KR100946351B1 - A composite generation of low heat cement and that of manufacturing method - Google Patents

Abstract

PURPOSE: Coarse cement particles, a composition of low heat cement manufactured using mineral blending material, and a manufacturing method thereof are provided to produce the low heat cement without increasing a production price of the heat low cement using a powder collected in a grinding process of cement raw powder. CONSTITUTION: 25 ~ 75 mass % of coarse particle cement having a fineness of 1500~2500 cm/g is mixed with normal portland cement when placing mass concrete for reducing a temperature. 75~25 mass % of the coarse particle cement is mixed with the normal portland cement. The mixture reduces heat of hydration by reducing a reaction of hydration. The composition of the low heat cement comprises 70~90 mass % of the low heat cement and 30~10 mass % of fly ash.

Description

Composition of low heat cement manufactured using coarse grain cement and mineral admixture and its manufacturing method {A composite generation of low heat cement and that of manufacturing method}

The present invention relates to a low heat cement composition and a method for producing the same that can reduce the heat of hydration at low cost during the initial cement hydration reaction. Specifically, in order to lower the probability of cracking due to high heat of hydration during mass concrete construction, OPC and mineral admixtures are mixed with coarse grain cement separately collected during Portland cement (hereinafter referred to as OPC) production process, thereby showing excellent effect of reducing heat of hydration. It's about doing.

In general, when a large amount of concrete is poured to build the structure, the heat of hydration generated during the reaction of the concrete with water also greatly increases. This heat of hydration is generally between 25 and 25 ° C inside and outside the concrete structure. The above temperature difference is exhibited, and the temperature difference creates a stress difference between the inside and the outside of the structure, thereby causing a risk of cracking. Therefore, in order to prevent the occurrence of cracking of the structure, a method of lowering the heat of hydration of concrete is used in terms of construction by cooling the raw material with water or liquid nitrogen in advance or by buried a water cooling pipe in the concrete.

In other words, in recent years, the domestic construction market is accelerating the increase in the size, size and length of the structure as the demand for users and the project to expand social indirect capital are actively progressed. As a result, construction of large-scale mass concrete structures is increasing at domestic construction sites. When a large amount of cement is used for large-scale mass concrete structures, excessive heat of hydration is generated by the hydration reaction.

However, most construction sites in Korea still use only OPC, which has a high hydration calorific value, in such a situation, causing problems with low heat generation, which is a required performance of the structure.

On the other hand, Korean Patent Laid-Open Publication No. 2003-0085368 uses a paint composition composed of a phase change material to effectively accumulate thermal energy transferred to a paint composition during heating or cooling, and then to keep warm for a predetermined time even after heating or cooling is finished. Or coating compositions that can bring about a cold effect have been proposed. However, the latent heat capsule manufactured by this patent is difficult to be used in mixing with concrete or mortar because it may be injured or lower in strength when used in mixing with concrete. There is a problem.

In addition, Korean Patent Application Laid-Open No. 2001-0045384 discloses a method for preparing a microcapsule latent heat particulate slurry, but in this patent, melamine formaldehyde condensate is used as a surfactant, which is applied to concrete or mortar. This results in an increase in strength or a decrease in strength and the price competitiveness.

Meanwhile, Korean Patent No. 0683131 discloses a phase change material for concrete and a method of manufacturing the same. This patent is characterized by producing a phase change material including paraffin wax nonionic surfactant, anionic surfactant, and water, which are organic latent materials. However, the above-mentioned patent No. 0683131 has a merit of lowering a hydration temperature and improving initial strength by applying a microencapsulated creamy phase change material to concrete, but there is a problem that the encapsulation manufacturing process is complicated and expensive.

In addition, the cream-type microcapsule-type phase change material prepared by using organic paraffin wax and surfactant improved hydrophilicity to concrete by applying anionic surfactant, but the specific gravity is very low compared to concrete, so it may rise during concrete mixing process. There is a concern, because of the high unit price of the cream-like microcapsules containing the phase change material may be limited by the amount used, there are other problems that can be burdened on site construction.

On the other hand, the problem of cracking of mass concrete at the construction site is the most fundamental and essential element for the quality of the frame construction. Therefore, the initial heat of hydration must be reduced for this purpose. There is a method of reducing the amount of cement by substituting the mineral admixture, but in this case, it is a situation that adversely affects the durability degradation such as neutralization due to the substitution of a considerable amount of the mineral admixture.

Therefore, the method of reducing the heat of hydration, which is cheap, low durability and effectively reduces the heat of hydration by incorporating some mineral admixtures while increasing the particle size of cement to increase the particle size of cement, is best recognized in terms of preventing cracks and improving quality of concrete. have.

In order to solve such a problem in the prior art, in the present invention, the particle characteristics are collected in a coarse size in the crushing step of the OPC manufacturing process, and furthermore, it is essential for the conventional low heat generation cement production only by substituting a certain amount of the mineral admixture. It is an object of the present invention to provide a composition of low calorific cement which is economically produced without the need to perform the ingredient adjustment and additional processes and a method for producing the same.

In order to achieve the above object, in the present invention, OPC 75 to 75 to 75% by mass of coarse particles (A process cement of FIG. 1; hereafter referred to as MC) powder first discharged from the mill exit of the OPC grinding process. It provides a low heat cement having a composition of 25% by mass.

In the above embodiment, MC has an average diameter of 20 to 30 µm, a particle size distribution of 24 µm sieve passage of 45.0% or more, and a specific surface area of 1500 to 2500 cm 2 / g by the air blower. do.

In addition to the above embodiment provides another embodiment for achieving the object of the present invention.

In producing the low heat cement of the present invention, the powder collected in the grinding process of the cement raw material powder (coarse particles for low heat cement) without the need to modify the existing OPC production equipment or introduce additional processes to the existing production process ), It is possible to produce low heat cement without increasing the production cost of low heat cement.

The low heat cement of the present invention is expected to be widely used for reducing the initial heat of hydration due to the delay of condensation at the construction site, preventing the heat of hydration cracking. In particular, the low-heating cement of the present invention can be smoothly supplied according to the demand of the construction site can be a great effect in reducing the heat of hydration in the high-rise building and large-scale mass concrete site, the prevention of hydration heat cracking and construction costs.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. In addition, the configuration shown in the following examples are intended to help understanding of the invention to the last, and in no case should the technical scope of the present invention be limited to the above-described embodiments.

In the present invention, first, a low particle having a composition consisting of 75 to 25% by mass of OPC to 25 to 75% by mass of coarse particles (A-process cement of FIG. 1; referred to as MC) powder discharged from the mill exit of the OPC grinding process is referred to as MC. Provide exothermic cement.

In the above embodiment, MC has an average diameter of 20 to 30 µm, a particle size distribution of 24 µm sieve passage of 45.0% or more, and a specific surface area of 1500 to 2500 cm 2 / g by the air blower. do.

In another embodiment of the present invention, a fly ash having a density of at least 1,90 g / cm 3 and a powder of 2000 to 6000 cm 2 / g in a composition consisting of 25 to 75 mass% of MC and 75 to 25 mass% of OPC, It provides low heat cement having a composition consisting of 10 to 30% by mass relative to OPC + MC.

In another embodiment of the present invention, blast furnace slag fine powder having a density of not less than 2.70 g / cm 3 and a powder of 2000 to 6000 cm 2 / g in a composition composed of 25 to 75 mass% of MC and 75 to 25 mass% of OPC, It provides low heat cement having a composition consisting of 20 to 60% by mass relative to OPC + MC.

In another embodiment of the present invention, OPC + MC containing FA having a density of not less than 1,90 g / cm 3 and a powder of 2000-6000 cm 2 / g with a composition of 25 to 75 mass% of MC and 75 to 25 mass% of OPC A low calorific cement having a composition of 10 to 20% by mass with respect to OPC + MC and a BS having a density of 2.70 g / cm 3 and a powder of 2000 to 6000 cm 2 / g with respect to OPC + MC.

In one aspect of the present invention, 10 to 60 mass% of coarse particle powder (B process cement of FIG. 1; hereafter referred to as RC in FIG. 1) taken from a line conveyed to a grinder in a cyclone separator of an OPC grinding process, 90 to 40 mass% of OPC. It provides a low heat cement having a composition consisting of.

In one specific embodiment of the present invention, RC has a particle size distribution with an average diameter of 30 to 40 µm, a 24 µm passage through amount of 25.0% or more, and a powder degree of 1000 to 1200 cm 2 / g.

In one aspect of the present invention, OPC + RC is used for the FA powder having a density of 1,90 g / cm 3 or more and a powder of 2000 to 6000 cm 2 / g with a composition of 10 to 60 mass% of RC powder and 90 to 40 mass% of OPC. It provides a low heat cement having a composition of 10 to 30% by mass relative to.

In one aspect of the present invention, a BS having a density of at least 2.70 g / cm 3 and a powder of 2000 to 6000 cm 2 / g and 20 to OPC + MC in a composition consisting of 10 to 60 mass% of RC powder and 90 to 40 mass% of OPC. It provides a low heat cement having a composition consisting of ˜60 mass%.

In one aspect of the present invention, FA having a density of at least 1,90 g / cm 3 and a powder of 2000 to 6000 cm 2 / g in a composition consisting of 10 to 60 mass% of RC powder and 90 to 40 mass% of OPC is added to OPC + MC. It provides a low heat cement having a composition of 10 to 20% by mass with respect to OPC + MC of BS having a density of not less than 2.70 g / cm 3 and a powder of 2000 to 6000 cm 2 / g.

In another aspect of the present invention, the method comprises collecting the MC and mixing the collected powder to the OPC so that the mixing ratio of MC: OPC is 25 to 75 mass%: 75 to 25 mass% Provided are methods for producing exothermic cement.

In another aspect of the present invention, the method comprising collecting RC and mixing the collected powder with OPC such that the mixing ratio of RC: OPC is 10-60 mass%: 90-40 mass% Provided are methods for producing exothermic cement.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

A tube mill is used in the grinding process of OPC that is commonly used. A schematic diagram showing a general process for producing OPC by such a tube mill is shown in FIG. 1.

First, as shown in FIG. 1, clinker, gypsum and blast furnace slag are put into a tube mill cement mill and pulverized. The cement raw material crushed to an appropriate size is discharged (hereinafter referred to as "process A cement") and transferred to a cyclone separator through a conveying means such as a bucket elevator. In the cyclone separator, the pulverized cement raw material is classified according to the particle size. Coarse particles which are not sufficiently pulverized in the cement grinder are separated from the cyclone separator and returned to the cement grinder (hereinafter referred to as "B process cement"). The coarse particles returned are fed back into the cement grinder and subjected to the grinding process again. The cement powder ground within a certain size range through the cement mill is mixed with each particle collected in the main bag filter and the cyclone separator bag filter to form a powder for the final product.

Tables 1 and 2 show tables and graphs showing the particle size distribution of the above-mentioned A-process cement, B-process cement and OPC (Ordinary Portland Cement) as a final finished product.

As shown in Table 1 and FIG. 2, the process A cement has an average particle diameter of 24.9 μm, and shows a particle distribution in which the residual amount of 44 μm sieve is 49.0% and the amount of passage of the sieve of 24 μm or less is about 43.0% of the whole, The powder had a particle size of 35.8 μm in average particle size, 72.5% of 44 μm sieve residue, and about 24.9% of the total passage through the sieve of 24 μm or less.

Powder type Particle size distribution (%) Average particle size (㎛) Chezansa 1 μm pass Pass through 1 ~ 24 ㎛ Pass through 24 ~ 64 ㎛ 64 μm residue 44 μm R 88 μmR Cement of A process 4.7 43.0 40.0 11.5 24.9 49.0 12.9 Cement of B process 3.3 24.9 53.0 18.1 35.8 72.5 19.0 OPC 6.5 65.2 24.7 2.8 14.1 7.0 0.5

On the other hand, Table 2 and Figure 3 is a graph showing an example of the chemical composition and one example of the powder diagram measured for the cement of step A, the cement of step B and OPC, respectively.

Cement type Chemical composition (%) LSF SM IM Blaine powder degree (㎠ / g) LOI SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ K ₂ O Cement of A deduction 0.18 22.18 5.17 3.82 64.44 2.05 1.14 0.87 90.03 2.47 1.35 1908 Cement of B process 0.15 22.30 5.24 3.88 64.64 2.06 0.77 0.82 90.12 2.45 1.36 1087 OPC 0.35 21.88 5.02 3.66 64.18 2.01 1.83 0.92 90.44 2.52 1.37 3380

LOI: Loss on ignition, LSF: Saturation of lime, SM: Silicate rate, IM: Iron rate

As disclosed in Table 2 above, the cements of processes A and B have a lower LOI, SO ₃ , K ₂ O content and slightly increase SiO ₂ , Al ₂ O ₃ , CaO content compared to OPC produced as final products. Has characteristics. However, the cements of these A and B processes show similar values to OPC in lime saturation (LSF), silicic acid (SM) and iron (IM), and meet the quality specifications of medium heat Portland cement specified in KS L 5201. do.

Figure 4 is a graph showing the paste flow measured for the cement of step A, cement of step B and OPC. Overall, fluidity of process A cement was higher than that of OPC, but cement of process B was slightly lower than OPC. At this time, the reason that the fluidity is lowered in the cement of the B process seems to be due to the coarse particle size distribution in the narrow range close to the single particle size. However, the B process cement is a coarse particle, but mixing the mineral admixture and OPC in a specific ratio in the final low heat cement product in the present invention may obtain excellent fluidity and heat of hydration reduction.

5 is a graph showing the setting time measured for the cement of step A, the cement of step B and OPC. The cement of process A and cement of process B showed delayed condensation time compared to OPC. This is because the thicker the powder, the smaller the contact area with water and the lower the hydration rate.

6 is a graph showing the compressive strength according to the age of the cement measured for the cement of step A, cement of step B and OPC. The compressive strength of the cement of process A and the cement of process B, which has a low blain value, shows a low compressive strength at an early age and 28 days. It is analyzed that this is because the hydration rate is slowed due to the decrease of the contact area with water due to the low blain value, but the strength specifications of the four (low heat) cements were found to be satisfied. However, cements in the A and B processes are expected to exhibit almost the same or higher compressive strength as OPC in structural conditions that are hydrated for a long time, such as decades, as can be seen in Japanese strength steel concrete.

In the present invention, by using the cement of step A and the cement of step B as described above, even if the initial strength is low to produce a low heat cement intended for the purpose of the present invention. That is, after collecting and collecting the cement of step A and the cement of step B separately, the OPC produced by a conventional method, that is, mixed with OPC produced by a general facility in a special composition ratio, required by the specification Low heat generation cement that satisfies the quality can be produced in an economical way.

Specifically, the low calorific cement according to the present invention has a composition consisting of 25 to 75 mass% of cement of A process and 75 to 25 mass% of OPC, and 10 to 10 cement of process B, which is returned from the cyclone separator to the cement grinder. It has a composition consisting of 60 mass% and OPC 90-40 mass%.

In preparing the low heat cement according to the present invention as described above, it is preferable that the powder of the low heat cement is mixed so as to be in the range of 2000 to 3000 cm 2 / g. The powder range is a range that can be classified in the line that is returned to the grinder from the mill exit and the cyclone separator of the current OPC production line, corresponds to the range to ensure the initial heat reduction performance required in the field. However, when the powder degree exceeds the above range, it shows an initial heat of hydration similar to that of OPC, making it difficult to secure the required level of heat of hydration at a low powder level.

When producing the low heat cement according to the present invention, it is preferable to mix 3-5 minutes in a powder mixer in the mixing step. This is because when the low heat cement coarse particles having low powder level and OPC are mixed for 3 to 5 minutes with a powder mixer, each powder is evenly mixed to maintain an optimal dispersion state. This is because when added, an even hydration reaction is performed, which is advantageous for reducing the heat of hydration.

Example 1

When mass concrete is poured, MC having 1500 to 2500 cm 2 / g of powder collected from the mill mill outlet during OPC manufacturing process is mixed at 25 to 75% by mass relative to the mass of OPC to reduce the heat of hydration. The results of measuring the temperature rise by the simple insulation of concrete using the cement produced by the combination are shown in Table 3 below.

W / C (%) MC substitution rate (%) Temperature rise at peak temperature (??) 50 0 (OPC) 14.7 25 14.6 50 12.5 75 11.4

Compared with OPC, the peak temperature was lowered as the substitution rate of MC increased.

Example 2

In the second embodiment of the present invention, FA is mixed with 10-30 mass% of the mass of OPC + MC in the method of the first embodiment. The result of measuring the temperature increase amount by the simple insulation of concrete using the cement produced by the combination is shown in Table 4 below.

W / C (%) MC substitution rate (%) FA substitution rate (%) Temperature rise at peak temperature (??) 50 0 0 (OPC) 14.7 25 10 20 30 14.4 13.6 12.0 50 10 20 30 11.5 11.1 10.5 75 10 20 30 11.1 10.7 9.8

Compared with OPC, the peak temperature decreased with increasing MC substitution rate and decreased with the combination of FA.

Example 3

In the third embodiment of the present invention, the BS is mixed with 20 to 60% of the mass of the OPC in the method of the first embodiment. The result of measuring the temperature increase amount by the simple insulation of concrete using the cement produced by the combination is shown in Table 5 below.

W / C (%) MC substitution rate (%) BS exchange rate (%) Temperature rise at peak temperature (%) 50 0 0 (OPC) 14.7 25 20 40 60 12.7 12.2 8.4 50 20 40 60 11.3 10.3 8.1 75 20 40 60 11.1 9.8 7.9

Example 4

In the fourth embodiment of the present invention, FA and BS are mixed in the method of the first embodiment by mixing 10-20 mass% + 20-40 mass% relative to the mass of OPC. The result of measuring the temperature increase amount by the simple insulation of concrete using the cement produced by the combination is shown in Table 6 below.

W / C (%) MC substitution rate (%) FA + BS substitution rate (%) Temperature rise at peak temperature (??) 50 0 0 (OPC) 14.7 25 10 + 20 10 + 40 20 + 20 20 + 40 12.2 10.5 11.4 5.6 50 10 + 20 10 + 40 20 + 20 20 + 40 11.2 9.6 10.3 5.2 75 10 + 20 10 + 40 20 + 20 20 + 40 10.0 8.4 9.0 4.9

Example 5

In the fifth embodiment of the present invention, when placing mass concrete, OPC powders of 1000 to 1200 cm 2 / g of powder collected from the line separated by a cyclone separator during the OPC grinding process and returned to the grinder for the purpose of temperature reduction are OPC. Mix by 10 to 30% by mass relative to the mass of.

Example 6

In the sixth embodiment of the present invention, FA is mixed in the method of the fifth embodiment by 10 to 30% by mass relative to the mass of OPC.

Example 7

In the seventh embodiment of the present invention, the BS of the fifth embodiment is mixed by 20 to 40% by weight of the OPC.

Example 8

In the eighth embodiment of the present invention, FA and BS are mixed in the method of the fifth embodiment by mixing 10-20 mass% + 20-40 mass% relative to the mass of OPC.

Example 9

In the ninth embodiment of the present invention, the experiment of the simulated structure of concrete using low heat cement and 100% OPC composed of OPC 70% + RC 20% + FA 10% in the combination of the fifth embodiment.

The member was made of two square test specimens of 800 mm in width, 800 mm in height, and 800 mm in height, and a temperature sensor (Thermocouple T-Type) was embedded at the top, center, and bottom of the center of the member, and the temperature was measured for 7 days. The results are shown in FIG.

OPC-based concrete showed the highest temperature in the center of about 48 ℃, concrete with low heat generation cement showed about 38 ℃, it was confirmed that the temperature reduction effect of about 10 ℃ compared to the concrete using OPC.

Figure 1 is a schematic diagram showing the grinding process during the manufacturing process of ordinary portland cement.

2, 3, 4, 5 and 6 are particle sizes measured for ordinary portland cement (OPC) as a final finished product of the cement of step A and the cement of step B shown in FIG. It is a graph showing the compressive strength with distribution, powderiness, paste flow, settling time and age.

7 is a graph showing the effect of reducing the heat of hydration temperature according to the present invention by an experiment performed by producing a simulated structure.

Claims (8)

In case of mass concrete placing, 25 ~ 75 mass% of coarse-grained cement with 1500 ~ 2500 cm2 / g of powder collected from the exit of grinding mill during normal portland cement manufacturing process is 75 ~ 25% of the mass of ordinary portland cement. A composition of low calorific cement which lowers the heat of hydration by reducing the hydration reaction by mixing in%. The composition of low heat cement according to claim 1, wherein the fly ash is mixed with 70 to 90 mass% of the low heat cement of the combination method at 30 to 10 mass%. The low calorific cement composition according to claim 1, wherein fine blast furnace slag powder is mixed by 20 to 60% with 80 to 40 mass% of low calorific cement of the combination method. The low heat generation according to claim 1, wherein the low heat generation cement comprises 40 to 70 mass% of fly ash and 20 to 10 mass% of fly ash, and 40 to 20 mass% of blast furnace slag powder. Composition of cement. Collecting the coarse particle powder of 1500 ~ 2500 cm2 / g of the powder discharged from the mill mill during the portland cement grinding process and the coarse particle powder: 25 ~ 75 mass% of ordinary portland cement: 75 And mixing said coarse particle powder with said ordinary portland cement so as to be ˜25 mass%. The method of claim 5, wherein A low calorific cement production method, characterized in that the fly ash is mixed with 30 to 10 mass% of low calorific cement of the combination method. The method of claim 5, wherein A low calorific cement production method characterized by mixing 20 to 60% of blast furnace slag fine powder with 80 to 40 mass% of low calorific cement of said combination method. The method of claim 5, wherein A low calorific cement production method, characterized in that the fly ash is set to 20 to 10 mass% and 40 to 20 mass% of blast furnace slag powder is mixed with 40 to 70 mass% of low heat cement of said combination method.

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