JPH0371963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for producing ready-mixed concrete in a ready-mixed concrete production plant.

(b) Prior art In a ready-mixed concrete manufacturing plant, gravel, sand, cement, water, and admixtures measured in a measuring tank according to a predetermined mix are continuously fed into a mixer at predetermined intervals. Ready-mixed concrete is manufactured by mixing for a predetermined period of time.

(c) Problems to be solved by the invention In order to produce high-quality concrete, the first condition is to uniformly mix the materials fed into the mixer by kneading. However, as usual,
It takes a certain amount of kneading time to continuously feed the materials into the kneader and uniformly mix them by moving the materials using the kneading blades.

In view of the above points, the present invention proposes a method for producing high-quality concrete by uniformly mixing materials in a short time.

(d) Means for solving the problems The present invention has a plurality of kneading mechanisms, and cement and primary water are introduced into the first kneading mechanism 1 and kneaded to produce a fluid cement paste. At the same time, sand, gravel, the remaining amount of cement, and secondary water are put into the second kneading mechanism 2 and mixed for the required time, and then the cement paste mixed by the first kneading mechanism 1 is mixed into the second kneading mechanism The mixture is put into the kneading mechanism 2, and the tertiary water, the admixture, and the remaining amount of gravel are added and kneaded.

(e) Effect In the present invention, when producing ready-mixed concrete, first, cement and primary water are introduced into the first kneading mechanism 1 to form a fluid cement paste. In addition, in parallel with this, sand, gravel, the remaining amount of cement, and secondary water are introduced into the second kneading mechanism 2,
By kneading for the required time, a cement shell is formed around the sand and gravel. Next, the cement paste kneaded by the first kneading mechanism 1 is charged into the second kneading mechanism 2. Since the added cement paste has fluidity, it can be expected that if it is dispersed and added, it will spread to every corner in a short time and be mixed uniformly. By adding a mixture of tertiary water and an admixture to this and adding the remaining amount of gravel and kneading, it is expected that ready-mixed concrete can be produced uniformly and quickly.

(f) Examples The present invention requires a plurality of kneading mechanisms. The first kneading mechanism 1 kneads cement and water to make cement paste, and the second kneading mechanism 2 inputs various materials and the cement paste kneaded by the first kneading mechanism 1 to make the final product. It is used to mix fresh concrete.

In the present invention, the production of ready-mixed concrete consists of a cement paste kneading process by the first kneading mechanism 1, a dry mixing process and a wet mixing process by the second kneading mechanism 2.

(a) Cement paste kneading process Cement and primary water are introduced into the first kneading mechanism 1 and kneaded to form a cement paste. When this cement paste is introduced into the second kneading mechanism 2, it is preferable that it has fluidity so that it can be dispersed and introduced. In order to obtain a cement paste with fluidity, it is desirable that the weight ratio of primary water to cement be 0.5 or more, and an appropriate amount of the total amount of cement is put into the first kneading mechanism 1.

(b) Dry mixing process At the same time as cement and primary water are put into the first kneading mechanism 1, sand, gravel, remaining amount of cement, and secondary water are put into the second kneading mechanism 2 and kneaded. At this time, the amount of water added to the surface water of sand and gravel and secondary water should be adjusted so that the weight ratio of cement is about 0.2 to 0.3.
It is preferable to adjust the amount of water. This is because when the water-to-cement ratio is between 0.2 and 0.3, the adhesiveness of cement increases, and a strong shell of cement is formed especially around sand, resulting in a high-strength concrete. Also, if the entire amount of gravel is added, it will not be possible to mix it efficiently, so add only the amount that can be mixed efficiently. As a rough guide, the weight ratio of the amount of gravel to be added to the total amount of gravel is about 0.4 to 0.6.
Use gravel with as small a particle size as possible.

In this dry mixing, the water to cement ratio is preferably set at about 0.2 to 0.3, so when producing concrete that does not have a large amount of cement, the amount of water is enough to leak through the surface of the sand, When using sand or gravel, there is no need to add secondary water.

(c) Wet mixing process After completing the dry mixing for the required time, the fluid cement paste kneaded by the first kneading mechanism 1 is charged into the second kneading mechanism 2. When introducing this cement paste into the second kneading mechanism 2, it is preferable to take measures such as branching the input pipe 3 to disperse it as widely as possible.

During the dry mixing stage, the sand, gravel, and cement are dispersed almost uniformly, and since the cement paste is dispersed and added thereto, it is expected that uniform mixing will be possible in a short period of time. Next, the remaining amount of gravel temporarily stored in the post-measurement storage hopper 4 is started to be fed into the second kneading mechanism 2, and the admixture and tertiary water stored in the post-measurement liquid storage tank 5 are added. The mixture is dispersed into the second kneading mechanism 2 via the pump 6 and kneaded for a predetermined period of time. The reason why the material is temporarily stored in the storage hopper 4 and liquid storage tank 5 after measurement is to empty the measurement tank and prepare for the next measurement.

The tertiary water should be mixed with the admixture to ensure that the amount is sufficient to flow the admixture into the second kneading mechanism 2 without stagnation, so the weight ratio of the amount of tertiary water to the total amount of water input for kneading is about 0.1 or less. That's fine.

Next, a method for calculating the respective amounts of cement, gravel, and water to be separately introduced will be briefly explained.

The amount of cement input into the first kneading mechanism 1 is C1
Kg, the amount of cement to be put into the second kneading mechanism 2.
C2Kg, the amount of gravel fed into the second kneading mechanism 2 at the beginning of mixing is C1Kg (surface water amount: WG1Kg), the amount of gravel fed later is G2Kg (surface water amount: WG2Kg), the primary water amount is W1Kg, the secondary water amount is W2Kg , the tertiary water volume is W3Kg,
If the amount of surface water on the sand is WSKg, the following equation holds true.

(1) G=G1+G2 (G: total gravel amount) (2) C=C1+C2 (C: total cement amount) (3) WG=WG1+WG2 (WG: total gravel surface water amount) (4) W=W1+W2+W3+WS+WG (W: total water amount) (5)W1/C1=K1 (K1: water-cement ratio in the first kneading mechanism) (6) (W2+WS+WG)/C2=K2 (K2: water-cement ratio in the second kneading mechanism) (7)W3 = (W1+W2+W3)×K4 (K4: Set as appropriate below 0.1) (8)G1=G×K5 (K5: Set as appropriate between 0.4 and 0.6) (2), (4), (5), (6) From the formula, W2 = K2 x (K1 x C + W3 - W) / (K1 - K2) - (WS + WG), and if K1 and K2 are set, W2 can be found. Since K1 and K2 are the water-cement ratio in the first kneading mechanism 1 and the second kneading mechanism 2, K1
may be set appropriately between 0.5 and 0.5, and K2 between 0.2 and 0.3. If the calculated W2 is positive, the secondary water amount is W2Kg
If it is negative, the secondary water amount will not be input.

The divided input amount of each other material is also W1=W-(W2+W3+WS+WG) W3=(W-WS-WG)×K4 (K4 is set appropriately at 0.1 or less) C1=W1/K1 C2=C-C1 G1=G× K3 (K3 is set appropriately between approximately 0.4 and 0.6) G2 = G - G1, and the amount of gravel, cement, and water to be added separately is determined.

(F) Effects of the Invention In the present invention, while the first kneading mechanism 1 produces a fluid cement paste, the second kneading mechanism 2 mixes sand, gravel, residual cement, and secondary water. Dry mixing creates a highly sticky cement shell around the sand and gravel, into which the fluid cement is dispersed, so the material is dispersed quickly.
It can be expected to produce uniform ready-mixed concrete in a short time.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for carrying out the invention, and FIG. 2 is a chart of cycle times. 1...First kneading mechanism, 2...Second kneading mechanism.

Claims (1)

[Scope of Claims] 1 It has a plurality of kneading mechanisms, and the first kneading mechanism is supplied with an amount of cement that provides fluidity out of the total amount of cement, and the total amount of water is supplied to the second kneading mechanism as secondary water. The amount of primary water excluding the input water and the water for diluting the admixture is added and kneaded to create a fluid cement paste, and at the same time, sand and gravel are added to the second kneading mechanism. Of the total amount, gravel in an amount that does not overload the power of the kneading mechanism, the remaining amount of cement, and secondary water are added and mixed for the required time, then the cement paste mixed by the first kneading mechanism is transferred to the second kneading mechanism. A method for producing ready-mixed concrete, characterized by adding tertiary water, an admixture, and the remaining amount of gravel to the mixer and kneading it. 2. The method for producing ready-mixed concrete according to claim 1, wherein the weight ratio of primary water and cement input into the first kneading mechanism is 0.5 or more. 3 The weight ratio of cement to the amount of water added to the surface water and secondary water of the sand and gravel fed into the second kneading mechanism is
The method for producing ready-mixed concrete according to claim 1, wherein the ratio is 0.2 to 0.3. 4 In the second mixing mechanism, the weight ratio of the amount of gravel input at the initial stage of mixing to the total amount of gravel used for mixing is 0.4.
The method for producing ready-mixed concrete according to claim 1, which has a hardness of 0.6. 5 Injected into the second kneading mechanism together with the admixture 3
A method for producing ready-mixed concrete according to claim 1 for mixing with subsequent water.