JPH026360A - Lightweight cement composition and production of lightweight cement form therefrom - Google Patents

Abstract

PURPOSE:To efficiently obtain in good formability a lightweight cement form of high mechanical strength through extrusion by using a composition comprising cement, aggregate of specified conditions for giving fluidity, sepiolite and cellulose-based admixture. CONSTITUTION:The objective composition comprising (1) lightweight aggregate 0.1-3mm in mean size, spherical aggregate 1-100mum in mean size and aggregate with pozzolanic action 0.01-1mum in mean size, (2) cement, (3) sepiolite, (4) reinforcing fiber and (5) a cellulose-based admixture. This composition is kneaded with water to produce a plastic kneaded product having bearing effect under pressurized state and thixotropic effect. Thence, this kneaded product is extruded under pressure to obtain a form which is then cured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a lightweight cement molded body and a method for producing a lightweight cement molded body that can advantageously prepare a lightweight cement molded body that is suitably used as a construction member. .

(Prior Art) Light-weight cement molded bodies are used as building materials such as exterior materials, interior materials, and ceiling materials for houses. This type of lightweight cement molded body is, for example, Portland cement,
It is prepared by pouring a cement composition containing lightweight aggregate and water, and optionally other ingredients, into the desired mold and allowing it to harden. The cement molded body is removed from the mold after it has hardened to some extent and is sufficiently hardened, but continuous production is not possible and production efficiency is low.

Therefore, a method of preparing a cement molded body by extrusion molding (dry method) has been adopted.

When obtaining a cement molded body by extrusion molding, it is necessary to improve fluidity in the manufacturing process. Increasing the amount of moisture in a cement composition may be considered to increase its fluidity, but even if the amount of moisture meter is increased, only moisture will flow out before the composition material is extruded by pressure, resulting in poor molding.

Furthermore, even if a molded body with a desired shape is extruded, the shape is distorted and the desired cement molded body cannot be obtained.

Therefore, asbestos has usually been added to the cement compositions used. This asbestos is added for the purpose of increasing the fluidity of the slurry cement composition during the manufacturing process and maintaining the shape of the extruded uncured molded product. Asbestos also plays a role in improving the strength of the resulting cement molded body. However, asbestos is designated as a specified chemical substance, and its carcinogenicity has become a problem.

Although asbestos-cement molded bodies are manufactured using standard materials, molded bodies that do not use asbestos are currently desired due to the problem of dust generation during manufacture and use.

Further, as the lightweight aggregate contained in the above cement composition, pearlite, shirasu balloon, volcanic rubble, etc. with an average particle size of 3 mm or less are used. High external stresses such as shearing, compression, and bending caused by kneading machines and extruders act on such lightweight aggregates. As a result, there is a problem that the lightweight aggregate is crushed, resulting in poor formability, and that the weight of the obtained cement molded product cannot be sufficiently reduced.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional drawbacks, and aims to provide a cement molded product that is easy to extrude, has excellent strength, and is free from harmful An object of the present invention is to provide a lightweight cement composition that does not contain asbestos and a method for producing a lightweight cement molded body.

(Means for Solving the Problems) The lightweight cement l-composition of the present invention comprises cement, lightweight aggregate with an average particle size of 061 to 3M, and an average particle size of l to 100 μm.
Aggregate consisting of spherical particles with an average particle size of 0.01 to 1 μm
It contains an aggregate with a pozzolanic action, sepiolite, reinforcing fibers, and a cellulose-based admixture.

Further, the method for producing a lightweight cement molded body of the present invention includes the steps of obtaining the above-mentioned cement composition, and extruding the plastic kneaded product obtained by kneading the cement composition under pressure, and hardening the molded body obtained. process.

In the present invention, known cements such as Portland cement, blast furnace cement, and alumina cement are used as the cement.

As the lightweight aggregate, lightweight aggregates such as fly ash hollow particles, perlite, shirasu balloons, and volcanic debris are used. The average particle size of such lightweight aggregate is 0.1 to 3 mm. If the average particle size is too small, the lightness and heat insulation properties will be reduced, and if it is too large, the fluidity of the composition will be reduced.

In particular, fly ash emitted from coal-fired power plants
Average particle size 2IIIff1 or less, bulk specific gravity 0.9 or less, preferably average particle size 0.1 to 2ITII11. High specific gravity 0.1
~0.7 hollow particles may be suitably used. Such hollow particles include fly ash with a specific gravity of 35 g, preferably hollow particles suspended in water after elutriation (e.g., CF balloon: Union Chemical Sales, made in China, particle size 2).
Below the fence, the bulk specific gravity is 0.36).

The above lightweight aggregate is 5 to 5 parts by weight per 100 parts by weight of cement.
It is preferably contained in the composition in an amount of 50 parts by weight. If it is too small, the weight and heat insulation properties will be poor, and if it is too large, the strength of the obtained molded product will be reduced.

The aggregate consisting of spherical particles has an average particle size of 1 to 100μ.
It is assumed that m. If the average particle size of this aggregate is too small, there will be little improvement in fluidity during extrusion molding, and if it is too large, the strength of the resulting molded product will be reduced.

As such aggregate, fly ash of pulverized coal combustion ash collected in a dust collector of a coal-fired power plant, spherical calcium silicate, etc. are suitably used.

The above aggregate content is 4 to 80 parts by weight per 100 parts by weight of cement.
It is preferably contained in the composition in parts by weight. If it is too small, the moldability will be poor, and if it is too large, the strength of the obtained molded product will be reduced.

Aggregates with pozzolanic action have an average particle size of 0.01
~1uII+. If the average particle size of this aggregate is too small, the fluidity of the composition will be reduced, and if it is too large, the strength of the resulting molded product will be little improved.

As such aggregate, a high siliceous material is used which has a so-called pozzolan effect, which hardens by combining with lime hydroxide produced during hydration of cement and increases strength. For example, there are ferrosilicon dust, microsilica, silica fume, etc. that are produced as by-products during ferrosilicon (7) 'JA a.

The above aggregate should be added in an amount of 1 to 20 parts by weight per 100 parts by weight of cement.
It is preferably contained in the composition in a proportion of heavy weight. If it is too small, the strength of the obtained molded product will not be improved much, and if it is too large, the moldability will be poor.

Sepiolite contained in the cement composition is, for example, (
011□) 4 (OH), ■gaS! +□0. .・6
It is a magnesium silicate compound shown by ~81120. This sepiolite is a clay mineral with a double-chain structure.
It exists in the form of fibers, powders, granules, plates, etc. Sepiolite exists in either an α-type or a β-type crystal structure, and α-type sepiolite (α-sepiolite), which naturally exists in a fibrous form, is preferably used. The fiber diameter of this fibrous sepiolite is 0.01 to 0.30
μm, preferably about 0.15 μm, fiber length is 2 μm
The thickness is preferably 100 μm or more.

Normally, naturally occurring sepiolite is appropriately pulverized or defibrated by mixing with water and stirring to obtain sepiolite of a desired size (for example, Serpola: Union Chemical Sales, made in China). Sepiolite is added to cement 1 in cement compositions.
00 parts by weight, 3 to 50 parts by weight, preferably 5 to 30 parts by weight
It is contained in 11 parts by weight. If it is too small, moldability will be poor. Furthermore, the density of the resulting cured cement molded body increases, resulting in an increase in overall weight.

Impact resistance also decreases. If it is excessive, the strength of the molded article will decrease.

Reinforcing fibers are used to improve the bending strength and impact strength of the resulting molded product. For example, organic fibers, pulp, metal fibers, etc. are used. As the organic fiber material, alkali-resistant materials such as vinylon, polypropylene, polyethylene, carbon, and aramid are used. The type of pulp is not particularly limited, but waste paper pulp that does not adversely affect the coagulation and hardening of cement is more suitable. The diameter of the reinforcing fibers is 1 to 100 μm, and the fiber length is 3 to 20 mm.
is appropriate. The reinforcing fibers are contained in the composition at a ratio of 0.1 to 10 parts by weight per 100 parts by weight of cement. If the amount of reinforcing fibers is too small, the strength of the resulting molded product will decrease.

If it is in excess, the composition will have poor dispersibility when mixed, resulting in a decrease in the strength of the resulting molded product.

The cellulose admixture is used for the purpose of imparting a certain degree of viscosity and improving fluidity when extrusion molding the composition. As the cellulose-based admixture, methylcellulose, hydroxycellulose, etc. are preferably used. This cellulose-based admixture contains 0 parts by weight of cementum.
．． It is contained in the composition in an amount of 1 to 10 parts by weight, preferably 0.5 to 5 parts by weight. If the amount is too small, the viscosity of the composition will be low, while if it is too large, the viscosity will be high, resulting in poor moldability.

In order to produce a cement molded body by the method of the present invention, a process similar to conventional cement extrusion molding can be adopted. For example, first, the above cement, lightweight aggregate, aggregate made of spherical particles, aggregate having pozzolanic action, sepiolite, reinforcing fibers, and cellulose admixture are triblended.

A suitable amount of water is added to this to perform wet blending, and then thorough kneading is performed using a kneader. The obtained plastic kneaded material is introduced into an extrusion molding machine having a desired mold, and extrusion molding is performed under pressure. The extruded molded product having a desired shape is left to stand for 5 hours or more under predetermined conditions (for example, temperature 10 to 60°C, W degree 80% or more) to dry and solidify. General-purpose equipment is used in all of the above blending process, kneading process, and extrusion molding process.

(Function) When the lightweight cement composition of the present invention is extruded, for example, by the method of the present invention, the kneaded material has sufficient fluidity in the extruder, the flow rate is uniform, and the extruded uncured The molded body has sufficient shape retention until hardening progresses, and crushing of the lightweight aggregate is also prevented.

These good properties are due to the fact that the composition contains aggregate consisting of spherical particles, which exhibits a bearing effect under pressure, and that the kneaded material containing sepiolite exhibits thixotropy (chickentropy). This is thought to be mainly due to the fact that it has good fluidity under pressure and has sufficient shape retention after extrusion.

In addition, since the kneaded material contains a cellulose-based admixture, it is given an appropriate viscosity, and even when molding is performed using a mold with a complex irregular cross-sectional shape, it does not require the conventional dehydration process and can be easily molded. Molding is performed.

Furthermore, the composition contains aggregates that have a pozzolanic effect, and when extruded, this aggregate is densely packed between cement particles, and due to the so-called pozzolanic effect,
The strength of the resulting molded body increases uniformly as a whole. In addition, the obtained molded product contains reinforcing fibers and sepiolite, so it has sufficient strength and impact resistance.

Also, since it contains lightweight aggregate, it is lightweight and has excellent insulation properties.

(Example) Examples of the present invention are shown below.

(A) Preparation of lightweight cement composition Cement (Portland cement) 100% weight lightweight aggregate (CF balloon, average particle size 10 parts by weight 100 μm
Aggregate consisting of spherical particles (fly ash with an average particle size of 5,040 parts by weight μm) Aggregate with pozzolanic action (average particle size of 5 parts by weight 0.5 parts by weight)
15 μm microsilica) Sepiolite (Cervola S-500, 15 fibers overlapped part thickness 0.15 μm, fiber length 100 pm or more)
Reinforcing fiber (vinylon, fiber thickness 12 μm, 1 part by weight fiber length 6 mm) Cellulose admixture (methyl cellulose) 1 part by weight water
48 parts by weight Each component of the lightweight cement composition of the above formulation other than water was placed in a mixer (Eirich Mixer Model RVO2, manufactured by Nippon Eirich Co., Ltd.) and mixed for 2 minutes at 11,000 rpm. Water was added thereto, and the mixture was further mixed for 1 minute, and then sufficiently kneaded with a kneader (auger type extrusion kneader MP-100 model: manufactured by Miyazaki Tekko Co., Ltd.) to obtain a plastic kneaded product.

(B) Manufacture of cement molded product The kneaded material obtained in section (A) is processed using a vacuum extrusion molding machine (vacuum extrusion molding machine MV- FM-^-1 = manufactured by Miyazaki Tekko Co., Ltd.) is supplied to the hopper, and extrusion molded to a width of 25 mm.
A long flat plate sample (uncured molded body) with 0 weight and a thickness of 15 mm was prepared.

The extrusion pressure and extrusion amount per unit time at this time were measured. The extrusion pressure was measured by measuring the pressure in the resistance section from the barrel of the extruder to the mold using a Bourdon tube pressure gauge. The amount of extrusion per unit time was expressed as the volume of the flat sample extruded from the tip of the mold.

After leaving this uncured molded body at room temperature for 5 hours (pre-curing), it was heated for 12 hours at 50°C in an atmosphere of 95% or more RH.
It took time to heal. This flat plate molded body was placed in water at 20°C for about 4 hours.
After soaking for a week, cut into pieces of medium 25 mm and length 240 mm (
The sample was cut perpendicularly to the extrusion direction), placed in a gear oven at 105°C, dried for about 48 hours, and then allowed to cool for 24 hours.

This sample was supported at intervals of 200 mm, and the bending strength was measured by applying force to the center at a bending speed of 2.5 mm/min.

In addition, cure and harden in the same manner as above, and make a 200mm x 20
0111 [Create 11 samples and heat them to 105°C
After drying for about 48 hours in a gear oven, it was left to cool for 24 hours. The specific gravity of this sample was measured. The above results are shown in Table 1.

The same procedure as in Example 1 was carried out except that the formulation of the lightweight cement composition was changed as shown in Table 1.

The results are shown in Table 1.

Margins below (Effects of the Invention) As described above, according to the present invention, a lightweight cement molded body with excellent strength can be obtained by extrusion molding with good moldability and high efficiency. Such lightweight cement molded bodies are suitably used, for example, as exterior materials, interior materials, and ceiling materials for houses. Moreover, since it does not contain asbestos, there is no risk of carcinogenesis due to asbestos dust generation either during the manufacturing process or during use.

Claims (1)

[Claims] 1. An aggregate consisting of cement, lightweight aggregate with an average particle size of 0.1 to 3 mm, and spherical particles with an average particle size of 1 to 100 μm;
A lightweight cement composition containing pozzolanic aggregate with an average particle size of 0.01 to 1 μm, sepiolite, reinforcing fibers, and a cellulose admixture. 2. Obtaining the lightweight cement composition according to claim 1;
A method for producing a lightweight cement molded body, which includes the steps of extruding a plastic kneaded product obtained by kneading this cement composition under pressure and curing the resulting molded product.