JPS61191551A - Manufacture of cementitious cured body - 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] (Technical field) The present invention relates to a method for producing a cement-based hardened body.

(Background Art) Recently, much research has been carried out on making cement-based hardened bodies denser and stronger, and among them, research by Imperial Chemical Industries (ICI) is famous. In addition, A company is also conducting research on making Danish oars denser. Published by ICI Co., Ltd. in 1987
In Publication No. 129853, a vinyl acetate polymer having a degree of saponification of 70 to 90% is used as cement.

This product is fully applicable to cements with low pH such as slag and alumina cement, but with cements with high P)I such as Portland cement, saponification by alkali progresses and the resin becomes molten, resulting in extrusion molding, etc. It is difficult. Additionally, Denmark's Allgere adds a high-performance water reducing agent (Mighty), and it is mainly used for casting, so its viscosity is low and it is unsuitable for extrusion molding. However, extrusion molding is attracting attention as a method that can produce uniform products continuously, and vinyl acetate polymer systems are currently attracting attention as binders because they offer higher strength than methyl cellulose.

(Objective of the Invention) The present invention has been proposed in view of the above-mentioned current situation, and its object is to provide a method for producing a highly dense and high-strength hardened cement body.

(Disclosure of the Invention) The present invention relates to manufacturing a highly dense and high-strength cement hardened body by extrusion molding a cement hardened body containing portland cement as a hydraulic substance, It is characterized by using a vinyl acetate polymer as a binder.

I￥1″ vinyl-based vinyl polymer silicide product has a pH of 1.
When it is 2.5 or more, saponification is promoted and dulling progresses. As there are 11 units for alumina cement slag d and PH, the progress of delification is slow, but for Portland cement, Pf
(Since it reaches 125 or more, even around 13, gluing progresses rapidly, and when used for extrusion molding, etc., it quickly loses viscosity and cannot be molded.)

By adding amorphous silica, it reacts with the alkali released from Portland cement and prevents the pH of the system from increasing, thereby delaying the progress of gluing. This effect is greater as the particle size becomes finer. Therefore, by adding amorphous silica to secure the time required for extrusion molding,
It can be extruded and produces a highly dense and strong hardened cement product.

The raw materials used in the present invention are as follows.

As the cement, use is made of a system in which Portland cement contains a hydraulic substance in an amount of 10 or more by weight.

As a filler, the weight ratio of amorphous silica is 10 or more (if it is less than this, it is difficult to secure time), and the particle size of the amorphous silica is preferably 10 μm or less on average.
It is better to be below RL. If it is large, the 4727 reactivity will be small and the effect will be small. Further, other fillers and reinforcing fibers may be added. Please note that there are no particular restrictions on water mixing ratio, curing conditions, etc. (
The vinyl acetate polymer should be water-soluble and have a degree of saponification of 60% or more, preferably 70% or more and 90% or less. Further, the degree of polymerization is preferably 1000 or more.

The addition amount is preferably 1% or more by weight, preferably 2% or more and IO% or less. If it is less than 1%, extrusion molding will be difficult, and if it is more than 10%, there is a risk that the water use of cement will be inhibited.

Furthermore, by adding polyamide-epoxy modified resin to the system consisting of Portland cement, vinyl butyrate resin, and amorphous silica, the time for which the viscosity is maintained is further extended.
It is possible to further increase the density and strength of the resulting cured product.

? The modified fat is cationic and improves the dispersion of the material, so it is thought that it disperses fine amorphous silica well in the cement, thereby further delaying gluing. In addition, this resin hardly inhibits the reaction of the cement, which has a water-reducing effect, and solidifies by drying, so it is thought that high density and high strength can be achieved. The amount added is 0.5% by weight, preferably 1 or more (if it is less than 0.5%, the effect is small) (Example) Next, an example will be described.

Example (people) Compared to 100 parts by weight of a mixture of T-type Portland cement 80% and No. 8 silica sand 20chi, 22927 people - 420H
8 (degree of Kelization 80%, degree of polymerization 2000) was added and mixed at a warm water ratio W/5 = 020-0.30, various amorphous materials were added to this, and extrusion was impossible due to the addition of water. I asked for the time it would take. (It was considered that it could not be extruded when it was mixed in a mixer and the waxy consistency disappeared and the mixture became ・9 soybeans.) Comparative Example 2 Ordinary I Rutland Cement 5 ott * No. 8 silica sand
3 parts by weight of Krat/PVA-420H8 was added to 100 parts by weight of 20% by weight, and the extruder (
Honda Iron Works), but gluing occurred and molding was impossible. In the case of press molding of 200 kliJ/m'' with the same composition, ρ=2.05 and the bending strength was 150 kg~.

Example 6 The formulation of Example 3 in Table 1 was molded using an extruder and heated to 60°C.
After curing for 5 days at (4)°C, it was dried for 24 hours.

the result Bulk density 2.1 Bending strength is 280 kg□.

Example 7 Molded with an extruder having the formulation of Example 4 in Table 1, 6o'a
After curing for 5 days at (a), it was dried at ℃ for 24 hours.

the result The bulk density was 215, and the bending strength was 33o Toya.

Example (B) Ordinary I citland cement 80 weight It% No. 8 silica sand
For 100 parts by weight of 20% by weight, Kraty PVA-420H8
Add 3 parts by weight and mix water ratio W/S = 015-0.2
5, various amorphous silicas were added thereto, MK-300H (I-Ryamido-Epichlorohydrin-modified resin manufactured by Kindai Kagaku Co., Ltd.) was added, water was added, and Oshimata paste was mixed with 40% of Ordinary I Lutra/Docement. jl chislag
40% by weight No. 8 silica sand, 20 weights, 1IL-CH Each system was extrusion molded, cured at 60°C for 5 days, and (a) dried at °C for 24 hours to determine bulk density and bending strength.

Table 4 (Effects of the Invention) As shown on the board, the present invention enables extrusion molding of cement containing Portland cement by adding vinyl acetate polymer, and scales a highly dense and high-strength cement-based hardened product. I can do that.

Furthermore, by adding polyamide-epoxy modified m fingers, even higher density and higher strength can be achieved.

Claims (2)

[Claims] (1) When extrusion molding a cementitious hardened body containing Portland cement as a hydraulic substance, a method for producing a cementitious hardened body, which is characterized by using a vinyl acetate resin as a binder and further adding amorphous silica. (2) When extrusion molding a cement-based cured product containing Portland cement as a hydraulic substance, it is recommended to use a vinyl acetate resin as a binder, further add amorphous silica, and further add a polyamide-epoxy modified resin. A method for producing a cement-based hardened body according to claim 1.