JPH0346390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precast member for making cylindrical silos such as grain silos, cement silos, and aggregate silos. It is composed of cast concrete, precast concrete, steel, etc. However, in the case of concrete silos, the bending and tensile strength of the hardened cement material used as the precast member is low, so the member needs to be thicker, resulting in excessive weight and being prone to cracking. Furthermore, there was a problem that the bonding between the precast members was not sufficiently tight. Additionally, steel silos have the problem of being susceptible to rust and corrosion.

The present invention was made in view of the above circumstances, and
It is an object of the present invention to provide a precast member for a cylindrical silo, which is lightweight by increasing the strength of the cured body, and which allows easy and sufficiently tight bonding between the precast members.

In the present invention, 100 parts by weight of at least one type of hydraulic cement, 10 to 25 parts by weight of water, and 0.1 to 10.0 parts by weight of at least one type of processing additive are mixed under high shear, and the resulting mixture is A precast member made of a hardened cement material having a bending strength of 50 MPa or more and a Young's modulus of 30 GPa or more formed by vibration compaction molding, the hydraulic cement comprising:
The precast member has a multi-mode particle size distribution with particle size peaks on at least the fine particle side and the coarse particle side, respectively, and the precast member has a curvature so as to form a part of a cylinder, and has a pair of opposing end edges. The precast member is formed into a substantially rectangular plate having a side view, and one of the end edges of the precast member is convex so that when a plurality of the precast members are placed adjacent to each other, they fit tightly together. The means for achieving the above object is that one of the side surfaces is formed in a convex shape and the other side is formed in a concave shape. According to the present invention, by making the hydraulic cement have a multi-mode particle size distribution, the packing density between the cement particles and between the cement particles and the processing additives is increased, and the resulting hardened product is increased. A processing additive that can improve strength (flexural strength, Young's modulus) and also provides lubricating action, dispersion action, or plasticizing properties to cement particles, and the above-mentioned hydraulic cement and water are mixed under high shear. By vibrating and compacting the resulting mixture, the bending strength is over 50 MPa,
It becomes an extremely high-strength hardened cement product with a Young's modulus of 30GPa or more.

Furthermore, since it is formed to have a curvature to form a part of a cylinder, and one side of the side is convex and the other side is concave, adjacent members fit tightly together. match.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 are diagrams showing one embodiment of the precast member of the present invention. The precast member 1 shown in these figures is formed into a plate having a substantially rectangular curvature and is made of hardened cement. Among the vertically opposing edge portions 2 and 3 of the precast member 1, one edge portion 2 is formed with a convex portion 2a, and the other edge portion 3 is formed with a concave portion 3a.
is formed. In this case, the convex portion 2a is formed at the center of the edge portion 2, and its width _d1 is 1/3 of the width D of the precast member 1. Further, a concave portion 3a is also formed at the center of the edge portion 3, and its width _d2 is 1/1/2 of the width D of the precast member 1.
It has become 3. Further, the length l ₁ of the convex portion 2a and the length l ₂ of the concave portion 3a are formed to be equal.
As shown in FIG. 3, the precast member 1 is formed with a predetermined curvature so as to form a part of the circumference of a cylindrical silo.

Further, the side surface of the outer peripheral edge of the precast member 1 has a convex surface and a concave surface so that adjacent precast members fit tightly into each other when the silo is assembled. In this example,
Two types of precast members are formed in which the arrangement of the convex and concave surfaces on the outer peripheral surface of the precast member is different. That is, as shown in FIGS. 2a and 2b, when the convex parts 2a and 2a are placed facing in opposite directions, the surfaces to be fitted together (surface 4 in FIG. 2a and surface 5 in FIG. 2b) ), one side is convex and the other side is concave. Similarly, other parts of the side surfaces of the outer peripheral edges of the precast members 1, 1 are also formed into convex surfaces, so that the two types of precast members shown in FIGS. 2a and 2b can be combined and tightly fitted together. It's becoming like that. In addition, in Fig. 2 a and b, the convex portion is marked with the symbol A.
The concave portion is marked with B.

In addition, in the above embodiment, an example in which one convex part 2a and one concave part 3a are formed on the edge parts 2 and 3 is explained, and the widths d ₁ and d _{2 of the convex part 2 a and the concave part 3} a are 1/ of the width D of the precast part
3 has been described, but the present invention is not limited to the above shape.

Next, a method for manufacturing the precast member 1 will be explained.

The precast member 1 contains 100 parts by weight of at least one type of hydraulic cement, 10 to 25 parts by weight of water,
It is formed by high shear mixing with 0.1 to 10.0 parts by weight of at least one processing additive, and then placing the resulting mixture in a mold and subjecting it to vibratory compaction.

To explain in more detail, the hydraulic cement includes ordinary Portland cement, early-strength Portland cement, sulfate-resistant cement, ultra-rapid hardening cement, etc., which are generally classified as Portland cement, aluminum cement, high aluminum cement,
Calcium aluminate cement, blast furnace cement,
Fly ash cement, silica cement, gypsum, etc. can be used, and at least one type of hydraulic cement selected from these cements may be added, as well as a small amount of an additive for accelerating or retarding curing.

In addition, in order to obtain high strength, especially high bending strength, the hydraulic cement has a particle size distribution (or a combination of particle size distributions) that is a combination of fine cement and coarse cement, and one with an intermediate particle size. The multimode mode excluding
By using such multiple modes, the filling state between the cement particles becomes extremely dense. Furthermore, fine particles of 0.05μ or less (for example,
fine particles of cement, silicic acid, carbon black, etc.)
It is desirable to add a small amount of to obtain high strength.

In addition, the processing agent is one that imparts a lubricating effect, a dispersing effect, or a plasticizing property to the cement particles, and includes, for example, oxypropyl methylcellulose, acrylamide polymer or copolymer, polyalkylene glycol ( Molecular weight approx.
10,000 or more), sulfonated naphthalene salts, hydroxypropyl methylcellulose (HPMC), etc. The average molecular weight of the processing additive is
Preferably greater than 10000.

The above-mentioned hydraulic cement, water, and processing additives are mixed using a Banbury mixer, twin roll mill, or the like, and high shear mixing is performed. Preliminary mixing may be performed using a mixing roll or the like as a pre-stage of this high shear mixing.

When forming the above mixture, the porosity of the resulting cured product must be 20% or less, preferably 10% or less, and the maximum pore size must be 10μ or less, preferably more than 15μ. must be 2% or less. Satisfying this condition,
Mixture (dough) obtained by the above high shear mixing
To form the material, it is placed on a press molding machine equipped with the desired frame, vibrated and compacted under a predetermined pressure, and then molded.

The molded product is cured, for example, in a polyethylene bag for 24 hours, then cured in humid air for the required time (for example, 7 days) in a foggy room with a humidity of 95% or more, and finally cured in an atmosphere with a relative humidity of 45 to 55% and a humidity of 20°C. By drying the material for 10 days or more, a precast member as a product can be obtained.

The precast member formed as described above can be given high strength such as a bending strength of 50 MPa or more and a Young's modulus of 30 GPa or more. Therefore, the precast member according to the present invention can exhibit sufficient strength even when the thickness is reduced.

Next, a case will be described in which a cylindrical silo is created using the above precast member.

The above precast members are shown in Fig. 2 a, b, Fig.
As shown in the figure, a silo can be formed using a predetermined number of two types of shapes. That is, the precast members 1, ₁ , . A stage with a similar arrangement is formed with a shift of /3). The vertically adjacent precast members 1, 1 are tightly coupled by fitting the rectangular wave-like irregularities formed by the respective convex portions 2a and concave portions 3a into each other. In addition, between the precast members that are adjacent to each other in the upper and lower directions and the left and right sides, the convex and concave surfaces of the side surfaces of the outer peripheral edge portions are tightly fitted to maintain airtightness and strength. Then, tightening members 6, 6, 6 made of high tensile strength round steel are wound around the fitting portions of the convex portions 2a, 2a, . . . and the concave portions 3a, 3a, .
Tightened by 7,7.

The cylindrical silo formed in this way has sufficiently high strength because the precast member is made of multi-mode hydraulic cement as described above, so its thickness can be reduced. However, the required strength can be obtained even if the material is not used, and this results in a product that has the same strength and is lighter than conventional products. In addition, between adjacent precast members,
Since the precast member is formed with a curvature so as to form a part of the cylindrical body, the convex surface and the concave surface on the side surface of the outer peripheral edge are tightly fitted into each other, thereby improving airtightness and strength. High silos can be built. Furthermore, during construction, since each precast member is lightweight, transportation, assembly, etc. are easy, and work efficiency can be improved.

Note that the tightening of the outer circumferential surface of a silo constructed from precast members is not limited to the use of the tightening members 6 and rods 7 shown in the above embodiment, but as shown in FIG. Attachment member 10
This may be fixed to the precast member using bolts 11, 11, . . . . Additionally, a waterproof paint or the like may be applied to the inner surface of the silo to improve airtightness.

Next, the present invention will be specifically explained with reference to experimental examples.

〔Example〕

Special fine powder cement (trade name: colloidal cement, average particle size approximately 8μ) and coarse powder Portland cement (particle size range 76 to 125μ) in a weight ratio of 1:4.
A premix of hydraulic cement was prepared. To 100 parts by weight of this premix, 4 parts by weight of a polyacrylamide-containing aqueous solution and a polyalkylaryl sulfonate were added as a plasticizer and a water reducing agent in terms of solids, so that the water-cement ratio was
It was adjusted to 17.5% and mixed in a twin roll mill. This mixture was applied to a vibrating pressure compaction machine to obtain a precast member having the shape shown in FIG. The thickness of the precast member was 20 mm. Also, at the same time, use the same mixture to separate 20mm
A thick specimen was prepared, and the precast member and the specimen were left to dry for 14 days in a humid atmosphere at 22° C. and a humidity of 95% or more. When a bending fracture test was conducted on the joint specimen, a bending strength of 60±3 MPa was obtained.

As explained above in detail, the precast member for a cylindrical silo of the present invention has a multi-mode particle size distribution of hydraulic cement, which improves the packing density between cement particles and between them and processing additives. In addition to improving the strength (flexural strength, Young's modulus) of the resulting hardened product, processing additives provide lubricating, dispersing, or plasticizing properties to cement particles, and the hydraulic properties. Cement and water are mixed at high shear, and the resulting mixture is subjected to vibration compaction molding to improve the strength (flexural strength, Young's modulus) of the hardened product, so it is different from conventional products. By keeping the strength to the same level, the thickness can be reduced, and the weight can therefore be reduced.
This can improve workability during silo construction.

In addition, it is formed to have a curvature to form a part of the cylinder, and one side of the cylinder is formed into a convex shape and the other side is formed into a concave shape, so that adjacent members can be tightly fitted together. As a result, it is possible to construct a silo with high airtightness and strength. Further, since the precast member of the present invention is made of a hardened cement body, a cylindrical silo made using the same has advantages such as high durability.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the precast member according to the present invention, FIGS. 2a and b are perspective views for explaining the shape of the precast member, and FIG. 3 is a plan view showing an embodiment of the precast member according to the present invention. FIG. 4 is an explanatory view showing a state in which the members are fitted together, and FIG. 4 is an explanatory view showing another example of a method of tightening between precast members. 1... Precast member, 2, 3... Edge portion,
2a...Convex portion, 3a...Concave portion, A...Convex surface,
B... Concave.

Claims (1)

[Claims] 1. A compound obtained by high-shear mixing of 100 parts by weight of at least one type of hydraulic cement, 10 to 25 parts by weight of water, and 0.1 to 10.0 parts by weight of at least one type of processing additive. Bending strength of 50 MPa or more and Young's modulus of 30 GPa formed by vibration compaction molding of the mixture
A precast member made of the above hardened cement body, wherein the hydraulic cement has a multi-mode particle size distribution with particle size peaks at least on the fine grain side and the coarse grain side, and the precast member has a cylindrical shape. The precast member is formed into a substantially rectangular plate body having a curvature to form a part of the precast member and a pair of opposing end edges and side faces, and when a plurality of the precast members are placed adjacent to each other, One of the end edges of the precast member is formed in a convex shape and the other is formed in a concave shape, and one of the side surfaces is formed in a convex shape and the other side is formed in a concave shape so as to fit into the precast member. A precast member for cylindrical silos, which is characterized by: