JPH0565324B2 - - Google Patents

Description

[Detailed description of the invention]

[0001]

[Field of Industrial Application] The present invention relates to a method for preparing a kneaded product using powder of a hydraulic substance such as cement, and is used for kneading and preparing mortar or ready-mixed concrete using powder of a hydraulic substance such as Portland cement. The present invention aims to provide an improved method that can reduce the amount of breathing water and produce a molded product with excellent strength.

[0002]

[Prior Art] Various cements such as Portland cement and other hydraulic substance powders are indispensable materials in today's civil engineering, construction, and other technical fields, and precast products include spraying and injection methods. It is commonly and widely adopted regardless of whether it is cast-in-place or other on-site construction.

[0003] By the way, in order to carry out actual construction using this hydraulic material powder, it is necessary to adjust it as a paste, mortar, or ready-mixed concrete. The amount of water necessary to obtain the desired fluidity and moldability is first added to the material powder, and then kneaded and adjusted. The cement is symmetrical to the
A large portion corresponding to at least 90% of the W/C) is added, and the remainder is supplemented in the final process of kneading to adjust the degree of fluidity.

[0004] However, with such conventional methods, when the kneaded material is used to form the desired shape, a considerable amount of breathing water is generated,
In addition, it is well known in the field that the strength of the obtained molded product is not necessarily satisfactory, and there are large variations in strength, resulting in disadvantages and drawbacks. It is considered an unavoidable phenomenon in products made by
It is said that the composition should be determined and designed and constructed by taking a certain amount of breathing time to finish the surface, or by considering a sufficient safety factor equivalent to that.

[0005] The present inventors have spent many years conducting detailed research and practical studies on preparing various kneaded products and obtaining products using the above-mentioned hydraulic substance powder, and have achieved these results. A number of proposals have been made regarding improvements, and one of the basic methods to solve the disadvantages and shortcomings of conventional general techniques as described above is to develop a kneaded product using the above-mentioned hydraulic material powder without adding aggregate. During the adjustment, an amount of primary water adjusted to form a funicular or capillary region is added to the hydraulic material powder to reduce agglomerates caused by the powder near the peak point of the kneading torque by the mixer. First kneading is carried out at a water-cement ratio of 20 to 30%, and after this first kneading, the remaining secondary water necessary to form the desired water-cement ratio is added to form a fluid paste. He proposed a second kneading process [Showa 56
Patent Application No. 153974 (Japanese Unexamined Patent Publication No. 58-56815)].

[0006]

[Problems to be Solved by the Invention] The above-mentioned prior art of the present inventors can reduce breathing water and considerably improve properties such as compressive strength of products obtained by molding and curing the kneaded product. Although this is an advantageous technology, the results of many practical studies regarding the prior art have shown that there are slight variations in the amount of breathing water generated and its strength, and that this breathing water can be further reduced. It was estimated that there is room for improvement in product strength as well.

[0007]

[Means for Solving the Problems] The present invention has further carried out practical studies on the above-mentioned prior invention, and the above-mentioned 1.
It is proposed to carry out a kneading process in which either sand or gravel or both aggregates are mixed under conditions where only water is added, as follows.

[0008] When adding water to a hydraulic substance powder such as cement to obtain a kneaded product, an amount adjusted to form a funicular or capillary region and a capillary-like slurry region with respect to the hydraulic substance powder. Primary water is added to perform primary kneading to reduce agglomerates caused by the powder, and after this primary mixing, the remaining secondary water necessary to form the desired water-cement ratio is added for finishing. After the above-mentioned first kneading and before final kneading, the mixture is subjected to a kneading process in which only the above-mentioned primary water is added, and one or both of sand and gravel aggregates are also mixed therein. A method for preparing a kneaded material using powder of a hydraulic substance such as cement.

[0009] To further explain the present invention as described above, the present inventors have studied various methods for adjusting the paste, which is the basis for preparing a kneaded product using cement as described above. It has been discovered that the generation of breathing water can be effectively reduced by performing this process twice or more and by greatly limiting the amount of water added during the first kneading.

[0010] The situation between the cap and the lid is as clarified in the original invention, and after the first kneading with the primary water amount of 10 to 40%, the secondary water is added at 40 to 10% and the second
The breathing water ratio of the second kneaded product is lower than that of the conventional method at the same water-cement ratio (W/C), especially when the primary water is 20 to 30% and the secondary water is 30 to 20%. The kneaded material can reduce the breathing rate to at least one-third of that achieved by conventional methods. However, the reason why the breathing rate can be greatly reduced and the strength of the product can be increased is that it cannot be confirmed visually when water is added to and kneaded with powder of a hydraulic substance such as cement. In detail, it is estimated that the occurrence of agglomerated nodules of fine cement powder particles is unavoidable;
In the case of the conventional general method in which the required amount of water is added and kneaded at a time, the amount of water is sufficient to form an appropriate fluid state, so even if kneading is performed for a long time, the cement powder particles once formed will be The possibility of the coagulated lumps being dispersed is extremely low, and even if a considerable amount of moisture is present, after the lumps have been dispersed to a certain extent, the degree of further dispersion is extremely low and the flow simply repeats. It is assumed that something like this will happen.

[0011] On the other hand, in the case of primary kneading in a funicular or capillary area where the amount of water is limited and a slurry area close to this capillary area (that is, in a capillary shape), the funnel or capillary shape centered around the capillary area is used. Even if a certain amount of water continuously enters between the particles in the slurry _region , a considerable amount of air also exists. The state has not yet reached a slurry state exhibiting fluidity due to the continuous aqueous phase intervening in the slurry, and the material to be kneaded has substantially no fluidity in the first kneading that is added in such a state. Even if the powder agglomeration conditions due to water addition are the same, the torque during the kneading operation is considerably high, and it is recognized that this produces a considerable grinding effect between the agglomerated agglomerates.

[0012] Furthermore, the state in which the torque peak appears during this primary kneading is due to the presence of air in a discontinuous state in which the particles are covered with liquid and do not come into contact with each other. It was confirmed that the liquid was in a capillary state in which a stable liquid film was formed due to the activity of the particle surface, and the liquid film was in a stable adsorption state on the particle surface and the liquid was in a capillary state. Since there is no air (which becomes a slurry state when liquid intervenes between particles) and also no air (which becomes a funicular state when this air intervenes between particles), the peak of torque increase occurs. becomes. The torque peak obtained between the W/C of such cement paste varies depending on the type of hydraulic material powder, etc., but it can be The results of examining Portland cement, ultra-early strength cement, gypsum, alumina cement, etc., show that the W/C is within the range of 20 to 30%, and they are generally the same type of cement used for the same construction. By taking a small amount of the water, testing it once, and recording the torque of the stirring motor and the amount of added water, the amount of added water can be easily and accurately determined. Therefore, the first is
The subsequent kneading provides a precise grinding effect between the coagulated agglomerates.

[0013]

[Operation] Primary water is added to the hydraulic material powder in an amount that is adjusted to form a funicular or capillary region and a capillary-like slurry region, thereby reducing agglomerates caused by the powder.
By subsequent kneading, a kneaded product of the hydraulic material and water with few lumps can be obtained.

[0014] By adding sand or sand and aggregate, which is coarse aggregate, to the above-mentioned primary kneaded product and kneading, the added aggregate is mixed in the presence of a relatively small amount of water with only primary water added. It functions like a ball in a ball mill to effectively grind the nodules with the above-mentioned hydraulic material powder, thereby further reducing the nodules and obtaining a kneaded product with further reduced breathing rate etc. .

[0015] That is, in the present invention, in order to further increase the grinding action, an aggregate such as sand or gravel, which is essential for mortar or ready-mixed concrete, is used, and such aggregate is generally mixed with other compounds. When this material is kneaded under conditions where the amount of water added is small, it imparts a shocking effect to the coagulated agglomerates, contributing to the reduction of the agglomerated agglomerates.

[0016] In addition, the final kneading in the implementation of the present invention means the final kneading in the case of the method of the present invention, and the final kneading is performed by adding other additives etc. to the kneaded product prepared according to the present invention. In the case of making a kneaded product, it is natural that kneading may be further performed after the additive is added.

[0017] Of course, kneading can be carried out in batches using a general mixer, but since the present invention involves a multi-stage process, it is necessary to mix continuously in order to efficiently knead. Preferably, a mixer is used. That is, primary kneading as described above is carried out on one side of the mixer having an appropriate length, intermediate kneading is carried out in the middle part while being transferred by a screw mechanism, and then final kneading is carried out on the other side. If such a method is adopted, it is possible to continuously obtain a kneaded material, and it is possible to perform kneading suitable for obtaining various concrete products, etc. according to the recent assembly line method. Of course, multiple mixers are used, and the first mixer performs the primary kneading, and the second
Intermediate kneading may be performed by a mixer, and final kneading may be performed by a third mixer, respectively.

【0018】

[Example] The details of a specific example of the present invention will be described below, with appropriate comparisons with the aforementioned prior invention.

[0019] Example 1 Using ordinary Portland cement and B sand from Oigawa (5 mm or less, FM: 3.09, specific gravity according to JIS A1109 2630 Kg /, water absorption rate 1.43%),
The sand-cement ratio (S/C) is varied in the range of 1 to 5, and the primary water (W ₁ ) is kept constant at 24% of the amount of cement, and the ratio is 0.1 to 0.1 from the peak point of the mixer torque.
First kneading is carried out at a low torque value of 0.2A, then secondary water (W ₂ ) is added and during the second kneading, the following (a) is carried out.
Three methods (b) and (c) were adopted (C is cement,
W is water, W ₁ is primary water, W ₂ is secondary water, S is sand). (a) C+W ₁ →W ₂ →S→ (b) C+W ₁ →S→W ₂ → (c) C+W ₁ →S+W ₂ → That is, → indicates kneading, and the kneading time is 60 seconds. In order to keep the overall kneading time the same, the kneading time after addition of S+W ₂ in (c) was 120 seconds.

[0020] As mentioned above, specific formulations with S/C of 1 to 5 are shown in Table 1 below. As for the secondary water, the amount obtained by subtracting the water amount of W ₁ /C from W/C and the water amount obtained by measuring the amount of water adhering to sand, respectively, was taken as the amount obtained by subtracting the amount of water from W/C.

【0021】

[Table 1] ■■■ Turtle shell [0003] ■■■

[0022] In other words, the above (b) is according to the present invention, and (a) and (c) are comparative examples according to the original invention, but the above S/C and (a) The properties and breathing rate of each mortar obtained by kneading and adjusting in combination with (c) and the average compressive strength of molded bodies obtained with these mortars are shown in Table 2 below.

【0023】

[Table 2] ■■■ Turtle shell [0004] ■■■

[0024] In other words, the unit volume weight is shown separately in Figure 1.
Regarding cylindrical penetration, as summarized in FIG. 2, the present invention (b) has α ₁₀ of 2.0 or more when S/C is 1 to 3, and Regarding the breathing rate, Figure 3 shows the same conventional general compounding composition added and kneaded at the same time (d)
As shown in the figure, it was confirmed that the material (b) according to the present invention achieved a remarkable reduction in breathing, and was also preferable in terms of strength.

[0025] The cylindrical penetration in FIG. 2 described above is based on the method proposed by the present inventors in Patent Application No. 184124 (Japanese Unexamined Patent Publication No. 108637/1982).
A cylindrical object is penetrated into the kneaded material under the same circumferential restraint conditions, and the difference between the total weight of the cylindrical object divided by its penetration volume and the apparent specific gravity of the kneaded material is calculated. α value, and α ₁₀ means the above penetration depth is 10
This is the above α value converted to cm.

Example 2 Using the same sand and cement as in Example 1, according to the method (b) of Example 1, kneading was carried out at a torque value 0.1A lower than the peak point of the mixer torque, and the S/C was intermediate. Assuming a constant value of 3.0, the formulation was as shown in Table 3 below, and the surface water content of the sand used was varied.

[0027]

[Table 3] ■■■ Turtle shell [0005] ■■■

[0028] In other words, the surface water content of the sand (S) is varied in 2% increments from 0 (surface dry) to 14%, and the specific adjustment of the surface water content is based on the impact force. Once the surface water percentage was brought to a constant state, insufficient water was further sprayed and mixed to obtain the respective surface water percentages. The properties of each mortar obtained by kneading by method (b) and the average compressive strength of the resulting molded articles are shown in Table 4 below.

[0029]

[Table 4] ■■■ Turtle shell [0006] ■■■

[0030] In other words, favorable results can be obtained in any case, but it is particularly advantageous in terms of strength to use one with a surface water content of about 6%, and for the breathing rate, a surface water content of 2 to 10% is particularly advantageous. More favorable reductions were obtained using sand, and these results are summarized separately in FIG. Example 3 Fresh concrete having the composition shown in Table 5 below was prepared. G is the coarse aggregate, crushed stone with FM6.43, and S/a is the sand to coarse aggregate ratio, and the air entrainment agent of sodium resin acid is added to 0.02 of the amount of cement.
% added.

【0031】

[Table 5] ■■■ Turtle shell [0007] ■■■

[0032] As the kneading method, the following two methods (b ₁ ) and (b ₂ ) were used. That is, (b ₁ ) is according to the present invention, and (b ₂ ) is a comparative example. (b ₁ )C+W ₁ →S+G→W ₂ +Ad→ (b ₂ )C+W ₁ +S+G→W ₂ +Ad→

[0033] The fact that → is kneading is the same as above, and the time is 90 seconds each, but this is a comparative example (b ₂ )
The kneading time after C+W ₁ +S+G was 120 seconds. The properties of the fresh concrete obtained and the compressive strength of the molded bodies made of the fresh concrete are shown in Table 6 below.

【0034】

[Table 6] ■■■ Turtle shell [0008] ■■■

[0035] In the case of (b ₁ ), the breathing rate is further reduced after 2 hours than in (b ₂ ), there is almost no breathing, and a product with better strength can be obtained, making it an effective concrete material. This was confirmed. In addition, when the same composition as in Table 5 was kneaded using the conventional method, the breathing rate after 3 hours was 2.2%, the compressive strength after 7 days was 220 Kg/cm ² , and the compressive strength after 28 days was 354 Kg/cm ² It was hot.

[0036]

Effects of the Invention According to the present invention as described above, when mixing and adjusting mortar or ready-mixed concrete using powdered hydraulic substances such as cement, the breathing rate can be sufficiently reduced to shorten the molding and finishing process. This invention can be completed within a certain period of time, and can efficiently produce products with excellent strength, making it a highly effective invention industrially.

[Brief explanation of drawings]

[Figure 1] S/C of the present invention and the prior invention
It is a chart showing the relationship between and unit volume weight.

FIG. 2 is a chart showing the relationship between cylinder penetration amount and S/C.

FIG. 3 is a chart showing the relationship between breathing rate and S/C for the present invention and comparative examples.

[Figure 4] In the device according to the present invention, S/C is 3.0,
W/C 68%, water-cement ratio during first mixing 24%
This is a diagram summarizing the mortar properties when the surface water content of sand is varied under the following conditions.

Claims (3)

[Claims] 1. When adding water to a powder of a hydraulic substance such as cement to obtain a kneaded product, the powder is adjusted to form a funicular or capillary area and a capillary-like slurry area in the powder of the hydraulic substance. Add the same amount of primary water and perform the first kneading to reduce agglomerates caused by the powder, and add the remaining secondary water necessary to form the desired water-cement ratio to this first kneading. After the above-mentioned first mixing and before finishing mixing, a mixing process in which only the above-mentioned primary water is added, and one or both aggregates of sand or gravel is also mixed is carried out. A method for preparing a kneaded material using powder of a hydraulic substance such as cement. [Claim 2] Primary water is added to the hydraulic material powder, and fine aggregate such as sand is added to the paste that is mixed for the first time, intermediate kneading is performed, and then secondary water is added for final kneading. A method for preparing a kneaded material using powder of a hydraulic substance such as cement according to claim 1. 3. The cement according to claim 2, wherein a coarse aggregate such as gravel is added together with a fine aggregate such as sand to the paste obtained by the first kneading, and the mixture is mixed intermediately. A method for preparing a kneaded material using hydraulic material powder such as.