JPS5912615B2 - Super fast hardening cement - Google Patents

Description

[Detailed description of the invention] The present invention relates to super-heavy hard cement.

Cement is used to manufacture secondary concrete products by mixing this with various materials such as sand and ballast, and pouring the resulting ready-mixed concrete into a predetermined mold and curing it.

In this case, a curing period of about one week or more is usually required, so in the case of construction work, the construction period becomes correspondingly longer, and in the case of secondary concrete products, a large area of land is required to store the semi-finished products.

For this reason, steam curing has been adopted to shorten the curing period, but this is not preferred because it requires a large amount of heat and a lot of labor.

The clinker of recently developed ultra-heavy hard cement is Al2.
Approximately 1 to 3 moles of CaSO4 per mole of O3.nSiO2
and about (0,5~2) + 2 moles of CaCO3 (however, n is 1.5~2.5),
O*S A02 + A1203 and SO3 raw materials are mixed and fired at a high temperature of about 1200°C to 1600°C for about 1 to 5 hours, and the composition is β-2C.
aO-8t 02 (hereinafter referred to as β-C2S).

)3Ca0・3A1203・Ca504 (hereinafter 03A3
Indicated by 0.

), Ca 804 (hereinafter referred to as C8).

) In addition to 4Ca()A1203/Fe203 (hereinafter C
Indicated by 4AF.

) and Cab (hereinafter referred to as C).

), and the cement obtained by crushing the clinker becomes a hardened product with high strength in an extremely short period of time because C3A3C8 and C8 undergo a water utilization reaction abnormally quickly under low lime conditions.

For example, according to the cement mortar strength test specified in JISR5201, a compressive strength of approximately 150 kg/d is obtained after 3 hours of age, so this cement can be used in a wide range of practical applications, including secondary cement products. .

However, no matter how strict the process control is when firing the clinker, it is impossible to avoid slight variations in the quality and properties of this cement. However, since this cement is extremely hard and has a short setting time, it is extremely difficult to increase the construction speed in response to even a slight change in time.As a result, concrete mixers Construction problems such as breakdowns are likely to occur.

Even under normal circumstances, this cement sets and hardens too quickly.
When this is applied to concrete, it is difficult to adapt the setting to the setting and hardening speed, so a large amount of setting retarder must be used to achieve the optimum setting speed.

However, if a large amount of setting retarder is used, the resulting hardened product will not be able to take full advantage of the characteristics of a fast-setting cement, and its compressive strength and other properties will be significantly reduced.

An object of the present invention is to provide a super-heavy-hard cement that does not impair early strength development, has sufficient construction time required for kneading and molding into mortar or concrete, and has excellent workability.

Another object of the present invention is to maintain sufficient working time until curing without using a setting retarder, to increase strength quickly after setting, to be able to be demolded in an extremely short time, and to have sufficient early strength. The purpose is to provide a super heavy hard cement that can be obtained by curing the body in a short period of time.

The present invention provides super-heavy hard cement (hereinafter referred to as "super-heavy hard cement") containing at least 10 wt of C3A3 CS N, at least 8 wt% of chemically unbonded CK, and a small amount of free CaO, and whose main component is β-C2S. ) 755 parts by weight or above and 25 parts by weight or less of Portland cement are not only a mixture of the two, but also a mutual supplementation of the two, and produce a cement with special properties due to the synergistic effect of the two. It is based on knowledge.

The cement of the present invention is obtained by mixing one or more of the super-heavy hard cements and clinkers thereof with one or more of the portland cements and clinkers thereof.

More specifically, both clinkers may be mixed and ground simultaneously, or the former clinker may be mixed with separately ground Portland cement clinker, or the clinker may be mixed with Portland cement clinker and Portland cement. obtained by things such as

It is preferable that the amount of Portland cement added is 25wt or less in internal cutting considering the compressive strength of the resulting mortar, but it is preferably 40wt or less when considering construction points such as standard softness water amount and setting start time. Up to W t % of Portland cement can be added.

When the cement of the present invention is applied as mortar or concrete, it is extremely easy to work with and has an appropriate setting speed, allowing for sufficient construction time and ensuring safety without problems such as hardening of ready-mixed concrete in the mixer. Can be constructed.

Furthermore, if the cement of the present invention is applied as mortar or concrete, it will have a compressive strength greater than that of the hardened product obtained by applying the ultra-heavy hard cement alone used to prepare this cement. A cured product is obtained.

The cement of the present invention cures in an appropriate amount of time even without the use of a setting retarder, so it can be applied with sufficient time, and the strength of the cured product increases rapidly after application, allowing it to be demolded in an extremely short time.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto.

In the text, parts and subsections indicate parts by weight, respectively.

Example limestone powder (■g, 1oss43.1%, S A021
．． 0%, Ca055.1%, Mg00.5%) 45
part, removed gypsum (Ca032.2%, 5O345,7 parts%, Si 020.8%, Mg 00.1%, Fe
2030.1%, Ig 5los s 21.0%)
Part 27, Bauxite (AA20357.1 section, S +
025.9, Fe2O32.4%, M g 00.
7 L: f70, Ca00.1%, Igs 1oss
31.0%) 12 parts and Kanto Rohm (SiO□51,
5%, Al2O327.3, Fe2O37.5%, C
a00.6%, Mg00.5%, Igs1o
ss 11. Q%) 16 parts, and the mixed composition was fired at 1200°C for 1 hour in a pilot rotary kiln with an inner diameter of 50 cI'IL and a length of 7.5 m, and the chemical composition was I g, 1 oss 0.3%, 5i0214.2%,
A120316.0%, Fe2032.3, Ca04
A fired body having a ratio of 8.4, Mg 00.4%, and 5O317,3 was obtained.

The mineral composition ratio of this fired body is C3A3C829, C8
Section 13, β-C2S43, C4AF7, free Ca0
It was 0.4%.

This fired body was crushed with a pot mill to give a Blaine value of 4.4.
00cyyf/f! We obtained cement that is.

This cement and ordinary Portland cement were mixed in the proportions shown in Figure 1, mortar was prepared with the resulting mixed cement, and the compressive strength of the hardened product after curing for 4 hours was
The setting time (starting time) and standard softness water amount of each mortar were determined by the method specified in JISR-5201, and the results are shown in FIG.

As is clear from Figure 1, the amount of Portland cement mixed in (wt%) vs. compressive strength curve for ultra-heavy hard cement shows that the amount of normal Portland cement mixed in is 10 to 20 wt%.
Similarly, in the curve of normal portland cement content (wt%) - standard softness water content (wt%) for super heavy hard cement, a minimum value is observed when the normal portland cement content is 10 to 20 wt%. According to the mortar setting time vs. amount of normal Portland cement mixed in (wt fb ) for extra-heavy hard cement, the amount of mixed normal Portland cement is 10 to 20 W t.
From the fact that there was an abnormal deviation in the percentage, it was recognized that the cement made of super-heavy hard cement and ordinary Portland cement was not simply a mixture of the two, but a special type of cement was formed.

[Brief explanation of drawings]

The drawing shows the mortar of mixed cement consisting of ordinary Portland cement and super heavy hard cement after curing for 4 hours.
A curve between the compressive strength of the obtained hardened body and the amount of ordinary Portland cement mixed in, the standard softness water amount of the mortar, the setting start time of the mortar, and the relationship between the amount of ordinary Portland cement mixed in are shown.

Claims (1)

[Claims] 1 At least 10wt C3A3C transfer, at least 8w
z% chemically unbound Cg and a small amount of free CaO
clinker containing β-C2S as a main component and one or more of its cements with a weight ratio of 75 or more, and Portland cement clinker and one or more of its cements with a weight ratio of 25 or less. Super heavy hard cement made by adjusting the particle size.