JPH0525827B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field] The present invention relates to hydraulic compositions used in a wide range of applications as roofing materials, exterior wall materials, interior wall materials, flooring materials, ceiling materials, and exterior building materials such as gates and fences, and particularly relates to hydraulic compositions that are produced in large quantities during steel manufacturing. The main component is granulated blast furnace slag, which by itself does not have high strength, takes a long time to harden, and suffers from large curing shrinkage. , has impact strength,
Further, the present invention relates to a hydraulic composition that has low efflorescence and dimensional shrinkage (dimensional change) rate, has significantly improved cracking, and has excellent moldability and formability in extrusion molding, compression molding, etc. [Background technology] In recent years, there has been a marked increase in the use of dry construction methods for ceramic moldings, especially building materials.For this purpose, ordinary Portland cement, white cement, or a portion of Portland cement is replaced with granulated blast furnace slag It is common to provide molded products by kneading, shaping, and hydration hardening (curing hardening) using so-called blast furnace cement or the like substituted with water.
However, it has not been possible to economically produce a hydration-hardened material with a high enough strength to withstand actual use by using a hydraulic composition that uses 70% by weight or more of blast furnace slag, which is a by-product of blast furnaces during steel manufacturing. The current situation is that this is not the case. In other words, common industrial production methods include portland cement (including white cement), normal hydraulic cement such as blast furnace cement,
Alternatively, inorganic fillers such as fly ash, silica sand, and shirasu are added to quick-hardening cement such as jet cement, and asbestos, which has become a sanitary problem in recent years, is added, and if necessary, kneading, processability, and shape retention are improved. To improve this, a small amount of organic polymer additive is added, mixed and kneaded with an appropriate amount of water to prepare a hydraulic composition, this hydraulic composition is shaped into a predetermined mold, and cured. The cured product is created by Also, regarding this curing, although a hardened product can be obtained by means such as natural curing or steam curing, it takes a long time to develop strength, and the strength is at most 250 to 300 kg/cm ²
It has only a bending strength of . In addition, high-temperature, high-pressure curing using an autoclave is also commonly performed, but curing requires a large amount of thermal energy, making it uneconomical, and the strength of the resulting cured product is no different from the former. . [Objective of the Invention] The present invention has been made in view of the above-mentioned points, and uses granulated blast furnace slag with a high blending amount, which has not been practically available up to now, and is capable of being cured at high temperature and high pressure using autoclave or other methods. To provide a hydraulic composition that can economically obtain a hydraulically cured product having high strength, especially high bending strength, that can withstand permanent use by natural curing or steam curing, etc., without any dry curing. The purpose is to realize energy saving, resource saving, and weight reduction, and to contribute to the development of ceramic materials. [Disclosure of the Invention] That is, the hydraulic composition of the present invention contains 70% by weight or more of granulated blast furnace slag and 1.5% by weight of dihydrate gypsum and calcium aluminate monosulfate hydrate.
~15% by weight of a water-soluble organic high It is characterized by containing 3 to 15 parts by weight of molecular substances, including granulated blast furnace slag and calcium aluminate monosulfate hydrate; 3CaO.
Blend Al ₂ O ₃ .CaSO ₄ .12H ₂ O (hereinafter referred to as MSH) and dihydrate, and add to this a hydrolyzate of polyvinyl acetate and/or its copolymer, pullulan, hydroxypropyl methylcellulose, etc. By allowing a water-soluble organic polymer substance to coexist, at the initial stage of the hydration reaction, the reaction between MSH and dihydrate produces calcium aluminate trisulfate hydrate;
Dense acicular crystals of 3CaO.Al ₂ O ₃ .3CaSO ₄ .31~32H ₂ O (hereinafter referred to as TSH) are deposited between particles and on the surface of granulated blast furnace slag through a solution of a highly viscous water-soluble substance. The above object is achieved by promoting the hydration of the blast furnace slag and forming a mutually strong and dense hardened body. The present invention will be described in detail below based on examples. In a hydraulic composition mainly composed of granulated blast furnace slag, calcium aluminate monosulfate hydrate; 3CaO.Al ₂ O ₃ .CaSO ₄ .12H ₂ O (hereinafter referred to as
MSH) and dihydrate gypsum are essential components, and a water-soluble organic polymer substance is added to water to a hydraulic cement composition consisting of these three components, and the hydraulic composition obtained by mixing these components is kneaded to form a predetermined mixture. By forming and hardening it into a mold, we have created a hydraulically hardened material that has high bending strength and impact strength that cannot be obtained with conventional Portland cement, blast furnace cement, etc., and also does not suffer from shrinkage cracks, which are the drawbacks of blast furnace slag. It's something you get. In the present invention, granulated blast furnace slag is applied to granulated blast furnace slag, which is obtained by pulverizing slag by-produced from a blast furnace in a steel mill and is a component of hydraulic cement, which is usually commercially available as blast furnace cement. When obtaining a hardened body using granulated blast furnace slag, it is common to add 30 parts by weight or more of Portland cement; when obtaining a high-strength hardened body using this granulated blast furnace slag, It is common practice to add inorganic or organic fibrous substances such as asbestos, glass fiber, bulb, vinylon, polypropylene, etc., and to reduce the amount of mixed water as much as possible by using water reducing agents, etc. Even in a cured product obtained by mixing and kneading, shaping into a predetermined mold, and curing and curing, for example, when looking at the bending strength, it is extremely rare for the bending strength to exceed 300 Kg/cm ² according to the experience of the present inventors. Based on this technical background, the present inventor uses 70% by weight or more of granulated blast furnace slag in a hydraulic cement composition in order to obtain a hydraulic hardened body having a high bending strength of 400 Kg/cm ² or more. It provides the conditions for In order to effectively harden granulated blast furnace slag, a suitable hydration stimulant is required, and it is known that, for example, calcium hydroxide, calcium chloride, sodium carbonate, etc. are effective. However, even if these stimulants are used, it is insufficient to develop the strength of the hydrated and hardened material of granulated blast furnace slag, and it is difficult to suppress the occurrence of cracks due to hardening shrinkage, which is a major drawback of blast furnace slag. Therefore, it could not be an effective means of utilizing resources. In view of the above circumstances, the present inventors investigated effective hardening accelerators for granulated blast furnace slag and additives that contribute to improving strength. Initially, crystals of ettringite, which is effective for developing strength, are formed between particles of granulated blast furnace slag by the reaction between MSH and dihydrate gypsum, and then a dense hydrated slag is formed to form TSH. They have discovered that forming the material into a shape that includes it is extremely effective in developing early strength, curing shrinkage, and preventing cracks.
In addition, in order to obtain a high-strength hardened product by kneading and shaping a hydraulic composition mainly composed of granulated blast furnace slag, a water-soluble organic polymer substance is added in the presence of MSH and dihydrate gypsum. It is effective to add
It dissolves or swells at temperatures below 100°C. In addition, it is necessary that the material forms a strong film that is insoluble or sparingly soluble in water as hydration progresses and dries. For this purpose, suitable polymers that can be used as water-soluble and water-swellable organic polymer substances effective in improving strength in the hydraulic composition of the present invention include polyvinyl acetate and/or copolymers thereof. hydrolyzate of polymer (polyvinyl alcohol or its copolymer; PVA), pullulan (a linear comparative product in which maltotriose with α-1,4-bonds is repeatedly polymerized with α-1,6-bonds at both ends) hydroxypropyl methylcellulose is preferred. Among them, hydrolysates of polyvinyl acetate and copolymers thereof are highly curing even when added in relatively small amounts. however,
Portland cement, white cement, blast furnace cement, jet cement, etc. contain calcium (Ca ⁺⁺ ) that precipitates even at the very beginning of the hydration reaction.
is combined with the above-mentioned PVA or its copolymer and pullulan to produce a water-insoluble gel-like substance, and cannot form a kneaded material with viscoelasticity suitable for molding processability, except for extremely dilute PVA solutions. This makes it impossible to mix it into hydraulic cement. On the other hand, there have been attempts to add quicklime or slaked lime to granulated blast furnace slag as a hydration reaction stimulant, but in this case, even if a dense hardened product could be made, the bending strength was only about 200 kg/ ^cm2 ; Furthermore, when water-soluble organic polymer substances such as PVA, which are effective in hydraulic substances such as granulated blast furnace slag, MSH, and dihydrate gypsum, are added to the granulated blast furnace slag, quicklime, or slaked lime system,
The reaction between Ca ⁺⁺ and PVA only forms a sand-like substance with no viscosity, and a kneaded material that can be used for molding cannot be obtained. In view of the above circumstances, the present inventor has conducted intensive research to effectively harden blast furnace slag and obtain a hydraulic composition with a dense composition and high bending strength. By blending polyvinyl acetate and/or its copolymer hydrolyzate, pullulan, hydroxypropyl methylcellulose, and other water-soluble organic polymer substances, MSH can be added at the initial stage of the hydration reaction. The reaction between gypsum and gypsum promotes the formation of dense acicular crystals of TSH between particles and on the surface of granulated blast furnace slag through a solution of highly viscous water-soluble substances, and then this product is transferred to the blast furnace. It has been found that hydration of the slag is promoted to form a mutually strong and dense hardened body. In this way, by adding MSH and gypsum together to granulated blast furnace slag, even when water-soluble organic polymer substances such as PVA, which normally cause gelation in the presence of Ca ⁺⁺ , are added, no sand-like particles can be formed. It is possible to obtain a kneaded product with excellent lubricity and viscoelasticity without forming any pores, and the strength of the molded and cured product has been surprisingly high, with a bending strength of 600 kg/cm ² or more.
That is, during hydration, the influence of Ca ⁺⁺ is
It contributes to making PVA water-resistant and insolubilizable, and as the reaction progresses, the bonds between tissues become denser and stronger due to the production of TSH. In general, it is effective in developing the strength of hardened hydraulic cement.
Regarding TSH, the lower the water/cement ratio is, the more difficult it is for TSH crystal formation to occur, and even in hydraulic cement that easily generates TSH, such as ordinary Portland cement, when the water/cement ratio is less than 0.25, TSH crystal formation is less likely to occur. It has been reported that it is extremely small. However, by pre-adding MSH and gypsum dihydrate as essential components of a hydraulic composition, TSH is generated even in a low mixed area with a water/cement ratio of 0.15, which is extremely effective in developing strength and reducing curing shrinkage. It is something. However, even if TSH is added to a hydraulic composition, it is not effective for developing strength or promoting hydration of granulated blast furnace slag. These matters are particularly important in determining the weight ratio of MSH and dihydrate gypsum and their blending amount, which are applied to the present invention, in order to secure various substances. Here, the blending amount of MSH and dihydrate is 1.5 to 15% by weight with respect to the hydraulic cement composition consisting of granulated blast furnace slag, dihydrate gypsum, and MSH, and if it is less than 1.5% by weight, the initial It takes time to develop strength, and it is not possible to prevent cracks caused by hardening shrinkage, which is a drawback of granulated blast furnace slag. Conversely, if the amount of MSH and gypsum exceeds 15% by weight, there is a risk of swelling cracks in the hydraulic composition, and even water-soluble polymeric substances, especially polyvinyl acetate hydrolyzate (PVA). ,
It promotes the gelation of pullulan, and the kneaded product loses its viscosity and swelling properties in a short period of time, making it impossible to mold it.
The mixing ratio of MSH/gypsum dihydrate needs to be 1/0.55 (1.8) to 1/5 (0.2) by weight, preferably 1/1 (1.0).
If the ratio of MSH/gypsum dihydrate exceeds 1/0.55 (1.8), unreacted MSH will remain, causing problems in final durability;
If it is less than 10%, water resistance will be impaired due to excess gypsum. Further, in order to stimulate and promote the hydration of granulated blast furnace slag, known hydration reaction stimulants such as calcium chloride, sodium carbonate, sodium acetate, calcium acetate, etc. can be used. However, if MSH and dihydrate gypsum are not included, and if polyvinyl acetate hydrolyzate (PVA) is not included, and if a hardening stimulant such as calcium chloride is added for hardening, blast furnace slag Not only does the curing time vary widely depending on the lot, but it also causes undesirable results such as cracks in the cured product. The hydrolyzate (PVA) of polyvinyl acetate or (and) its copolymer used as a water-soluble organic polymer substance has a saponification degree of
It is possible to use 2.5 to 15 parts by weight of 65 to 99.5 mol%, preferably 75 to 90 mol%.
In this case, PVA having two or more saponification degree modes with different water dissolution rates and water dissolution viscosities may be used. Hydroxypropyl methylcellulose, pullulan, etc. used as other water-soluble organic polymer substances should be used in the range of 0.3 to 2.5 parts for shape retention.
Desirable from the viewpoint of curing balance. The present invention uses water-soluble organic polymer substances such as MSH, gypsum dihydrate, and PVA as essential ingredients and hydration reaction stimulators as necessary to the granulated blast furnace slag to produce calcium chloride, sodium carbonate, sodium acetate, and calcium acetate. Depending on the purpose of use, asbestos,
glass fiber, wollastonite, valve,
Inorganic materials such as vinylon, nylon, polypropylene, etc.
Fillers such as organic fibers, silica sand, shirasu, mica, fly ash, clay, and calcium carbonate are blended, and 15 parts by weight or more and 35 parts by weight or less of water are added and kneaded, followed by extrusion molding, compression molding, or transfer molding. This refers to a hydraulic composition that can be shape-cured by shape-curing, and can easily and inexpensively provide cured molded products with complex irregular cross-sections, including flat plates and hollow spaces, and can be used for roofing materials, exterior wall materials, and interior walls. It can be used in a wide range of applications as exterior building materials such as wood, flooring, ceiling materials, gates, and fences. The present invention will be explained below based on examples. Examples 1 to 4, Comparative Examples 1 to 4 As shown in Table 1, granulated blast furnace slag and MSH
and dihydrate gypsum to make 100 parts by weight of the hydraulic cement composition. and) 5 parts by weight of the hydrolyzate of the copolymer (PVA) and 0.5 parts by weight of pullulan are added and mixed. Next,
Calcium chloride prepared in advance and cooled to room temperature
Add 18.5 parts by weight of a 10% aqueous solution to the above mixture in a pressure kneader and knead under pressure for 2.5 minutes to obtain a viscoelastic kneaded product. This kneaded material is generally called dough. Next, this dough was put into a hopper of an extrusion molding machine equipped with a vacuum degassing device, and a continuous plate-like sample having a thickness of 6 mm and a width of 60 mm was molded while being vacuum degassed. The extrusion pressure was 50-60 Kg/ ^cm2 . Next, this molded product is sealed with a polyethylene sheet,
After leaving it at room temperature (25℃) for 15 hours, it will remain sealed for 60 hours.
Moist heat curing was performed for 40 hours in a constant temperature bath at ℃, and the sample was left in a humid air condition for 4 weeks. Next, this sample was dried at 60° C. for 15 hours and used as a sample for dry strength measurement. The strength was determined by bending strength (3-point bending test) and Sialby impact strength. In addition, to check water resistance, a sample prepared by the above treatment was immersed in water for 15 hours, the adhering water was wiped off, and the sample was air-dried for 3 hours to determine the bending strength, which was taken as the hygroscopic strength. The results are shown in Table 1. Comparative Example 1 could not be molded, Comparative Example 2 had delayed curing, Comparative Example 3 had poor water resistance, and Comparative Example 4 cracked. In addition, as confirmed by X-ray diffraction, the formation of ettringite was observed from 10 hours after molding when MSH and dihydrate gypsum were mixed, and after moist heat curing at 60℃.
All MSH seems to react with gypsum to generate TSH. In other words, in the low water mixing region where the water/cement ratio is 0.2 or less, the formation and growth of TSH crystals is not normally observed, but with the addition of MSH, dihydrate gypsum, and PVA, they are easily formed, and in the process, water granulation occurs. The stimulation of hydration of blast furnace slag is adjusted to form a dense hardened body, which greatly contributes to the initial and final strength development. On the other hand, in Comparative Examples 1, 2, and 4, no TSH was grown, and in Comparative Example 3, the water resistance of the cured product decreased due to the residual unreacted gypsum. Examples 5 to 11, Comparative Examples 5 and 6 4 parts by weight of dihydrate were added to 95 parts by weight of granulated blast furnace slag, 1 part by weight of MSH, and the total amount was 100 parts by weight of the hydraulic cement composition. To this, the parts shown in Table 2 such as polyvinyl acetate hydrolyzate (PVA), hydroxypropyl methyl cellulose, pullulan, etc. are added and mixed. Next, 18.5 parts by weight of a 10% calcium chloride aqueous solution, which had been prepared in advance and cooled to room temperature, was added to the above mixture in a pressure kneader and kneaded under pressure for 2.5 minutes to obtain a viscoelastic kneaded dough. . Next, this dough was put into a hopper of an extrusion molding machine equipped with a vacuum degassing device, and a continuous plate-like sample having a thickness of 6 mm and a width of 60 mm was molded while being vacuum degassed. The appearance of the obtained molded product was uniform and smooth, and the extrusion pressure was 50 to 65 kg/cm ² . Next, this molded product was sealed with a polyethylene sheet and left at room temperature (25°C) for 15 hours, and then kept sealed in a thermostat at 60°C for 40 hours with moist heat curing.
It was left in a humid air condition for 4 weeks. Next, add this sample to 60
The sample dried at ℃ for 15 hours was used as a sample for dry strength measurement. The strength was determined by bending strength (3-point bending test) and Sialby impact strength. In addition, to check the water resistance, a sample prepared by the above treatment was immersed in water for 15 hours, the adhering water was wiped off, and the sample was air-dried for 3 hours to determine the bending strength, which was taken as the wet strength. The results are shown in Table 2. Note that Comparative Example 6 was inferior in water resistance.

【table】

[Table] [Effects of the invention] As described above, the present invention contains 70% by weight or more of granulated blast furnace slag, 1.5 to 15% by weight of dihydrate gypsum and MSH, and the blending ratio of MSH and dihydrate gypsum is 1. :0.5～
Since 3 to 15 parts by weight of a water-soluble organic polymer substance is blended in 100 parts by weight of a hydraulic cement composition with a ratio of 1:5, the hydraulic composition is prepared using a high blending amount of granulated blast furnace slag. By using the four components of granulated blast furnace slag, gypsum dihydrate, calcium aluminate monosulfate hydrate, and a water-soluble organic polymer substance in the above-mentioned combination, it is possible to The reaction between MSH and dihydrate gypsum promotes the formation of dense acicular crystals of TSH between particles and on the surface of granulated blast furnace slag through a solution of a highly viscous water-soluble organic polymer substance, and then This product promotes the hydration of blast furnace slag to form a mutually strong hardened product, which has a high strength that can withstand permanent use through natural curing or steam curing without the need for high-temperature and high-pressure curing such as in an autoclave. , it is possible to obtain a hydraulically cured body having especially high bending strength in a short period of time and economically.

Claims (1)

[Claims] 1. 70% by weight or more of granulated blast furnace slag, 1.5 to 15% by weight of dihydrate gypsum and calcium aluminate monosulfate hydrate, calcium aluminate monosulfate hydrate and dihydrate gypsum. A hydraulic cement composition characterized in that 3 to 15 parts by weight of a water-soluble organic polymer substance is blended to 100 parts by weight of a hydraulic cement composition having a mixing ratio of 1:0.5 to 1:5 by weight. Composition. 2. A patent characterized in that the water-soluble organic polymer substance consists of at least one selected from the group consisting of a hydrolyzate of polyvinyl acetate, a hydrolyzate of polyvinyl acetate copolymer, pullulan, and hydroxypropyl methylcellulose. The hydraulic composition according to claim 1.