JPH04219210A - Adjusting method for kneaded substance comprising hydraulic substance powder such as cement - Google Patents

Abstract

PURPOSE:To reduce the breezing water of a kneaded substance comprising hydraulic substance powder such as cement regarding the kneaded substance, and to obtain a product molded form having excellent strength. CONSTITUTION:When water is added to hydraulic substance powder and a kneaded substance is acquired, primary water adjusted so as to form states before and behind a capillary region centering around the capillary region is added and the powder is primarily kneaded so as to reduce a concretion by said powder and residual secondary water is added and the kneaded powder is finishing-kneaded, and said powder is passed through a kneading process, into which an aggregate is mixed, before finishing-kneading after primary kneading. Breezing is diminished sufficiently, and a product having excellent strength is acquired.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for preparing a kneaded product using a powder of a hydraulic substance such as cement, and is used for kneading and adjusting mortar or ready-mixed concrete using a 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 used in today's civil engineering,
It is an indispensable material in construction and other technical fields, and is commonly and widely used in precast products, cast-in-place, and other on-site construction, including spraying and injection methods.

[0003]In actual construction using this hydraulic material powder, it is necessary to prepare 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. A large portion corresponding to at least 90% of the cement (W/C) is added to the cement, and the remaining portion is added in the final stage of kneading to adjust the degree of fluidity.

However, in the conventional method, when the kneaded material is used to form the desired shape, a considerable amount of breathing water is generated, and the strength of the obtained molded product is not necessarily satisfactory. However, it is well known in the field that there are disadvantages and disadvantages such as large variations in the quality of the product.In the past, this was considered an unavoidable phenomenon in products made of this type of cement, and a certain amount of breathing was required. Taking time to finish the surface,
Alternatively, the composition should be determined and designed and constructed taking into account 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 completed these studies. 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, and the peak point of the kneading torque by the mixer is adjusted so as to reduce agglomerates caused by the powder. Water-cement ratio 20-30 indicating the vicinity
%, and after this first kneading, the remaining secondary water necessary to form the desired water-cement ratio is added to perform a second kneading to form a fluid paste. [Patent Application No. 153974 of 1982 (Japanese Unexamined Patent Publication No. 1983-
No. 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 hardening 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 further improvement in product strength.

[0007]

[Means for Solving the Problems] The present invention has further conducted practical studies on the prior invention, and has developed a method for producing sand under the condition that only the primary water is added during the transition from the primary kneading to the finishing kneading. It is proposed to go through a kneading process in which one or both aggregates are mixed, as follows.

[0008] When adding water to a powder of a hydraulic substance such as cement to obtain a kneaded product, the powder was adjusted to form a funicular or capillary region and a capillary-like slurry region in the powder of the hydraulic substance. amount of primary water is added to perform primary kneading to reduce agglomerates caused by the powder, and after this primary kneading, the remaining amount of secondary water necessary to form the desired water-cement ratio is added. Final kneading is carried out, and after the above-mentioned first kneading and before final kneading, a kneading process is carried out in which aggregates of either sand or gravel or both are also mixed under the condition that only the above-mentioned primary water is added. 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 investigated various methods for preparing the paste, which is the basis for preparing the 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 circumstances between the cap and the lid are as clarified in the original invention, and after the first kneading with a primary water amount of 10 to 40%, the secondary kneading is performed by adding 40 to 10% of secondary water. The breathing water rate of the conventional method was lower than that of the conventional method at the same water-cement ratio (W/C), especially when the primary water was 20 to 3
When the primary and secondary kneading is performed with 0% secondary water and 30 to 20% secondary water, the breathing rate can be reduced to at least one third of the conventional method. 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 into powder of a hydraulic material such as cement. In detail, it is estimated that the formation of aggregates of fine cement powder particles is unavoidable, and in addition, when using the conventional general method in which the required amount of water is added at one time and kneaded, it is difficult to maintain an appropriate fluidity state. Because of the sufficient amount of water to form, even if kneading is performed for a long time, there is a very small possibility that the agglomerated agglomerates of cement powder particles that have formed will be dispersed, and a considerable amount of water will still be present. Even if this were the case, it is presumed that after a certain degree of dispersion, the degree of further dispersion would be extremely poor and the flow would simply be repeated.

On the other hand, when primary kneading is carried out in a funicular or capillary region where the amount of water is appropriately limited and a slurry region close to this capillary region (that is, in a capillary shape), the fannicular region centered on the capillary region is Even if a certain amount of water continuously enters between the particles in the cular or capillary slurry region, a considerable amount of air also exists, and the state of funicular F1 where air exists continuously, or at least the powder particles. This state has not yet reached a slurry state showing fluidity due to the continuous aqueous phase interposed between the particles, and in the first kneading that is added in such a state, the material to be kneaded does not substantially have fluidity. This indicates that even if the powder aggregation conditions due to gradual water addition are the same, the torque during the kneading operation is considerably high, and as a result, a considerable grinding effect can be obtained between the agglomerated agglomerates.

[0012] As a result of explicit observation and study of the kneaded material, the state in which the torque peak appears during the first kneading is that the particles are covered with liquid and do not come into contact with each other in a discontinuous state, and air is also present. 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 by intervening between particles) and also no air (which becomes a funicular state by intervening between particles), the torque increases at its peak. The torque peak obtained between the W/C of such cement paste varies depending on the type of hydraulic substance powder, etc., but it can be used for various types of Portland cement, blast furnace cement, early strength cement,
The results of the study on dispersant-added Portland cement, ultra-early strength cement, gypsum, alumina cement, etc. are W/
C is within the range of 20 to 30%, and since they are generally the same type used for the same construction, take a small amount and test it once, and record the torque of the stirring motor and the amount of water added. The amount of added water can be determined easily and accurately by this method, and the first point is near this amount of added water (the torque peak in the capillary state as described above is a point, so the funicular or slurry state close to the capillary before and after it).
The subsequent kneading provides a precise grinding effect between the coagulated agglomerates.

[0013]

[Operation] Primary water is added to the hydraulic substance powder in an amount adjusted to form funicular or capillary regions and capillary-like slurry regions, and primary kneading is performed to reduce agglomerates caused by the powder. By doing so, a kneaded product of the hydraulic material and water with few lumps can be obtained.

[0014] By adding sand or sand and coarse aggregate to the above-mentioned primary kneaded product and kneading the mixture, the added aggregate is mixed in the presence of a relatively small amount of water, which is only primary water. 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. .

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 ingredients. 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] The final kneading in the practice of the present invention means the final kneading when the method of the present invention is used. 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, the kneading may be carried out in a batch manner using a general mixer, but since the present invention involves a multi-stage process, continuous kneading is necessary for efficient kneading. It is preferable to use a commercial mixer. 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 according to the recent assembly line method. Of course, a plurality of mixers may be used, and the first mixer may perform primary kneading, the second mixer may perform intermediate kneading, and the third mixer may perform final kneading, respectively.

[0018]

[Embodiments] The details of specific embodiments of the present invention will be explained below, with appropriate comparisons with those of the prior invention described above.

Example 1 Ordinary Portland cement and Oigawa B sand (5 mm or less, FM: 3.09, JISA1
Specific gravity according to 109 is 2630Kg/l, water absorption rate is 1.4
3%, moisture content 3.41%), and sand-cement ratio (S/
C) was varied in the range of 1 to 5, and the primary water (W1) was kept constant at 24% of the amount of cement, and the primary kneading was performed at a torque value 0.1 to 0.2 A lower than the peak point of the mixer torque. Then, secondary water (W2) was added and the following three methods (a), (b), and (c) were adopted for secondary kneading (C is cement, W is water, and W1 is (primary water, W2 is secondary water, S is sand). In other words, → indicates kneading, and the kneading time is 60 seconds, but in order to make the overall kneading time the same (
The kneading time after the addition of S+W2 in c) was 120 seconds.

[0020] As mentioned above, specific formulations with S/C of 1 to 5 are shown in Table 1 below. The amount of secondary water was determined by subtracting the water amount of W1/C from W/C and the amount of water measured by the amount of water adhering to sand.

[0021]

[Table 1]

In other words, the above-mentioned (b) is according to the present invention, and (a) and (c) are comparative examples according to the original invention, but the above-mentioned S/C and (a) The properties and breathing rate of each mortar obtained by kneading and adjusting in combination with (c) are as shown in Table 2 below.

[0023]

[Table 2]

That is, the unit volume weight is summarized separately in FIG. 1, and the cylindrical penetration is summarized in FIG. 2, as shown in FIG.
3, α10 is 2.0 or more, and the breathing rate is as shown in FIG. 3 together with (d), which is a conventional general product in which the same compounding composition is added and kneaded at the same time, and (b) according to the present invention. In any case, it was confirmed that breathing was significantly reduced, and the strength was also favorable.

The cylindrical penetration shown in FIG.
This method is based on the method of JP-A-57-108637), in which a cylindrical object is penetrated into the kneaded material under conditions of equal circumferential restraint conditions, and the total weight of the cylindrical object is divided by the penetration volume. The difference between the value and the apparent specific gravity of the kneaded material is defined as the α value, and α10 is the α value converted when the penetration depth is 10 cm.

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

[0027]

[Table 3]

In other words, the surface water content in sand (S) is 0.
(surface dry) to 14% in 2% increments, and the specific adjustment of the surface moisture content is insufficient because it uses impact force to maintain the surface moisture content at a constant state. Water was further sprinkled and mixed to obtain the respective surface water percentages. (b)
The properties of each mortar obtained by kneading by this method and the average compressive strength of the resulting molded articles are shown in Table 4 below.

[0029]

[Table 4]

That is, favorable results can be obtained in any case, but it is particularly advantageous to use one with a surface water content of about 6% in terms of strength, and as 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 coarse aggregate, crushed stone with FM6.43, and S/a is the sand to coarse aggregate ratio, and an air entraining agent of sodium resin salt was added at 0.02% of the cement amount.

[0031]

[Table 5]

The kneading method is as follows (b1) and (b)
2). That is, (b1) is according to the present invention, and (b2) is a comparative example. (b1) C+W1 →S+G→W2 +Ad→(b
2) C+W1 +S+G→W2 +Ad→

003
3] The fact that → is kneading is the same as above, and the time is 90 seconds for each, but C+W in (b2) which is a comparative example
1 The kneading time after +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]

The one according to (b1) is more 2H than (b2)
After that, the breathing rate further decreased, and a product with almost no breathing and superior strength was obtained, confirming that it is an effective concrete. 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/cm2, and the compressive strength after 28 days was 354 Kg/cm2. cm2.

[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 amount of time and can efficiently produce products with excellent strength, making it a highly effective invention industrially.

[Brief explanation of the drawing]

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

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.

FIG. 4: In the device according to the present invention, S/C is 3.0, W
2 is a diagram summarizing the mortar properties when the surface water content of sand is variously changed under the conditions that /C68% and the water-cement ratio at the time of primary kneading is 24%.

Claims (3)

[Claims] 1. When adding water to a powder of a hydraulic substance such as cement to obtain a kneaded product, adjustment is made to form a funicular or capillary region and a capillary-like slurry region in the powder of the hydraulic substance. The amount of primary water is added to perform the first kneading to reduce agglomerates caused by the powder, and after this first kneading, the remaining amount of secondary water necessary to form the desired water-cement ratio is added. Then finish kneading.
After the first mixing described above and before the final mixing, a mixing process is performed in which aggregates of either sand or gravel or both are also mixed under conditions in which only the primary water is added. A method for preparing a kneaded material using powder of a hydraulic substance such as cement. Claim 2: Adding primary water to hydraulic material powder to
Hydraulic substance powder such as cement as set forth in claim 1, wherein fine aggregate such as sand is added to the next kneaded paste, intermediate kneading is performed, and then secondary water is added for final kneading. A method for preparing a kneaded material. 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.