阅读说明：本技术 砂浆及其制备方法 (Mortar and preparation method thereof ) 是由 松田拓 峯竜一郎 于 2018-12-26 设计创作，主要内容包括：提供了自收缩应变小的砂浆及其制备方法。砂浆包含细骨料和含有水泥与矿物质细粉的粘合剂,并用水混合而成。细骨料为风碎的镍铁渣,水相对于粘合剂与细骨料的总质量的质量比为7.0％以上,9.0％以下。这种砂浆通过混合含有水泥与矿物质细粉的粘合剂、细骨料和水来制备。(Provided are mortar with small self-contraction strain and a preparation method thereof. The mortar comprises fine aggregate and a binder containing cement and mineral fine powder, and is mixed with water. The fine aggregate is air-broken ferronickel slag, and the mass ratio of water to the total mass of the binder and the fine aggregate is more than 7.0% and less than 9.0%. This mortar is prepared by mixing a binder containing cement and mineral fines, fine aggregate and water.)

1. A mortar comprising a fine aggregate and a binder containing cement and a mineral fine powder, and being mixed with water, wherein the fine aggregate is air-pulverized ferronickel slag, and the mass ratio of water to the total mass of the binder and the fine aggregate is 7.0% or more and 9.0% or less.

2. The mortar according to claim 1, wherein the fine aggregate has a water absorption of 1.5% or more and 3.5% or less and an equilibrium moisture content of 0.10% or more and 0.30% or less.

3. A method for producing a mortar, which comprises mixing a binder comprising cement and a mineral fine powder, a fine aggregate and water, wherein the fine aggregate is air-pulverized ferronickel slag, and the mass ratio of water to the total mass of the binder and the fine aggregate is 7.0% or more and 9.0% or less.

Technical Field

The invention relates to mortar and a preparation method thereof.

The present application is based on the japanese patent application JP 2018-001922, filed on 10.1.2018, and claims priority based on this application. This application is incorporated by reference herein in its entirety.

Background

In the mortar, in order to suppress the generation of cracks, it is desirable to control the self-contraction strain to be small. Patent document 1 discloses that a mortar with a small self-contraction strain can be obtained by setting the porosity of the fine aggregate to 16% or more.

Patent document 1: JP 2016-

Disclosure of Invention

Although the mortar described in patent document 1 is excellent in suppressing the self-contraction strain, the self-contraction strain is further suppressed as required by the application.

The invention aims to provide mortar with small self-contraction strain and a preparation method thereof.

The mortar of the present invention comprises fine aggregate and a binder containing cement and mineral fine powder, and is formed by mixing water. The fine aggregate is air-pulverized ferronickel slag, and the mass ratio of water to the total mass of the binder and the fine aggregate is 7.0% or more and 9.0% or less.

The method of preparing the mortar of the present invention comprises mixing a binder comprising cement and mineral fines, fine aggregate and water. The fine aggregate is air-pulverized ferronickel slag, and the mass ratio of water to the total mass of the binder and the fine aggregate is 7.0% or more and 9.0% or less.

According to the present invention, mortar with small self-contraction strain and a method for producing the same can be provided.

The above and other objects, features and advantages of the present application will become apparent from the following detailed description, which proceeds with reference to the accompanying drawings, which illustrate the present application.

Drawings

Fig. 1A shows the change with time of the self-contraction strain in examples and comparative examples.

Fig. 1B shows changes over time in the self-contraction strain in examples and comparative examples.

Detailed Description

The invention is illustrated by the following examples. The mortar of the present invention comprises a binder and a fine aggregate, and is prepared by mixing with water. In addition, the mortar of the present invention is particularly suitable for grouting.

The binder comprises cement and mineral fines. The types of the cement are not limited, and various Portland cements such as common, medium-heat, low-heat, rapid hardening, ultra-rapid hardening, sulfate resistance and the like can be used; mixed cement such as blast furnace cement, fly ash cement, silica fume premixed cement and the like; ultra-fast hardening cements such as aluminum cement, spray cement, and the like; hydraulic cement (アーウィン series セメント) and the like. For Portland cement, the cement content is preferably from about 500 to 600kg/m³For blended cements, the cement content is preferably about 600 to 1000kg/m³。

As the mineral fine powder, blast furnace slag fine powder, fly ash, silica fume, or the like can be used. The fine blast furnace slag powder is a by-product produced in a process for producing pig iron from iron ore, and contains CaO and SiO₂、Al₂O₃MgO, and the like. The blast furnace slag fine powder is preferably blast furnace slag fine powder conforming to JISA6206 "blast furnace slag fine powder for concrete". Although the content of the blast furnace slag depends on the content of other fine mineral powder, it is preferably about 200 to 300kg/m³. Fly ash is an industrial waste produced in coal-fired power plants. Fly ash mainly contains SiO₂、Al₂O₃. The fly ash is preferably one that satisfies any one of I to IV specified in JIS A6201 "fly ash for concrete". The content of the fly ash is preferably 150-350 kg/m³Left and right. The silica fume is a by-product produced when silicon or ferrosilicon is produced in an electric arc furnace, and mainly contains SiO₂。

In order to exhibit the performance as a binder, a binder performance-imparting material may be added to these fine mineral powders. As the adhesion performance expressing material, an alkali stimulating material which becomes alkaline in an aqueous solution after being mixed with water is preferably used, and for example, an expanding material can be used. The swelling material refers to calcium ion (Ca (OH) when put into water₂) The eluted material is preferably an expansive material conforming to JISA6202 "an expansive material for concrete". CaO and SiO contained in the calcium ion and mineral fine powder₂Slowly react at normal temperature to generateA compound having binding ability. The content of the expanding material is preferably about 10 to 30kg/m³。

The kind of water is also not particularly limited. The water content is preferably about 150 to 200kg/m³。

The fine aggregate is air-broken ferronickel slag (FNS). Ferronickel slag is a by-product produced when nickel is extracted from nickel ore. When a raw material such as nickel ore is supplied to an electric furnace, the raw material is separated into ferronickel and slag in the electric furnace, and the slag is taken out from the electric furnace. The slag is then separated into fine spherical particles by high pressure air injection. This process is called wind shredding. The separated particles fly in the air, colliding with the wall. During this time, the high temperature particles slowly cool and eventually solidify into a spherical shape. The ferronickel slag produced in this way has a hard surface and a small thermal shrinkage rate, and therefore has the effect of suppressing the self-shrinkage strain of the mortar. Hereinafter, in the present specification, FNS produced by air classification may be referred to as air classification FNS.

The water absorption of the fine aggregate is preferably 1.5% or more and 3.5% or less. Here, the water absorption is defined as (water absorption/absolute dry mass) × 100 (%). The water absorption amount is the mass of water when the surface of the fine aggregate is dry (surface-dry state), the internal voids of the fine aggregate are saturated with water, and the absolute dry mass is the mass of the fine aggregate when the surface and internal voids of the fine aggregate are free from water. That is, the water absorption rate indicates the water absorption capacity of the internal voids of the fine aggregate. The equilibrium moisture content of the fine aggregate is preferably 0.10% or more and 0.30% or less. The equilibrium moisture content is the moisture content when the moisture content does not change (decrease) during drying of the fine aggregate. The equilibrium moisture content is determined as a saturation point of the moisture content when the fine aggregate is dried, for example, in an environment where the temperature is about 20 ℃ and the relative humidity is about 95% after the water-saturated state. As a result of experiments, it was found that a fine aggregate satisfying these conditions is less likely to shrink, and that the self-shrinkage strain of a mortar using the less likely to shrink fine aggregate can be suppressed. Examples of the fine aggregate satisfying these conditions include Pamuko Sand (パムコサンド) (registered trademark) manufactured by Atlantic Metal Corp. The water absorption rate of Pamuko Sand is 1.8-3.2%, and the equilibrium water content is about 0.1-0.3%.

A high water absorption and a low equilibrium moisture content means that more water is released from the fine aggregate and correspondingly less water is added. In general, the amount of water to be added in the preparation of mortar is planned on the premise that the fine aggregate is in a water-saturated state, and therefore the fine aggregate having a high water absorption rate and a low equilibrium moisture content plays a more important role as a water supply source than the ordinary fine aggregate. The detailed mechanism is not clear, but it is presumed that water held in a large amount in the internal voids of the fine aggregate affects the reaction mechanism between cement and water, and contributes to suppression of the self-shrinkage strain of the mortar. In the mortar of the present invention, the mass ratio of water to the total mass of the binder and the fine aggregate (W/(B + S)) is preferably 7.0% or more and 9.0% or less, and more preferably 7.5% or more and 8.8% or less. In the standard formulation of a general commercial shrinkage-free grouting (comparative examples 6 to 8), the mass ratio of water to the material is about 10 to 20%, and therefore the mass ratio of water to the total mass of the binder and the fine aggregate is less than this in the present embodiment. Therefore, W/(S + B) is 7% or more, and 9% or less means that the ratio of water is smaller than that of ordinary mortar, or that the ratio of the total mass of the binder and the fine aggregate is larger than that of ordinary mortar.