US3861201A - Method and apparatus for early strength testing of in-place concrete - Google Patents

Method and apparatus for early strength testing of in-place concrete Download PDF

Info

Publication number
US3861201A
US3861201A US368325A US36832573A US3861201A US 3861201 A US3861201 A US 3861201A US 368325 A US368325 A US 368325A US 36832573 A US36832573 A US 36832573A US 3861201 A US3861201 A US 3861201A
Authority
US
United States
Prior art keywords
disk
test
formwork
counterholder
strength
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
Application number
US368325A
Other languages
English (en)
Inventor
Franz Kaindl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RICHARDS OWEN
Original Assignee
Richards Owen
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Richards Owen filed Critical Richards Owen
Application granted granted Critical
Publication of US3861201A publication Critical patent/US3861201A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/38—Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
    • G01N33/383—Concrete or cement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0092—Visco-elasticity, solidification, curing, cross-linking degree, vulcanisation or strength properties of semi-solid materials

Definitions

  • ABSTRACT Reduced scatter in strength determinations of hardening inhomogenous materials such as concrete is achieved by in-place screen-rejection of coarseparticle ingredients from test bodies evaluated by variations of the tensile-shear or pull-out method.
  • Nonor semi-destructive tests on specimens or structures at any age are described in connection with construction safety, structural load-bearing capacity, evaluation of materials and systems.
  • Use of flexible filler in the pullout ring extends the applicability of the test system into the interior of mass structures.
  • Portable apparatus requires no utility services.
  • This invention has two goals:
  • Strength determined by this method is a measure of in-place strength of the material tested, such as concrete. The strength number reported is directly related to structural strength, the strength of the building element in use, and so to rational definition of safety and cost risks.
  • Prior art strength testing of concrete is dominated by the 6 X 12 inch cylinder specimen, tested in the laboratory after curing for 28 days at ideal conditions of 90+% relative humidity and 73.4:3F.
  • the strength number reported is a potential strength used to establish acceptability of ingredient materials such as cement, aggregate and chemical admixtures; it is not a measure of in-place safety or cost.
  • Prior art variations of the potential strength cylinder test include subjecting that standard cylinder to curing similar to that of field structures and to tensile strength tests of artificially cured specimens. Other variations include curingthe cylinder in the field under various elaborately described conditions, which are generally recognized as resulting in strength numbers variably higher than in-place actuality.
  • This inventions emphasis on pull-out or push-in tests involves measuring force to rupture within the concrete about a conic frustum of surface defined by a forcing ring and a coaxial piston ram.
  • Concrete tested by this invention may be in portable specimens tested. under the same curing conditions as the potential strength specimens.- If this is done, results of the two testswill correlate very closely.
  • An example is the work done at the'Bureau of Reclamation of the U.S. Dept. of the Interior in Denver, Colorado in 1972-73: coefficients of correlation were 0.97* for cast slabs and 0.87 for shotcrete panels.
  • Another example is the Feb., 1972' program of the National Sand and Gravel Association National Ready Mixed Concrete Association at their laboratory at the University of Maryland; results of tests of three mixes are plotted:
  • Aggregate size also has an important effect on scatter of reported strength results, as long and widely recognized in the industry.
  • the inventors in previous patents and statements, have reported this also applies specifically to pull-out tests, as have B. G. Skramtajew (AC1 Journal Title 34-15, Jan-Feb. I938); P. Kierkegaard- Hansen (U.S. Pat. No. 3,541,845) and his Technical University of Denmark colleague, H. Krenchel; T. P. Tassios, National Technical University of Athens Report 21, 1968; and others. Similar effects apply to other strength and quality tests, such as drilled cores, flexural and tensile specimens, impact (Swiss Hammer) tests, indentation (Windsor Probe, l-lilti) and other tests.
  • screening reduces the total air content and increases the net air content in the screened undersize fraction. If true, and provable, the higher air-content of the undersize fraction should reduce its reported strength, thus tending the opposite way to the higher reported strength expectable (according to some) from test of a smaller diameter cylinder.
  • a truly non-destructive tensile-shear test demonstrates in-place strength in excess of a required minimum when specified force is maintained for a given time, say 20 seconds, without failure. Even in cases when incipient rupture has taken place, immediate release of load has made it possible to retest at later ages and (due to autogenous healing) demonstrate strengths comparable companion units not theretofore tested.
  • apex angles of perhaps 90-120 (360 defining a circle).
  • Tremper Woodgrass
  • a typical configuration might be of the following dimensions: loading piston head diameter of 30 millimetres (mm) (approx. 1.18 in.); counterforce ring inside diameter of mm (2.76 in.); and conic frustum height spacing between those two concentric and parallel members of 30 mm. This arrangement would have an apex angle of about 67.4, based on tan a/2 (7-3)/2 X 3 2/3.
  • a variation of this invention is to mount such an inplace screen apparatus, perforated plate, grizzly-bar or similar obstruction in the line of delivery or forming of plastic material, such as concrete, in a construction body.
  • the screen-passing fraction may then be molded and tested at that location or elsewhere, as desired.
  • the advantage of this variation is the requirement of no special equipment. Locations involved include chute and form openings or other accessable points.
  • Another form of the invention is locating screens in the intended area of test, so only undersize particles can penetrate into the immediate volume to be tested.
  • the advantage of this method is the lack of disruption to normal placing routine; the volume to be tested is filled automatically.
  • a further variation is detachable fastening of screens to forms, giving the advantage of simple disposition of oversize. Tests are possible through formwork openings or after form removal. As the screen itself is embedded in concrete, screen-to-form fastenings must be disconnected before testing.
  • Another variation is combining screens and tests hardware on form openings before concrete placement.
  • the advantage of the combination reusable plate optional screen/test units package is that test and test time decisions can be made even after completion of formwork erection. Where all formwork members are so equipped, testing points are discretionary, as a pull-out ring or test apparatus may be brought to any point.
  • Another variation is mounting of specific quality test hardware, such as piston insert and counterforce ring, fixed on plate in frustum-defining orientation.
  • the piston is movable towards the ring to cause rupture. This offers the advantage that immediately upon mass set or hardening, one already knows the frustum area; the force and strength and determinable at once.
  • Another version of the invention is to emplace, or allow for future emplacement, of quality test hardware, such as piston and ring, on a combination reusable plate with or without a screen.
  • This step has the advantage that if aggregate rejection apparatus is not required at a particular stage, or if it is desired to investigate correlation/aggregate size/number of tests parameters, one may save the cost of a screen apparatus.
  • Another variation is to use such a plate, suited for filling of a form opening or for substitution of a section of a form, for the mounting or fastening in-place of test hardware, such as ring or piston, by means of platehardware detachable fastenings, thus achieving time savings.
  • a further form of the invention is to attach, by a detachable device, to such a plate a pull-out or push-in shaft guide tube, to which in turn such hardware may be detachably held in place during concrete placement, in addition to such hardware being optionally detachably fastened to reinforcing steel or other rigid objects in the concrete placement space, thus facilitating optional non-use of screen.
  • the ring is positioned nearer the future concrete surface than the piston and the piston is moved towards the ring.
  • Another version of the invention is to position the piston closer to the future concrete surface than the ring and to force the piston towards the ring. This is advantageous as this configuration requires no piston shaft, since the force-originating apparatus may act di rectly against the piston. It also makes unnecessary a buckling-resistant shaft.
  • Another version is to fill the ring opening with an easily collapsable dummy which will yield to intrusive movement of the ruptured test frustum.
  • the advantage of this is that it makes possible tensile-shear tests in the interior of concrete.
  • a further form of this invention provides for the direction of movement of the piston towards the ring, when generally parallel to the future concrete surface, to be inclined with that direction towards the inside of the test mass.
  • the advantage of this step is to inhibit outward premature spalling of the test mass and variable results.
  • a further form of the invention is for the test force, acting generally parallel to the mass surface, to be transmitted by a device acting roughly parallel to the mass surface; this device is pressed against the test mass by a guided roller arrangement.
  • the advantage is inhibiting premature outward spalling.
  • a further form of the invention is to attach, either permanently or detachably, test hardware such as piston and ring to forming or to a portable form section which may be detachably fastened in form openings.
  • test hardware such as piston and ring
  • a portable form section which may be detachably fastened in form openings.
  • the advantage of this step is simple mounting of test apparatus. If hardware is to be installed at some depth inside the mass under test, that hardware must be held firmly in the desired position during attrition of construction and concrete placement.
  • Such hardware may include one or more of the following: screens, piston shafts, rings, piston shaft guide tubes, form-closing fasteners, access or inspection doors and other devices of use in execution of the method. Access doors may be used for the purpose of obtaining sample quantities of material or, after concrete hardening, conducting impact-rebound, indentation or other tests on the concrete surface.
  • Another version of the invention is to provide dummy displacement elements on the inside of forms, reusable plates or portable form sections for the purpose of creating recesses into which can be inserted test hardware.
  • Such hardware may include ring. piston. and hydraulic load cell for exertion of test force generally parallel to the concrete surface.
  • the advantage of this step is the inside application of test force, the direction of which can be accurately controlled. and avoidance of outward spalling.
  • Apparatus covered by this invention includes a screen grid, the outer rods of which are parallel or at an acute angle to the placing direction of the concrete. thus facilitating deflection and rejecting coarse aggregate particles and inhibiting blocking or blinding screen openings.
  • Another embodiment of the invention is a screen detachably fastened to a plate (measuring plate). which can be detachably fastened in formwork openings.
  • the advantages of this are high rigidity of plate and screen, which have to withstand high attrition and loading during concrete placement.
  • the plate may be detached from screen and form opening and reused elsewhere.
  • Another embodiment of apparatus is the measuring plate equipped with detachable closing discs or doors over openings through which the concrete inside can be sampled or tested.
  • the advantage of this feature is that one may have access to the formwork interior without removal of the entire measuring plate and conduct tasks such as inserting pull-out shafts to pistons or carrying out impact-rebound tests.
  • Another embodiment connects the screen directly to the counterforce ring. This offers the advantage of sim ple, rigid design and minimum test specimen size and screen loading.
  • Another embodiment of invented apparatus provides for inclusion, in the counterforce ring opening, of an easily collapsable filler or resiliant disk, which will accomodate movement of the base of the frustum ruptured during the tensile-shear test.
  • the advantage of this feature is to facilitate this test when the ring is not outside the concrete surface.
  • a further embodiment is a protecting disk covering the far side of ring and resilient filler.
  • the advantage of this step is to insure that the concrete, during placement, does not prematurely indent or depress the rings resilient disk, the full volume of which should be ready to receive displacement of the moving frustum.
  • a further embodiment of apparatus is a guide tube, extending from the future test mass surface almost to the piston, said guide tube housing the test force transmission shaft.
  • the advantage of this device is that the guide tube, preferably made of synthetic material, inhibits the shaft-test mass bond and facilitates lowvariation test results of tensile-shear strength.
  • a further embodiment of apparatus is rigid connection between protecting disk and guide tube. The advantage of this is added strength of assembly.
  • Another embodiment of invented apparatus is an oblong hole in piston, a hole of such dimensions that an especially shaped pull-out rod can be inserted and coupled to the piston.
  • the advantage of this is that the rod, which can be relatively expensive for greater depths of embedment, can be withdrawn after strength determination and reused.
  • Another embodiment of apparatuss is a force shaft extending from the piston to near the test mass surface
  • FIG. 1 is an elevation end view of a screen assembly embodiment of the invention as mounted on framework to keep course aggregate out of a designated test area;
  • FIG. 2 is a perspective schematic view of a screen assembly
  • FIGS. 3 to 8 are elevation views, partly in section of a screen assembly in place in a concrete body showing various test fixture configurations
  • FIG. 9 shows a loading disc with interlocking pull rod structure in end and side view
  • FIG. 10 is an elevation view, partly in section of a test fixture arrangement in a concrete body together with a partial end view;
  • FIG. 11 is an elevation view, partly in section of a further test fixture arrangement in a concrete body
  • FIG. 12 is a side view, partly in section and end view of a loading disk with interlocking rod structure
  • FIG. 13 is an elevation view, partly in section of a further screen assembly embodiment of the invention and adjacent formwork;
  • FIG. 14 is an elevation view, partly in section of a force rod decoupling embodiment.
  • FIGS. 15a and 15b are respectively an elevation view segment, partly in section, and top view segment of the relationships of the screen assembly, test disks and formwork of an embodiment of the invention.
  • l designates the inner and 2 the outer screen rods, 3 the screen mesh aperture, 4 the formwork to which the screen is screwed with screws 5 and cross ties 6, and 7 the placing direction.
  • FIG. 2 shows a schematic view of the screen where for the sake of better comprehensibility the back lateral grid is omitted.
  • the outer grid rods are drawn in full lines and the inner ones in dashed lines.
  • the outer screen rods which are arranged parallel or in an acute angle in relation to the placing direction so that the inflow of the finer grain into the measuring space is not hindered by the coarser component. If the rods of the screen, which are perpendicular to this direction, were on the outside, they would adversely affect the flow of the coarser grain along the rods so that the inflow of the finer grain would be hampered.
  • FIG. 3 shows a screen in which the counterholder ring (11) borders the measuring space, and where the loading disk (10) is arranged on the surface (17) of the placed mass (14), and is loaded by a hydraulic pressure cylinder (20) with its piston (22) in the direction of the counterholder ring (11).
  • the load applied to the loading disk (10) is continually increased until the bond between the frustum shell (16) [defined by the loading disk circumference and the opening of the counter-holding ring (11)]and the surrounding screened mass (50) is broken so that the basis of the frustum sinks into the resilient disk (displacement disk) (12).
  • the resiliency of the latter must not be so high that it is essentially compressed as early as the fine grain enters the measuring space. Because in this case the frustum basis would not be able to sink in during the measurement. As a consequence there would not result a load relief of the frustum and a pressure relief in the pressure cylinder, which however is required to show on the pressure gauge (18) that the bond on the frustum shell (16) is broken.
  • the hydraulic cylinder would be operated later without the possibility of determining the material strength. Therefore, the resiliency of the replacement disk (12) must have an upper limit defined by the maximum pressure of the fresh concrete inside the measuring space and a lower limit defined by the lowest concrete strength to be measured.
  • the quotient of the measuring value indicated by the drag pointer of the pressure gauge (18) and the frustum shell (16) area results in the so-called tensional shear strength which follows approximately the direct relation to the bending strength and the compression strength: 1 l 4, as extensive experimentation has shown.
  • the area of the frustum shell is defined by the diameter of the loading disk (10) and the diameter of the opening of the counterholder ring (11) and by the distance (23) between disk (10) and ring (11). If these dimensions are kept constant in all measuring points then the pressure gauge can be calibrated in concrete strength values so that its drag pointer directly indicates the respective momentary concrete strength (B) in kp/cm when it comes to a standstill in the moment in which the bond on the frustum shell breaks.
  • Such a concrete strength scale is based on the below approximate formula in which (P) designates the effort (in kp) on the loading disk required for breaking the bond on the frustum shell and (M) the frustum shell area (in cm).
  • the value of the load P is the product of the value of pressure (in kp/cm at the pressure gauge (18) at the standstill of the drag pointer and the effective crosssection area of the piston inside the hydraulic pressure cylinder (20).
  • An additional scale on the pressure guage (18) for reading the pressure (P) (in kp) exerted by the hydraulic cylinder on the loading disk (10) is useful for measurements in which for some reason the value of the frustum shell area or of the distance (23) between loading disk and counterholder ring can not be kept constant.
  • FIG. 3 does not show the fixing of the screen.
  • the screen (1,2) can be fixed on the reinforcing shell in such a way that its upper side flush with the future concrete surface (17).
  • the upper transverse screen rods (1) are screwed to the formwork or the ends of the outer rods (2) are bent parallel to the formwork and screwed to it.
  • FIG. 4 shows a version similar to that of FIG. 3 but wherein the loading disk (10) flush with the concrete surface (17).
  • the disk (10) In the case of the presence of a formwork the disk (10) is screwed to it and after the placing the screw is removed. In the case of the absence of a formwork this disk is slightly clamped to a support, e.g., between two rods, 23 welded to the screen.
  • FIG. 5 shows an embodiment of the invention for measuring the strength in greater depths of the placing space (14) with the same frustum dimensions.
  • the loading disk (10) is fixed to a pressure rod (24) protected against sticking to the setting concrete by a guide tube (25) of steel or of synthetics, maintained in position by the bent ends (26) of the outer screen rods (2).
  • Greater depths of the screen in the placing space require additional stiffening means, preferably arranged inside the screen so that they do not interfere with the deviationof the coarser grain from the screen.
  • FIG. 6 shows another embodiment of the invention for measuring the strength in the depth, and where the measuring space is much smaller as compared with that of FIG. 5.
  • the screen unit Owing to the smaller size of the screen, particularly transverse to the placing direction, the screen unit is less loaded during the placing.
  • the screen rods (1,2) are welded to the counterholder ring (11) as well to the flange (27) of the guide tube (28), which in cludes a further flange (29) for fixing the unit. When it has to be arranged in greater depths it must be anchored additionally on anchor rods.
  • the figure shows a version according to which the loading disk is slightly clamped between two rods (123) welded to the screen and where the pressure rod (30) is not inserted until immediately before the measurement and can be unrestrictedly reused.
  • This rod must be dimensioned against buckling as well, considering the maximum effort on the loading disk to be transferred.
  • FIG. 7 shows a version in which an increasing effort by a hydraulic pull cylinder is transmitted to the loading disk (10) over a pull rod (37).
  • the pull cylinder would prop against the counterholder ring (11).
  • the loading disk (10) has a central bore into which the pull rod (37) is inserted which has a thickening (32) on this end.
  • the former is provided (according to FIG. 12) with such a thickening on its other end too, and the loading disk receives a further larger eccentric bore (1).
  • the rod shaft (60) is inserted laterally into the smaller central bore (62) which opens towards the eccentric larger bores (61).
  • the rod shaft is secured against lateral escaping from the small bore into thelarger one by a glue paste.
  • the counterholder ring 11 can be arranged under the future concrete surface or direct on the formwork (63) according to FIG. 12.
  • a resilient disk (13) according to the FIG. 8 is required in order to allow the sinking of the frustum basis into the opening of the counterholder ring (11).
  • the version shown in FIG. 8 serves for measuring the strength in practically unlimited depths of the placing space.
  • the screen (1,2) is welded to the counterholder ring (11) the opening of which is protected against the inflow of general unscreened mass by a protecting disk (13) welded to the guide tube (33) for the pull rod (34).
  • the guide tube (33) does not completely reach as far as the loading disk (10), where a sleeve (35) of resilient material is slipped over the tube end preventing the placed material to enter the guide tube but on the other hand allowing a small movement of the loading disk (10) when on account of a pull out force on its bond of the material along the frustum shell breaks.
  • the loading disk (10) is slightly clamped between two rods (123) welded to the screen (1,2).
  • the end of the pull rod (34) inside the measuring space has a crosspiece (36) which is inserted into the oblong hole (37) of the loading disk (10) according to FIG. 9, and the pull rod is interlocked with the loading disk by its being turned by app. 90. Therefore, the pull rod (34) can be reused for other measurements after its being unlocked and after its withdrawal out of the guide tube (33).
  • the pull rod On its outside end, the pull rod has a coupling or a thickening to which the piston of a hydraulic pull cylinder can be coupled, which props against the flange (38) of the guide tube (33).
  • FIG. 10 shows an embodiment ofthe invention where the loading disk (10) and the counterholder ring half (11) are slightly inclined towards the normal to the concrete surface (17) in such a direction that this counteracts the outside evasion tendency of the frustum half when the pull rod (40) is pulled towards the counterholder.
  • the guide rollers (41) hold the pull rod (40) against the concrete surface (17).
  • FIG. 11 shows an embodiment of the invention similar to the FIG. 10. But here an additional plate (42) is arranged in the future placing space and the entrance of mass into the space between the loading disk (10) and this plate is prevented by a dummy element of the same shape as a hydraulic pressure cylinder (43) which, for the measurement, replaces the dummy element and the piston (44) of which acts on the loading disk (10).
  • a dummy element of the same shape as a hydraulic pressure cylinder (43) which, for the measurement, replaces the dummy element and the piston (44) of which acts on the loading disk (10).
  • the loading disk and the counterholder ring half are slightly inclined as regards the normal to the concrete surface.
  • FIG. 14 shows a coupling for the force transmission rod (69) which reaches from the loading disk as far as near the mass surface (17) only, and is provided with an inner screw hole (66).
  • a cap of plastic material (65) prevents the concrete and dust to enter this screw hole, and is put on the end of the guide tube so that it also prevents material to enter the space between it and the rod (69).
  • the piston rod (68) of a hydraulic cylinder this rod has a screw bolt (67) with which the cap (65) can be perforated so that the screw bolt can be screwed into the screw hole (66). If the rod (69) is not provided for being withdrawn after measurement this solution avoids expenses for cutting protruding rod parts.
  • the FIG. 15 shows an example of a measuring plate (72) for arranging a number of pull rods (71) with loading disks (10) in openings (80) of the plate, which is mounted in an opening of the formwork (63).
  • the measuring plate is provided with mounting straps (73) which exert a pressure on a pressure frame (74) and an underlying rubber sealing (83), when the measuring plate is screwed to the formwork with the aid of the screw bolts (75), which are welded to the formwork. Therewith a tight connection between formwork and measuring plate is secured.
  • a screen (1,2) is mounted to the measuring plate (72) with the aid of the screw bolts (76) and can be unscrewed from the measuring plate for removing the latter after the concrete has hardened.
  • the measuring plate (72) wears a fixing metal strap (77), to which the pull rods (71 for the loading disks 10) are clamped with the aid of fixing screws (78) and fixing rings (79). The latter are welded to the fixing strap (77).
  • the measuring plate (72) has openings (80), which are sealed by rubber disks (81 which are pressed down by metal disks (82).
  • the fixing screws (78) are loosened and a hydraulic pull cylinder propping against the measuring plate exerts an effort over the pull rod (71) on the loading disk (10) until the frustum shell (84) loses its bond with the surrounding mass, so that the frustum basis sinks a little into the rubber plate (81).
  • the counterholder is materialized by the border of the opening (80) of the measuring plate.
  • the depth of the screen is adjusted by aspacing tube (85).
  • the measuring plate can be provided with other openings for strength measurements with the rebound hammer and with closing disks for its openings.
  • the embodiments shown in the figures demonstrate the application of the method of filtering out the coarser grain to the method of breaking the bond between the shell of the concrete frustum and the surrounding mass. But this filtering method can also be favourably applied to other strength testing methods, e.g., to the various kinds of test hammers (rebound and impression method.) and to the drill core method, i.e., to methods which can not be used until higher strength values have been reached.
  • the retaining of the coarser grain component from the measuring space especially reduces the dispersion of the measuring values of these methods, and the results are always on the safe side, as extensive investigations have shown.
  • the method of testing the strength of a body comprising a setting substance, such as concrete, having a separable component such as a coarse grain aggregate affecting the accuracy of said testing, comprising the steps of, selecting in said body a test site portion, eliminating said separable component from the test site, and testing the strength of said body located within said test site.
  • step of eliminating said component comprises the step of placing screens for shielding the test site to pass only finer grain components thereinto.
  • testing comprises the steps of mounting at the test site a disk and a counterholder with an opening larger than the disk therein spaced substantially parallel to each other, and exerting an increasing force between the disk and counterholder to break the bond between the test site and surrounding body to form thereby a truncated cone.
  • the method defined in claim 6 including the steps of placing formwork to define said body, attaching said disk and counterholder to said formwork prior to forming said body, and removing said disk and counterholder from said formwork prior to removing said formwork from said body.
  • a testing device for testing the strength of a body comprising a setting substance, such as concrete, having a separable component, such as a coarse grain aggregate affecting the accuracy of said testing, comprising in combination, a screen arranged for defining a test site portion within the body to separate said separable component from the test site within the screen, a resilient disk and a substantially parallel counterholder defining an aperture larger than said disk arranged at said test site portion with said screen connected to said counterholder, and said disk disposed in said aperture.
  • a testing device as defined in claim 17 including formwork for defining the body, said formwork defining an opening, a plate mounted at said opening, and said screen being fixed to said plate.
  • a testing device as defined in claim 17 including means protecting said aperture of said counterholder to keep any body portion with said separable component therein from passing into said test site portion.
  • a testing device as defined in claim 17 including a test disk placed in the substance at said test site portion at a position displaced from said resilient disk with a guide tube extending from the test disk for receiving a force transmission rod to displace it toward said resilient disk.
  • a testing device as defined in claim 17 including means protecting said aperture of the counterholder to keep any body portion with said separable component therein from passing into said test site.
  • a testing device as defined in claim 17 including a test disk placed in the substance at said test site portion spaced from said resilient disk defining therein an oblong opening dimensioned for passing a portion of a force exerting rod.
  • a testing device as defined in claim 17 including a test disk placed in the substance at said test site portion spaced from said resilient disk and having a force transmission rod thereon reaching toward the surface of said body.
  • a testing device as defined in claim 17 including a counterholder ring and a test disk attached to a piston shaft, said test disk being embedded in said test site portion spaced from said resilient disc and said ring being of greater size than said test disk to thereby cause a conic frustum rupture of said substance toward said resilient disk when the forces exceed the strength of said substance.
  • a testing device as defined in claim 27 including a guide tube detachably fastened to said test disk for guiding said shaft.
  • the method of testing the momentary strength of a body comprising a setting substance, such as concrete comprising the steps of mounting formwork to confine materials of said body, removably mounting on said formwork an assembly which includes a measuring disk to be embedded in said substance, pouring said materials into said formwork to form said body and envelop said disk, detaching said assembly from said formwork, removing said formwork from said body to leave exposed a portion of said assembly accessible to pull said disk from said body to test the strength of said body, and applying a measurable load by means of said assembly to said disk to break it away from said body thereby identifying at the break away point the strength of said body.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Ceramic Engineering (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
US368325A 1972-06-12 1973-06-08 Method and apparatus for early strength testing of in-place concrete Expired - Lifetime US3861201A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT504472A AT320313B (de) 1972-06-12 1972-06-12 Verfahren und Vorrichtung zur Festigkeitsmessung erstarrender Massen

Publications (1)

Publication Number Publication Date
US3861201A true US3861201A (en) 1975-01-21

Family

ID=3571293

Family Applications (1)

Application Number Title Priority Date Filing Date
US368325A Expired - Lifetime US3861201A (en) 1972-06-12 1973-06-08 Method and apparatus for early strength testing of in-place concrete

Country Status (4)

Country Link
US (1) US3861201A (de)
AT (1) AT320313B (de)
CA (1) CA982362A (de)
DE (1) DE2329679A1 (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4501153A (en) * 1981-02-23 1985-02-26 Ferenc Mehes Test machine for determining concrete strength
US4538467A (en) * 1984-01-06 1985-09-03 Stoll Ulrich W Method and apparatus for measuring the strength of hardened concrete
US5592283A (en) * 1995-04-03 1997-01-07 Westinghouse Hanford Company Testing of concrete by laser ablation
US6510743B2 (en) 2000-04-13 2003-01-28 Mcafee Ralph Glenn Reusable in situ concrete test specimen apparatus and method
CN102053036A (zh) * 2010-11-12 2011-05-11 中国水利水电科学研究院 拉压状态下混凝土构件高压水劈裂模拟实验设计方法和装置
US8082786B1 (en) * 2004-01-15 2011-12-27 Robert Akins Work capacities testing apparatus and method
US8752428B2 (en) 2004-01-15 2014-06-17 Robert Akins Work capacities testing apparatus and method
US20150330876A1 (en) * 2014-05-15 2015-11-19 H. Joseph Buhac Compaction testing sampler assembly
CN105466774A (zh) * 2015-11-20 2016-04-06 苏交科集团股份有限公司 一种手持式混凝土压缩试验装置
RU2706390C1 (ru) * 2018-10-16 2019-11-18 Игорь Валериевич Торицын Способ определения прочности по глубине погружения дюбеля-гвоздя в тестируемый бетон и дюбель-гвоздь
US20220364967A1 (en) * 2020-11-19 2022-11-17 Shandong University Of Science And Technology In-situ test device for surrounding rock strength of bolt supported roadway and method thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006042500B4 (de) * 2006-09-07 2009-02-05 Bilfinger Berger Ag Vorrichtung zur Untersuchung von Materialeigenschaften eines Baustoffs
CN114324009B (zh) * 2022-01-18 2022-06-17 东北石油大学 拉-剪应力条件下各向异性岩石复合断裂韧性测试装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2356327A (en) * 1941-12-13 1944-08-22 Protectoseal Company Of Americ Self-venting tank valve
US3541845A (en) * 1968-03-29 1970-11-24 Peter Kierkegaard Hansen Method for testing the strength of the material of cast structures,particularly concrete structures
US3595072A (en) * 1969-07-22 1971-07-27 Owen Richards Concrete testing means

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2356327A (en) * 1941-12-13 1944-08-22 Protectoseal Company Of Americ Self-venting tank valve
US3541845A (en) * 1968-03-29 1970-11-24 Peter Kierkegaard Hansen Method for testing the strength of the material of cast structures,particularly concrete structures
US3595072A (en) * 1969-07-22 1971-07-27 Owen Richards Concrete testing means

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4501153A (en) * 1981-02-23 1985-02-26 Ferenc Mehes Test machine for determining concrete strength
US4538467A (en) * 1984-01-06 1985-09-03 Stoll Ulrich W Method and apparatus for measuring the strength of hardened concrete
US5592283A (en) * 1995-04-03 1997-01-07 Westinghouse Hanford Company Testing of concrete by laser ablation
US6510743B2 (en) 2000-04-13 2003-01-28 Mcafee Ralph Glenn Reusable in situ concrete test specimen apparatus and method
US8752428B2 (en) 2004-01-15 2014-06-17 Robert Akins Work capacities testing apparatus and method
US9439594B2 (en) 2004-01-15 2016-09-13 Robert Akins Work capacities testing apparatus and method
US8082786B1 (en) * 2004-01-15 2011-12-27 Robert Akins Work capacities testing apparatus and method
CN102053036B (zh) * 2010-11-12 2013-10-02 中国水利水电科学研究院 拉压状态下混凝土构件高压水劈裂模拟实验设计方法和装置
CN102053036A (zh) * 2010-11-12 2011-05-11 中国水利水电科学研究院 拉压状态下混凝土构件高压水劈裂模拟实验设计方法和装置
US20150330876A1 (en) * 2014-05-15 2015-11-19 H. Joseph Buhac Compaction testing sampler assembly
US9671385B2 (en) * 2014-05-15 2017-06-06 H. Joseph Buhac Compaction testing sampler assembly
CN105466774A (zh) * 2015-11-20 2016-04-06 苏交科集团股份有限公司 一种手持式混凝土压缩试验装置
RU2706390C1 (ru) * 2018-10-16 2019-11-18 Игорь Валериевич Торицын Способ определения прочности по глубине погружения дюбеля-гвоздя в тестируемый бетон и дюбель-гвоздь
US20220364967A1 (en) * 2020-11-19 2022-11-17 Shandong University Of Science And Technology In-situ test device for surrounding rock strength of bolt supported roadway and method thereof
US11703432B2 (en) * 2020-11-19 2023-07-18 Shandong University Of Science And Technology In-situ test device for surrounding rock strength of bolt supported roadway and method thereof

Also Published As

Publication number Publication date
CA982362A (en) 1976-01-27
AT320313B (de) 1975-02-10
DE2329679A1 (de) 1973-12-20

Similar Documents

Publication Publication Date Title
US3861201A (en) Method and apparatus for early strength testing of in-place concrete
Johnston et al. A synthetic soft rock for laboratory model studies
Chen et al. Load transfer behavior of fully grouted cable bolts reinforced in weak rocks under tensile loading conditions
Anagnostopoulos et al. Physical and mechanical properties of chemically grouted sand
Noori et al. Behavior of steel fiber-reinforced cementitious mortar and high-performance concrete in triaxial loading
US10315955B2 (en) Annular fill compressible grout mix for use behind pre-cast concrete segment installed in time-dependent deformation tunnels
Aziz et al. Double shear testing of bolts
Guo et al. Experimental study on direct tensile properties of cemented paste backfill
Chen et al. A study of the shear behavior of a Portland cement grout with the triaxial test
US10647904B2 (en) Compressive grout mix for use in absorbing compressive or deformation stresses of subterranean formations
Malmgren Interaction between shotcrete and rock: experimental and numerical study
Zhu et al. Improved isotropically consolidated undrained triaxial test method for non-self-supporting materials
Dano et al. Behavior of uncemented sands and grouted sands before peak strength
Iwaki et al. A quality control method for shotcrete strength by pneumatic pin penetration test
Petersen LOK-TEST AND CAPO-TEST DEVELOPMENT AND THEIR APPLICATIONS.
Souza et al. Passing ability testing for self-compacting concrete
Thompson et al. Constrained thermal expansion as a causal mechanism for in situ pressure in cemented paste and hydraulic backfilled stopes
Tóth et al. Influence of impact preloading on the residual concrete cone capacity
SU1065776A1 (ru) Прибор дл сцеплени битума с камнем в асфальтобетоне
Wagemann et al. Influence of cement grouting on the microstructure of cement paste
Reddy et al. An experimental investigation on the strength properties of self curing concrete by using super absorbrnt polymer
Ekwulo et al. Predicting the workability of fresh concrete using simple pull-out test
Weber et al. Modelling the inflight construction of sand compaction piles in the centrifuge
Klink Cement and the elastic constants of concrete
Montero et al. Pull-out creep lab test for rock bolts embedded in soft rock-like material