JPS6087010A - Method of kneading concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a concrete cross-conducting method capable of producing high-quality concrete.

Currently, research is progressing on concrete that has hardened sufficiently.
Although its properties and characteristics are now known, the effects of concrete cross-conducting conditions on solidified concrete are completely unknown. Therefore, the conventional mixing method only uses an induction type electric motor to rotate the mixer blades at a constant speed. This was limited to changing the distribution of water and aggregate, or considering the timing of each material's introduction.

However, when the concrete is mixed using the conventional method, the strength of the concrete after solidification varies widely and is unreliable, and there is a lot of waste, such as having to set a large safety factor at the time of design.

In view of the above-mentioned circumstances, the present invention changes the mixing speed (circumferential speed of the blade) between mortar mixing and concrete mixing after gravel is added, thereby reducing the variation in strength of concrete after solidification. This improves the quality and reliability of the system.

First, in the present invention, a drive source whose rotational speed can be controlled, such as a hydraulic motor or a DC motor having a constant output range as shown in Fig. 1, is used to change the mixing speed between mortar mixing and concrete mixing. There is.

That is, as shown in FIG. 2, the peripheral speed of the blade is driven to be high during mortar mixing (water, cement, and gravel mixing). The load torque during mortar kneading is small, so mortar can be kneaded at high speed. Once the mortar has been thoroughly mixed, gravel is added, but if the mixing speed is too high during mixing (concrete mixing) after adding the gravel, the gravel and mortar will separate, making it impossible to obtain high-quality concrete.

Therefore, when mixing concrete, reduce the mixing speed to an appropriate value.

As mentioned above, by increasing the kneading speed during mortar mixing, high quality concrete with no variation can be obtained.

The results of experiments conducted using a two-shaft concrete mixer are shown below.

Here, the kneading speed is the peripheral speed of the blade, and the quality of the concrete is evaluated by the compressive strength σ28 (~).

The test contents were as shown in Table 1, the blade peripheral speed R was FII-' rn/5ea R2 = 2 m/(8), the kneading time t was 6230%, and the number of tests was under the same conditions. The test was carried out 3 times, and 6 test samples were taken from inside the mixer each time to obtain a compressive strength of σ28.
was measured. The measurement results are shown in Table 2.

Table 1 (Composition) Note: W: Water C: Ordinary Portland cement S: Sand Water absorption rate 142% Specific gravity 2.65 Coarse particle ratio 268 C: Gravel Ad: Water reducing agent, Hozolith flat 5L Table 2 (Test data) Table 2 above As is clear from the test data, when the kneading time is the same and the blade peripheral speed is changed, both soft and hard mortars have a high uniform strength of 11 under the condition of high blade peripheral speed R2, and the average strength is higher than that of the average standard. Good quality concrete with little deviation was obtained.

This tendency is the same even when the mixing time is C+Ofl, and the quality of concrete depends on the peripheral speed of the blade during mortar mixing.

The blade peripheral speed and kneading time during concrete mixing may be such that the mortar and aggregate do not separate and the mortar uniformly adheres around the aggregate.

As described above, according to the present invention, it is possible to produce a comfried trough with less fluctuation in strength and high average strength.

In the above example, a drive source with characteristics as shown in Fig. 1 is used, and the kneading speed is controlled by a transmission using a wall constant speed drive source that changes the kneading speed by controlling the output of the drive source. Of course, you can change it.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the characteristics of the drive source used in the present invention, and FIG. 2 is a diagram showing the output characteristics of the drive source when the present invention is implemented. Patent applicant Ishikawajima Harima Heavy Industries Co., Ltd. Patent applicant Ishikawajima Construction Machinery Co., Ltd.

Claims (1)

[Claims] 1) A concrete mixing method characterized by mixing at high speed when mixing mortar and mixing at low speed when mixing concrete.