JPS6149806A - Method of compounding mortars - 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 Field of Industrial Application This invention relates to a method for preparing hydraulic cementitious compositions such as mortar and concrete (hereinafter referred to as mortars).

Problems to be Solved by the Invention According to the water-cement ratio theory, the strength of a hydraulic cementitious composition after hardening is determined by the mixing ratio of cement and water, and the smaller the amount of water per cement, the greater the strength. According to a recent theory, by setting and hardening near the minimum amount of water necessary for the hydration of cement, it becomes extremely strong, ensuring not only compressive strength but also tensile strength, bending strength, and shear strength. .

By the way, when preparing mortar, it is necessary to have workability (that is, it is necessary to have appropriate softness, fluidity, viscosity, and plasticity related to ease of dismantling operations such as mixing, driving, and molding before hardening). In order to ensure this workability, it is customary to mix in a much larger amount of water than is required for the hydration effect of cement, and various admixtures are added to reduce the amount of water.However, the hydration effect When the required minimum amount of water is reached, the amount of water becomes extremely small, making it difficult to ensure workability. Stirring and mixing during the hydration reaction are important, but they are also difficult to carry out, since they are greatly affected by the properties, degree of air bubbles, etc.

This invention aims to solve the above-mentioned conventional problems by blending waste water in the form of granular ice.

Means to Solve the Problem The gist of this invention is to stir and mix granular ice with cement and aggregate, then melt the granular ice, and cause the resulting water to undergo a hydration reaction with cement. By stirring and mixing water in granular form, homogeneity is maintained, and the hydration effect is delayed by keeping each mixed material at a low temperature.
A small amount of water is evenly dispersed throughout the cement, and the workability of mixing and stirring is improved. Note that the granular ice can be melted by natural means, heating, pressurization, or the like.

By the way, the melting time of granular ice mixed in cement is
If heat is transferred by thermal conduction, the following equation is obtained.

Where, t: Melting time of ice ('h) m: Specific gravity of ice, 920 Kf/m2F: Heat of melting of ice, 80 to 1/9 λ: Cement thermal conductivity, 0.2 KC, ll/ m
h'C (average of actual measurements) Nu: average Nusselt number, 2 (particle size 0.05 to 25) θ0 = ambient temperature (°C) ro radius of two granular ice (e) and granular ice diameter and ice melting time The relationship is as shown in FIG. 1, and the mixing time is appropriately selected from this.

Example (a) Material cement Ordinary Portland cement sand Fujitsuki river sand Particle size 25 questions or less Particle size distribution 0.3 or less 15% 0.3-0.6 28% 0.6-1.2 33% 12-25 24% Absolute dry specific gravity 2.7 Ice particle size 3. Q Particle size distribution of mm or less 1.0 questions or less 37% 1.0-2.0 41% 2.0-3.0. 22% (b) Preparation (weight ratio) The above materials were stirred and mixed at room temperature at 15°C and cured under pressure.

The maximum value of the stirring and mixing time was determined based on the particle size and room temperature.

The results of the compression experiment under the above conditions are shown in the table below.

Moreover, the above results are shown as a graph in FIG.

In addition, the results of the bending test on the test specimen 2 were as follows:
The bending strength was 230 Kp/d.

Effects of the Invention The present invention has the above-described structure, and since cement, aggregate, and granular ice are stirred and mixed, they can be mixed and stirred homogeneously. The water used for the hydration reaction is obtained by melting granular ice, but since it is homogeneously mixed and stirred, only a very small amount is required.

As a result, as shown in the experimental results, it is clear that the compressive strength, tensile strength and bending strength are significantly improved.

[Brief explanation of the drawing]

Figure 1 is a graph of the relationship between granular ice diameter and ice melting time, and Figure 2 is a graph of compression test results. No. 160, No. 160677 2, Invention
Name of method for blending mortars 3, Relationship with the case of the person making the amendment Patent i "Applicant's name 5, Date of amendment order JP 4 Neho 1 1939 Month, day (shipment date) 6, Inventions increased by amendment Number (1) Insert the following between lines 16 and 17 on page 2 of the specification: ``In addition, since mortars undergo a hydration reaction after adding water and gold and mixing, for example, in a concrete mixer plant. The concrete slurry made by the above-mentioned methods had a limited time in the pouring machine.For this reason, it was necessary to make it at all concrete mixer plants.'' (2) Between lines 4 and 5 on page 7 of the same page, the following is written: Insert. [Also, according to this preparation method, the water mixing time can be appropriately selected by adjusting the ice melting time depending on the diameter of the granular ice, and the presence of the granular ice keeps the mortar at a low temperature.
It delays the hydration reaction and lengthens the time required for pouring. Therefore, for example, the time constraints on mortar made in a concrete mixer plant can be relaxed, making it possible to supply it to a wide range of areas. ” Procedural amendment September 17, 1985 1. Indication of the case Patent Application No. 160677 of 1988 2. Name of the invention Method for preparing mortars 3. Person making the amendment Relationship with the case Patent applicant 4. Agent Person: 1-1 Akasaka 5, 6-5-21 Akasaka, Minato-ku, Tokyo 107, Japan
Voluntary amendment 6, number of inventions increased by the amendment 7, full text of the specification subject to the amendment and drawing 8, description of the contents of the amendment: as attached Drawings: ``Figures 1 and 2'' were replaced with the attached drawing ``Figure 2''. 1 and 2”. Description 1, Name of the invention Method for preparing mortar 2, Claims (1) Granular ice is added to cement or cement and aggregate, etc. and stirred and mixed in the same phase, and then the granular ice is melted. A method for preparing mortar, which is characterized by causing a hydration reaction between water and cement. 3. Detailed Description of the Invention (Field of Industrial Application) This invention relates to a method for preparing hydraulic cementitious compositions such as mortar and concrete (hereinafter referred to as mortars). (Problem to be solved by the invention) According to the water-cement ratio theory, the strength of a hydraulic cementitious composition after hardening is determined by the mixing ratio of cement and water, and the smaller the amount of water to cement, the higher the strength. becomes. According to a recent theory, by setting and hardening cement near the minimum amount of water required for hydration, cement becomes extremely strong, ensuring not only compressive strength but also tensile strength, bending strength, and shear strength. However, when the minimum amount of water required for hydration is reached, the amount of water becomes extremely small, making it difficult to homogeneously mix mortar or densely fill the mortar. I couldn't get it. This invention was made in view of the above circumstances, and by supplying the water required for the hydration reaction with granular ice, it is possible to prepare homogeneous mortar even with an extremely low water/cement ratio, and it has a high hardening strength. The purpose of this paper is to propose a method for preparing mortars that can be used to obtain products. (Means for Solving Problems) The gist of the present invention is to add granular ice to cement or cement and aggregate, stir and mix them in the same phase, then melt the granular ice, and produce water. This is a method for preparing mortar, which is characterized by causing a hydration reaction with cement. In this method, granular ice has cement or fine aggregate attached to its surroundings, and is dispersed into particles sprinkled with powder, which is microscopically heterogeneous but macroscopically forms a homogeneous mixed system. Therefore, even if the amount of granular ice added is small, the granular ice is evenly dispersed, and after the ice melts, the melt water wets the surrounding materials to form a homogeneous mortar. If an equivalent small amount of water is added instead of granular ice, the water will wet some of the cement or aggregate and form agglomerates, and will not mix with the dry powder, making it impossible to obtain a homogeneous mortar. In addition, granular ice coated with cement or aggregate is difficult to melt because its outer surface is covered with a heat insulating layer, which is a good condition for achieving even stirring and mixing or delaying the hydration reaction. bring about. The smaller the particle size of the granular ice is, the more homogeneously it can be dispersed, and there is no fear that unmelted ice will remain after pouring and cause defects. If the surrounding temperature is low, even small-sized ice is difficult to melt, and powder such as cement covers the ice particles and can be stirred in a solid state, so there is little effect before and after the procedure of mixing aggregate etc. However, if the surrounding temperature is high, the particle size should be slightly larger to prevent the ice from melting during stirring, and fine particles such as cement or a mixture of cement and sand should adhere to the ice surface quickly. It is desirable to mix in aggregate etc. later. In this preparation method, it is preferable to supply the entire amount of water required for the hydration reaction of cement as granular ice.
In actual preparation, since sand and its fine aggregates contain some water, the amount of water excluding the water accompanying these raw materials is supplied in the form of granular ice. The melting time of granular ice mixed in mortar depends largely on the ice temperature and water diameter. For this purpose, the time required for the hydration reaction of mortar can be controlled by appropriately selecting the ice temperature and water diameter. The mortar prepared in this way is pressurized in a formwork, compacted by centrifugal force in a centrifugal formwork, or compacted by vibration from a vibrator, etc., and is densely packed and cast. . At the same time, as the granular ice melts, the entire mortar is evenly wetted, causing a hydration reaction, and even at a low water-to-cement ratio, the mortar exhibits excellent homogeneity and the original strength of the mortar. (Example) (Example 1) (a) Material. Cement Ordinary Portland cement sand Fujikawarakawa sand Particle size 2.5 mm or less Particle size distribution 0.3 mm or less 15% 0.3-0.6 28% 0.6-12 33% 1.2-2.5 24% Bone dry Specific gravity 2.7 Ice Particle size 3, Omm or less Particle size distribution 1, 0mm or less 37% 1.0-2.0 41% 2.0-3.0 22% (b) Mixture (weight ratio) The above materials are mixed into 15% The mixture was stirred and mixed at room temperature (°C), pressure molded, and then sealed and cured. The optimum stirring and mixing time was determined based on the particle size and room temperature. A test specimen was made under the above conditions, and its compressive strength was determined. The results are shown in Table 1. Table 1 28-day strength unit kg/cd (Example 2) A test specimen in which granular ice and cement were stirred and mixed in the same phase, cement was attached to the surface of the granular ice, this was pressure-formed, and then sealed and cured. 28th of the material ordinance) was created. The relationship between the water/cement ratio and the compressive strength and bending strength is shown in Table 2. (Example 3) Granular ice was added to cement and sand (mixing ratio 1/2), mixed with stirring in the same phase to prepare mortar, and a test specimen (28 days old) was prepared by pressure molding and sealing curing. . The relationship between the water/cement ratio and the compressive strength and bending strength is shown in Table 3. Sand: Sand produced for Fuji (surface dry with a grain size of 2.5 mm or less) Granular ice crushed with a ice slicer Table 3 (Example 4) Granular ice/cement/crushed 1/gravel*2 (0,30/ 1.0/1.5/1.5) concrete version 3 was mixed. *1: Maximum grain size 5mm, surface dry *2: Maximum grain size 25mm, surface dry Book 3: Fresh concrete slump, Ocm Using this concrete, floor height 275 cm, column cross section 40 x 40
cm, beam cross section 30 x 60c+++, slab thickness 1
A full-sized reinforced concrete model with dimensions of 2 cm and wall thickness of 12 cm was made with normal reinforcement. For pouring concrete, we used both a rod-shaped vibrator and a formwork vibrator to achieve dense concrete filling. Seven days after pouring the concrete, the formwork was removed and left to cure in the atmosphere. After 28 days, a total of seven test specimens (10cmφ x 20cmh) were cut from the lower, middle, upper, and beam parts of the columns and subjected to compression tests. I did this. Compressive strength is 611-713
kg/cn? The average weight was 662 kg/C1. The relationship was determined.Water/cement ratio: 30% Mixing stirring time: 3 minutes The obtained cement paste was filled to a height of 12 cm into a square plywood cylinder (thickness: 9 mm) with a bottom surface of 7 cm x 7 cm, and a 5 cm high center was filled with the cement paste. The partial position was used as the temperature measurement point. Cement paste was prepared using granular ice at two temperatures of -2℃ and -26℃ and water at room temperature as a comparative example, and the elapsed time and temperature change were determined. The results are shown in the graph of Figure 1. The elapsed time until the temperature peak due to the hydration reaction of the cement paste varies depending on the temperature of the granular ice, and the curing time can be controlled depending on the temperature of the material used. ( Example 6) By this preparation method, the water/cemen l-ratio was 20% and 30%.
, 40%, and 60% cement pastes were made, and the relationship between the material age and shrinkage strain of the cured products was determined. The result is the second
It was as shown in the graph. In addition, the cured product has a diameter of 5 cm,
A cylinder with a height of 10 cm, a room temperature of 15°C, and a relative humidity of 6.
Shrinkage strain was measured under 0% conditions. As is clear from this graph, by using this blending method and a low water/cement ratio, it is possible to produce a cured product with extremely small shrinkage strain. (Effect of the invention) This invention consists of the above configuration. This preparation method uses granular ice instead of water and stirs and mixes in the same phase to create mortar. Therefore, even at a low water/cement ratio, the granular ice is evenly dispersed, and after the granular water is melted, a homogeneously water-wet mortar is obtained. When these mortars are combined with forming means such as pressure molding, centrifugal molding, or vibration compaction, the high strength inherent to mortars with a low water/cement ratio is exhibited in the hardened product. In addition, it is possible to adjust the melting of ice by adjusting the temperature of the granular ice or the diameter of the water, controlling the amount of melted water, and at the same time keeping the mortar at a low temperature, delaying the hydration reaction, and extending the time until pouring. . Therefore, for example, the time limit for mortar made in a concrete mixer plant can be alleviated, making it possible to supply it to a wide range of areas. 4. Brief explanation of the drawings Figure 1 is a graph of the correlation between the elapsed time and temperature of the paste to cement 1 in Example 5, and Figure 2 is the graph of the correlation between the age and drying shrinkage strain of the cement paste in Example 6. be. Figure 2 OU voice

Claims (1)

[Claims] 1. A method for preparing mortars, which comprises stirring and mixing granular ice with cement aggregate, then melting the granular ice, and causing the water obtained thereby to undergo a hydration reaction with cement.