JPH0715433B2 - Judgment method for young concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a method for determining whether or not a target penetration amount can be obtained for young concrete.

(Prior art) The strength control of concrete at the young age is usually performed based on the elapsed time after placing concrete and the result of the compression test by the strength control specimen. A direct strength control method using concrete is desirable. Therefore, it is necessary to study a strength control method for non-destructively determining the compressive strength of on-site concrete at the young age.

In the case of hardened concrete, various methods have been proposed, standardized, and standardized as non-destructive on-site strength estimation methods for concrete in the prior art.

However, there is no standard or standardized method for extremely low-strength concrete at the young age.

In terms of compressive strength of about 10 kgf / cm ^2, which is low strength, the dynamic and static penetration methods and rotation methods in sounding in the soil field are only standardized and standardized.

The standard penetration test by the dynamic penetration method is a method in which a turret is assembled and a conical tip portion is penetrated deep into the ground to measure the N value. The cone penetration test of the static penetration method is input or heavy. It is a method to measure the penetration resistance value by penetrating the conical tip with a weight, and the simple vane test of the rotary method is to push a vane (resisting blade) with a cross-shaped cross section into the ground.
This is a method in which the resistance moment value is measured by applying extremely slow rotation to the central axis.

(Problems to be solved by the invention) The standard penetration test of the dynamic penetration method is suitable for the determination of the depth and bearing capacity of the support layer, particularly the density of the sand layer, and the measurement of strength change,
In the case of clay it is suitable for hard clay, but on a large scale,
Not suitable for nondestructive testing.

The cone penetration test of the static penetration method is portable and convenient, but if the cone hits the coarse aggregate, the resistance value becomes large and accuracy cannot be expected.

The rotation type simple vane test is portable and convenient, but it is not suitable for nondestructive testing. If the vane hits the coarse aggregate, the resistance moment becomes large and accuracy cannot be expected.

The present invention has been proposed in view of the problems of the prior art with a simple structure, the penetration of young material concrete that can confirm the strength development of extremely low strength concrete at the young material age from the penetration test results. The point is to provide a quantity determination method.

(Means for Solving the Problems) In order to achieve the above-mentioned object, according to the strength determination method of a young age concrete according to the present invention, a projection-like mark in the penetration test device is provided with concentric circles, The cone-shaped tip penetration part is pressed against the concrete surface of extremely low strength at the time of young age and a predetermined load is applied, then the penetration test device is removed, and the protrusion mark remaining on the concrete surface is used. The amount of penetration of the tip penetration part is confirmed by the concave part, and the strength of the young concrete is determined by the penetration amount.

(Operation) According to the present invention, a hemispherical or conical tip penetrating portion of the penetration testing device is provided with concentric projection marks, and the concrete of extremely low strength at the young age is passed through the tip penetrating portion. When the penetration test device is removed after applying a predetermined load on the surface, concentric traces due to the protrusion marks remain on the surface of the young concrete as recesses, so that the remaining on the surface of the concrete. It is possible to confirm the amount of penetration by checking the number of mark marks, and to confirm the development of the compressive strength of the young-age concrete from the relationship between the amount of penetration and the compressive strength.

(Examples) The present invention will be described below with reference to illustrated examples.

(1) is a cylindrical body of a penetration tester (A) having a load scale (2) on its outer peripheral surface, and a shaft (5) with a handle (4) on a top lid (3) of the cylindrical body (1). Is slidably fitted into the shaft (5) and is fixed to the lower end portion of the shaft (5) which penetrates into the cylindrical body (1), and the bottom cover (7) of the cylindrical body (1). ) And a spring (8) is interposed between
Threaded rod portions provided above and below the connecting member (10) are screwed to the bottom lid (7) and the hemispherical or conical tip penetration portion (9).

A slit (11) is provided on the cylindrical body (1) in the generatrix direction, and a marker (12) attached to an appropriate portion of the spring (8) is seen through the slit (11), and a penetration test device ( By knowing the amount of deformation of the spring (8) in (A), the load applied by the device (A) can be known.

A projecting mark (13) is concentrically provided on the tip penetration portion (9).

Then, the penetration test apparatus (A) is vertically pressed against the surface of the young concrete (B) whose compressive strength is to be estimated, and the handle (4) is attached to the cylindrical body (1) (see FIG. 1). ) Is pressed to the bottom lid (7) side and a predetermined load is applied, and three recesses (C) are provided on the surface of the concrete (B). (See FIG. 2) At this time, it is confirmed that the concentric recesses (13 ') formed by the protruding marks (13) remaining in the recesses (C) are symmetrical as shown in FIG. Check the verticality of the penetration tester (A).

As shown in FIG. 4, when the recess (13 ') is asymmetric, it means that the penetration test device (A) is inclined.

Thus, the traces of the concentric circular protrusion marks (13) are checked, the number of concentric concave portions (13 ') remaining as the marks is checked, and the tip penetration portion (9) to the concrete (B) is checked. The amount of penetration of the concrete is confirmed, and from the relationship between the amount of penetration and the compressive strength, the manifestation of the compressive strength of the young-age concrete (B) is confirmed.

Since the penetration depth of the tip penetration part (9) becomes shallower as the strength of the young age concrete (B) is developed, the protrusion-like mark (13) provided on the tip penetration part (9) is used. Concentric traces become smaller. For example, the triple circle at the beginning becomes a double circle as the strength is developed, and no mark is left at the end.

Therefore, by providing concentric circular protrusion marks (13) at the positions and intervals where the marks change when the target penetration amount is reached, the target penetration depends on the presence or absence of the marks of the protrusion marks (13). It can be determined whether the quantity was obtained.

(Effects of the Invention) According to the present invention, as described above, the semi-spherical and conical tip penetrating portions of the penetrating test device are provided with concentrically projecting marks, and the tip penetrating portions are extremely low in the young age group. After applying a predetermined load by pressing on the concrete surface of strength, the penetration test device is removed, and thus the concave portion by the projecting mark left on the concrete surface causes the young material concrete of the tip penetration portion. It is possible to confirm the amount of penetration into the concrete, and the strength of the young material concrete can be confirmed from the correlation between the amount of penetration and the compressive strength.

Therefore, according to the method of the present invention, since it is possible to directly control the strength of young age concrete, it is easy to perform safety control and process control, and the slip foam method, which requires demolding at the stage when the concrete is extremely low strength, etc. In, it becomes possible to directly control the strength of concrete.

[Brief description of drawings]

FIG. 1 and FIG. 2 are side views showing a construction method of an embodiment of the method for judging the penetration amount of young age concrete according to the present invention, and FIGS. 3 and 4 are attached to the surface of young age concrete. FIG. 5 is a plan view showing a trace of a recessed portion by the penetration testing device, FIG. 5 is a partially longitudinal front view of the penetration testing device, FIG. 6 is a bottom view of the tip penetration part in the penetration testing device, and FIGS. 7 and 8 are It is the side view, respectively. (A) …… Penetration test device, (B) …… Young age concrete, (C) …… Recess, (9) …… Tip penetration part, (13)…
… Protrusion marks, (13 ′) …… Concave on the concrete surface.

Claims (1)

[Claims] 1. A predetermined load is applied by pressing a hemispherical or conical tip penetrating portion in which a projection-like mark is provided concentrically in a penetration testing device against an extremely low-strength concrete surface at the age of a young age. After that, remove the penetration test device,
Confirm the amount of penetration of the tip penetration portion by the concave portion by the protrusion mark remaining on the concrete surface, the strength of the young material concrete characterized by determining the strength of the concrete of the young material association by the penetration amount. Penetration amount determination method.