JPH0260484B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for placing cement compositions (hereinafter referred to as mortars) made by adding water to cement, aggregate, etc., such as mortar and concrete slurry, and kneading them. [Problems to be Solved by the Invention] There are many voids (0.5 mm or more) inside the cured product of mortar, which is a major factor in reducing the physical properties of the cured product. In addition, in order to improve the strength of the hardened mortar, some attempts have been made to use mortars with a low water-cement ratio, but mortars with a low water-cement ratio have poor fluidity, so they cannot be placed with the usual casting method. This tends to further increase the fluidization, and means to increase fluidization are required. This invention was made in view of the above circumstances. The purpose is to effectively remove relatively large voids (0.5 mm or more) called entrapment air that adversely affect strength and physical properties, and
A cement composition that can impart high strength even to mortars with a low water-to-cement ratio by increasing fluidity during pouring and significantly reducing voids in the hardened material obtained by pouring. The purpose is to propose a method of pouring. [Means for solving the problem] This method of placing mortar is to place mortar made by adding water to cement, aggregate, etc. and kneading it on a mounting plate with many through holes. The method is characterized in that the mounting plate is vibrated and the mortar is caused to fall through the through hole and placed. This method will be explained below using experimental examples shown in FIGS. 1, 2, and 3. In FIG. 1, a mounting plate 2 having a large number of through holes 3 is placed on the bottom of a horizontal formwork 1 with a flat bottom, and a bar-shaped vibrator 5 placed on a platform 4 that moves up and down is placed on the bottom of a horizontally placed formwork 1. The vibrating rod 6 extending in the direction and the mounting plate 2 are connected via a connecting rod 7 projecting from the center of the upper surface of the mounting plate 2 to assemble the driving device. In this state, mortar 8 is placed on the mounting plate 2.
The vibrator 5 is activated to vibrate the mounting plate 2, and at the same time, the mounting plate 2 is gradually pulled upward. The mortar 8 on the mounting plate 2 passes through the through hole 3 and falls into the formwork 1 below. The mounting plate 2 is gradually raised at a speed commensurate with the rising speed of the surface of the mortar 8 in the formwork 1, and a predetermined amount of mortar 8 is cast into the formwork 1 as shown in Fig. 3. . Incidentally, at the end of pouring, a convex portion 8 is formed on the upper surface of the mortar 8 at a position corresponding to the through hole 3. Further, when pouring, it is preferable to continuously pour the through holes 3 of the mounting plate as close as possible to the already hammered mortar surface. The shape of the holes in the perforated plate used in this pouring method is not only a circular cross section, but also a triangular or square polygonal cross section, with a diameter of several mm to several cm, and the diameter of the mortar aggregate. , slump value, etc. are considered. For example, in the case of mortar with sand grain size D≦1.2 mm in Experiment No. of the experimental example described later, the hole diameter is 7.8 mm.
mm, a circular cross section was suitable. The vibration frequency is 6000~
The range was around 14,000 vpm, and in the experimental examples described later, suitable results were obtained with vibrations of 12,000 vpm. [Function] When mortar is at rest, the solid particles are in contact with each other and are stable. However, with this casting method, the mortar is subjected to vibrations, and in the process of falling from the top of the mounting plate through the through hole. , the solid particles become disengaged due to the indentation force accompanied by intense vibrations, lose resistance to shearing force, and become liquefied, resulting in significantly increased fluidity. Therefore, the defoaming of air bubbles in the mortar is promoted, and a cured product with extremely few voids can be produced without producing any defects when filling and pouring into a mold. [Example] Mortar with the composition and properties shown in Table 1 was made,
Test specimens were prepared by casting and curing using the casting method shown in FIGS. 1, 2, and 3 above. At the same time, a test specimen of a comparative example was made by hand pouring and compared.

[Table] The porosity, apparent specific gravity, bending strength, and compressive strength of the test specimens made in the experimental examples and comparative examples were
Shown in the table.

【table】

[Development items]

FIG. 11 shows an example of a pouring device suitable for carrying out the other pouring method on a practical scale. This device has a mounting plate 2 having approximately the same shape and area as the bottom surface of a horizontally placed formwork 1, and the mounting plate 2 has vibrators 10, 10
and a hanging stand 12 on which a vibration isolator 11 is attached.
It is installed horizontally under the roof, and is suspended from a lifting machine so that it can be raised and lowered freely. The mortar 8 to be placed is fed onto the top surface of the mounting plate 2, and the vibrator 1
0 is activated to give vibration to the mounting plate 2 and cause the mortar 8 to fall from the through hole 3 into the formwork 1. The mounting plate 2 is raised by a lifting machine at a speed commensurate with the rise of the surface of the mortar 8 while remaining close to the surface of the mortar, and a predetermined amount of mortar 8 is placed inside the formwork 1. Pour concrete. [Effects of the Invention] The present invention is as described above. According to this method, voids in a cured mortar can be significantly reduced and high strength can be developed. It also has the advantage of being able to cast mortar with good workability using a simple device. It should be noted that since convex portions are formed on the surface of the cast mortar as it is, it is easy to attach it when applying a finishing material.

[Brief explanation of drawings]

Figures 1, 2, and 3 are partial cross-sectional views of the experimental pouring method and equipment in the order of the steps; Figures 4, 5, 6, 7,
Figure 8 is a correlation graph between the void diameter and integrated void area for Experiment Nos. 9 and 1, respectively.
Figure 0 is a correlation graph between the cavity diameter and the number of cavities for each experiment No., Figure 11 is a vertical cross-sectional view of a pouring installation diagram suitable for implementing this pouring method on a practical scale, and Figures 12, 13, and 14 are Figures 15 and 16 a and b are photographs showing the surface particle structure of the test specimens of Experimental Examples and Comparative Examples, respectively. 1...Formwork, 2...Placement plate, 3...Through hole, 4...
... Frame, 5 ... Rod-shaped vibrator, 6 ... Vibration rod, 7 ... Connection rod, 8 ... Mortar, 9 ... Convex part, 10 ... Oscillator, 11 ... Vibration isolator, 12
...Hanging stand.

Claims (1)

[Claims] 1. A cement composition obtained by adding and kneading water to cement, aggregate, etc. is placed on a mounting plate with many through holes, and vibration is applied to this mounting plate to cause the cement composition to pass through the holes. 1. A method for placing a cement composition, the method comprising placing a cement composition by allowing it to fall through.