on one end, and attached to a tamping rod 22 which extends below the surface 1 of the concrete slab at its opposite end.
- a substantially horizontally oriented vibrating plate 23 is attached to the bottom of the tamping rod 22.
- the final finished concrete surface of the slab - is related dimensionally to a reference device or system.
- a reference system may comprise either the fixed rails (such as rails 19 in figure 11) or fixed forms (such as metal form 17 in figure 10), or a laser system in fixed relationship to the sub-base B (not shown), or similar means.
- a modified vibrating apparatus 3c is illustrated in figure 12.
- the vibrating apparatus 3c shown in figure 12 comprises a flexible structure 30 which moves vertically and/or horizontally relative to the surface upon which it rests, the structure typically being supported by wheels 81 which roll upon the sub-base B, or by skids (not shown) which rest upon the structural steel or formwork 31 of the installation.
- the vertical locations of the sensors 5 and the vibrating surface 32 (or surfaces) relative to the structure 30 are preferably fixed.
- the entire structure 30 adjusts vertically in response to data supplied to the processor unit 6 by an optical sensor 40 or other instrument which detects the vertical location of the reference device or system relative (for example the formwork 31) to the structure 30, maintaining a predetermined vertical relationship with that device or system.
- the processor unit 6 receives data from the sensors 5 regarding the elevation of the boundary layer L, as well as data pertaining to the relative elevation of the reference device (i.e. formwork 31) from the optical sensor 40, and adjusts the vibrating characteristics of the vibrating apparatus 3c, the forward speed of the structure 30 and the relative locations of the vibrating surface(s) 32 so as to produce a boundary layer L which is as nearly parallel to the desired surface 1 of the concrete slab as possible.
- the second concrete pour is preferably made after initial series of staged vibrations have been introduced to the first-poured concrete in accordance with the present invention, but before the boundary layer reaches too close to the top of the first-poured concrete mass.
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Abstract
Description
Claims (9)
- A method of placing concrete comprising the following steps:depositing a plastic concrete mass to form a concrete structure (M), said concrete structure having a bottom surface (B) and a substantially flat top surface (1);introducing into said concrete structure a first series of vibrations so as to cause a first segment of said plastic concrete mass (M1) to become relatively more dense than a second segment of said plastic concrete mass (M2), said first segment (M1) extending from said bottom surface of said concrete structure (B) to a manipulatable definable boundary layer (L), said second segment (M2) extending from said manipulatable definable boundary layer (L) to said top surface of said concrete structure (1), wherein said first series of vibrations causes said manipulatable definable boundary layer to become located at a first position (La) between said first segment (M1) and said second segment (M2);determining the location of said first position of said manipulatable definable boundary layer (La);introducing into said concrete structure a second series of vibrations subsequent to said first series of vibrations so as to cause said manipulatable definable boundary layer to become located at a second position (Lb) closer to the top surface (1) than said first position (La);and controlling a physical characteristic of said second series of vibrations so as to cause said manipulatable definable boundary layer to be more closely parallel to said top surface of said concrete structure (1) at said second position (Lb) than at said first position (La).
- A method according to claim 1, wherein said step of introducing said first series of vibrations into said concrete structure comprises the steps of vibrating a first tamping member (9) disposed in contact with said plastic concrete mass (M) and above said manipulatable definable boundary layer (L); and moving said first tamping member (9) along said concrete structure during vibration of said concrete structure.
- A method according to claim 2, wherein said steps of determining the location of said first position of said manipulatable definable boundary layer (La) and of adjusting said physical characteristic of said second series of vibrations are each performed concurrently with said step of moving said first tamping member (9).
- A method according to claim 2 or 3, comprising the step of immersing at least a portion of said first tamping member within said second segment of said plastic concrete mass (M2).
- A method according to any preceding claim, wherein the step of determining the location of said first position (La) of said manipulatable definable boundary layer comprises generating feedback data; and said step of controlling a physical characteristic of said second series of vibrations comprises the steps of processing said feedback data and adjusting said physical characteristic of said second series of vibrations in response to said feedback data.
- A method according to any preceding claim, wherein said controlled physical characteristic of said second series of vibrations comprises frequency, amplitude or duration.
- Apparatus for placing a plastic concrete mass for forming a concrete structure (M) having a bottom surface (B), a substantially flat top surface (1) and an area within a definable perimeter, said apparatus comprising:a tamping member (9) operative to vibrate at a first frequency and at a first amplitude for introducing into said concrete structure a first series of vibrations so as to cause a first segment of said plastic concrete mass (M1) to become relatively more dense than a second segment of said plastic concrete mass (M2), said first segment (M1) extending from said bottom surface of said concrete structure (B) to a manipulatable definable boundary layer (L), said second segment (M2) extending from said manipulatable definable boundary layer (L) to said top surface of said concrete structure (1), wherein said first series of vibrations is adapted to cause said manipulatable definable boundary layer to become located at a first elevation (La) such that said first segment (M1) is below said first elevation (La) and said second segment (M2) is above said first position (La);said tamping member (9) being operative to vibrate at a second frequency or at a second amplitude for introducing into said concrete structure a second series of vibrations subsequent to said first series of vibrations so as to cause said manipulatable definable boundary layer to become located at a second elevation (Lb) closer to said top surface than said first elevation (La);a sensor (5) for determining the location of said first elevation of said manipulatable definable boundary layer (La);and processor means (6) coupled to said sensor (5) and said tamping member (9) for controlling the frequency, the amplitude or the duration of said second series of vibrations.
- Apparatus according to claim 7, comprising moving means (10) for moving said tamping member (9) along said concrete structure during vibration of said concrete structure.
- Apparatus according to claim 8, wherein said processor means (6) is adapted to process signals from said sensor during movement of said tamping member and to adjust said first amplitude or said first frequency to said second amplitude or said second frequency, respectively, in response to said sensor signals.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US5500493A | 1993-04-30 | 1993-04-30 | |
US55004 | 1993-04-30 | ||
PCT/GB1994/000859 WO1994025681A1 (en) | 1993-04-30 | 1994-04-22 | Method and apparatus for staged vibration of concrete |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0698153A1 EP0698153A1 (en) | 1996-02-28 |
EP0698153B1 true EP0698153B1 (en) | 1998-06-24 |
Family
ID=21994947
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94913683A Expired - Lifetime EP0698153B1 (en) | 1993-04-30 | 1994-04-22 | Method and apparatus for staged vibration of concrete |
Country Status (10)
Country | Link |
---|---|
EP (1) | EP0698153B1 (en) |
JP (1) | JPH08510302A (en) |
KR (1) | KR960702033A (en) |
CN (1) | CN1052281C (en) |
AT (1) | ATE167716T1 (en) |
CA (1) | CA2161454A1 (en) |
DE (1) | DE69411269T2 (en) |
DK (1) | DK0698153T3 (en) |
ES (1) | ES2117271T3 (en) |
WO (1) | WO1994025681A1 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10025561A1 (en) | 2000-05-24 | 2001-12-06 | Siemens Ag | Self-sufficient high-frequency transmitter |
CN101550764B (en) * | 2008-04-06 | 2012-12-05 | 孙长顺 | Concrete pouring machine |
CN103195254B (en) * | 2013-02-21 | 2015-11-04 | 中国电建集团成都勘测设计研究院有限公司 | Concreting is vibrated base layer automatic monitoring method |
CN103433998B (en) * | 2013-07-18 | 2016-09-28 | 浙江中隧桥波形钢腹板有限公司 | A kind of concrete frequency and amplitude simultaneous change vibration method |
CN103862552B (en) * | 2014-03-31 | 2016-05-11 | 湖南三一快而居住宅工业有限公司 | Precast concrete production system and vibrating device thereof, vibration control method |
CN105569345B (en) * | 2015-12-09 | 2018-10-02 | 重庆飞强混凝土有限公司 | Concrete branch densification process |
JP6919937B1 (en) * | 2020-05-14 | 2021-08-18 | エクセン株式会社 | Concrete vibrator |
CN114571576B (en) * | 2022-03-25 | 2023-07-21 | 浙江寰龙环境科技有限公司 | Solid waste preparation haydite production line |
CN117536363B (en) * | 2024-01-10 | 2024-03-26 | 内蒙古电力(集团)有限责任公司内蒙古电力经济技术研究院分公司 | Energy-saving heat-preserving building wall structure and construction method thereof |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1097651A (en) * | 1965-09-03 | 1968-01-03 | Stothert & Pitt Ltd | Improvements in vibratory compactors |
US3555983A (en) * | 1968-08-02 | 1971-01-19 | Cmi Corp | Paving grout control device |
US4128359A (en) * | 1977-11-14 | 1978-12-05 | Cooper Jr Charles R | Self-propelled concrete vibrator apparatus |
DE3509725A1 (en) * | 1985-03-18 | 1986-09-18 | Heilit + Woerner Bau-AG, 8000 München | METHOD FOR LAYING ROAD CEILINGS KEYWORD: RUETTEL RESTRICTION IN THE DOWEL AREA |
-
1994
- 1994-04-22 JP JP6523999A patent/JPH08510302A/en active Pending
- 1994-04-22 DE DE69411269T patent/DE69411269T2/en not_active Expired - Fee Related
- 1994-04-22 ES ES94913683T patent/ES2117271T3/en not_active Expired - Lifetime
- 1994-04-22 EP EP94913683A patent/EP0698153B1/en not_active Expired - Lifetime
- 1994-04-22 WO PCT/GB1994/000859 patent/WO1994025681A1/en active IP Right Grant
- 1994-04-22 AT AT94913683T patent/ATE167716T1/en not_active IP Right Cessation
- 1994-04-22 DK DK94913683T patent/DK0698153T3/en active
- 1994-04-22 KR KR1019950704769A patent/KR960702033A/en active IP Right Grant
- 1994-04-22 CA CA002161454A patent/CA2161454A1/en not_active Abandoned
-
1995
- 1995-04-22 CN CN94192365A patent/CN1052281C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
CA2161454A1 (en) | 1994-11-10 |
DE69411269D1 (en) | 1998-07-30 |
KR960702033A (en) | 1996-03-28 |
DE69411269T2 (en) | 1999-02-18 |
DK0698153T3 (en) | 1999-04-06 |
ES2117271T3 (en) | 1998-08-01 |
CN1124989A (en) | 1996-06-19 |
CN1052281C (en) | 2000-05-10 |
EP0698153A1 (en) | 1996-02-28 |
WO1994025681A1 (en) | 1994-11-10 |
ATE167716T1 (en) | 1998-07-15 |
JPH08510302A (en) | 1996-10-29 |
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