Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Patent
1982-10-04
1985-02-26
Ruehl, Charles A.
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
G01N 308, G01N 3338
Patent
active
045011532
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a test machine for determining concrete strength, especially for performing quality tests of concrete structures or structural elements within the plant or at the site. The machine is provided with a loading unit loading the concrete until destruction. The loading unit applies tension on some part of the concrete and it is provided with a device for determining the crumbling strength causing destruction e.g. with a force measuring means. The force measuring means is set on a support arranged on the surface of the concrete to be tested.
In the field of concrete and reinforced concrete building, when either applying prefabricated structures or erecting monolithic buildings, there is needed the possibility to determine technical parameters of the solidified concrete, first of all the mechanical properties thereof. From the earliest days of building with concrete it has been customary to prepare particular test pieces, so-called test-cubes or more rarely test pieces of special form, which are loaded until destruction and from the crumbling strength a conclusion can be drawn in respect of the concrete strength.
These tests provide, however, only informatory results and full safety conclusions can not be drawn therefrom as to the mechanical properties of the completed structure. The first and most important reason for this resides in that, as a matter of course, the pouring circumstances of the test pieces differ from those of the concrete of the actual structure. Besides, solidifying of the raw concrete may also take place under substantially different conditions.
Experience has shown that the strength parameters measured on test pieces give an unrealistically good result. Thus, efforts have been made for a number of years to perform also mechanical tests based on fracturing samples taken from the actual structures and on evaluation of the results of these fractures.
In the course of this latter procedure, samples e.g. test cubes are cut out from the finished structure at predetermined locations, then these are loaded until fracture. Such a method can, however, in many cases not be used firstly on account of the damage to the structure and secondly because there can be some special reasons due to which the whole of the structure must not be broken down nor the load thereon shifted by the stress accompanying the cutting work. This was the motive leading to a solution wherein punches of different forms are embedded in the concrete material before it solidifies and from the force needed to extract them, a conclusion may be drawn as to the mechanical properties.
The experiences with this test method were not unambiguously advantageous since during extraction of the punch, the fractured cross section will be accidental i.e. it will have a different form and size in each case. Thus, in spite of carefully measuring the force, the measured value is not reliable enough due to the inaccurately known cross section. One of such measuring methods is described in U.S. Pat. No. 4,103,540.
More reliable tests than the above-mentioned "punch extraction" are those wherein from the values of the pore space and of the water-cement coefficient a conclusion is drawn to the concrete strength. One of these methods is described in the GDR Pat. No. 102,043. On more or less similar considerations are based also those accelerated methods for determining strength described in patents Nos. CD Pat. No. 2,607,919, U.S. Pat. No. 3,974,679 and Fr Pat. No. 2,323,149. All these solutions have the common deficiency that due to uncertain basic data, the conclusions to be drawn from the test will be vague.
A further advance in concrete testing was achieved by procedures in which the sample is cast in the concrete element to be tested. Such methods are to be found in the patents Nos., DE Pat. Nos. 1,917,242, 1,917,730 and U.S. 3,176,053. According to these methods so-called trial cores are cast in and then removed from the concrete to be tested and thereafter they are loaded until fracture on a testing machine.
As most expedi
REFERENCES:
patent: 3176053 (1965-03-01), Stasio
patent: 3541845 (1970-11-01), Kierkegaard-Hansen
patent: 3595072 (1971-07-01), Richards
patent: 3861201 (1975-01-01), Kaindl
patent: 4103540 (1978-08-01), McLaughlin
Mehes Ferenc
Mozes Andras
LandOfFree
Test machine for determining concrete strength does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Test machine for determining concrete strength, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Test machine for determining concrete strength will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-511551