JP2000086318A - Highly expandable grouting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-strength hardened form with initial expansion ratio by including cement, an expanding agent, aggregate, and a water-reducing agent. SOLUTION: The initial expansion ratio of the subject grouting material is designed to be >=3%, and the compressive strength of the hardened form obtained from the grouting material to be >=25 N/mm2 on 28 day of material age. An expanding agent to be used is metallic powder, in particular aluminum powder surface-treated with stearic acid or the like, making use of foaming phenomenon owing to hydrogen gas generated by reaction of the metallic powder with an aqueous calcium hydroxide solution. The amount of the expanding agent to be used is set at 0.005-0.015 pt.wt. based on 100 pts.wt. of cement such as high-early-strength Portland cement, and combination of the expanding agent with a water-reducing agent enables the aimed high-strength grouting material of high expansion ratio to be prepared. Aggregate to be used is e.g. river sand, mountain sand, lime sand, the cement/aggregate ratio and water/ cement ratio are set at 0.5-1.5 and 0.3-0.6, respectively. The water-reducing agent to be used is e.g. a salt of β-naphthalenesulfonic acid-formaldehyde condensate or the like which is used at 0.1-1 pt.wt. based on 100 pts.wt. of the cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a highly expandable grout material used in the fields of civil engineering and construction.

[0002]

2. Description of the Related Art There has been known a grout material in which a water reducing agent, a swelling agent, and fine aggregate such as river sand and silica sand are mixed with cement. Applications for grout materials include PC grout, grout for prepacked concrete, grout for backfilling tunnels and shields, grout for precast, repair of structures, grout for reinforcement, grout for rebar joints, grout under bridge supports, machinery Grouts under pedestals, grouts under paving slabs, grouts under track slabs, grouts under reactor containment vessels, and the like. Various methods have been devised for these grout materials to exhibit appropriate expandability as a non-shrink material, and the expansion rate of a general grout material is 1.0% or less (Patent Publication 27120).
No. 07). Then, if an attempt is made to obtain an expansion coefficient higher than this, there is a problem that the strength is remarkably reduced, and practical use is difficult.

As a result of various studies, the present inventors have found that the use of a specific grout material solves the above-mentioned problems, and has completed the present invention. The present invention is to develop a grout material having high expandability and high strength.

[0004]

That is, according to the present invention, the initial expansion coefficient is 3% or more, and the compression strength of the cured product at the age of 28 days is 25%.
A highly expandable grout material having a N / mm ² or more, which is a highly expandable grout material containing a cement, a swelling agent, an aggregate, and a water reducing agent.

Hereinafter, the present invention will be described in detail.

[0006] The initial expansion coefficient according to the present invention is 3% after kneading.
It refers to a value measured by the age of time, and is greatly affected by the temperature and the amount of the expanding agent added. In the present invention, it is important that the initial expansion coefficient of the grout material is 3% or more.
If the initial expansion rate is less than 3%, the filling properties may be poor.

A swelling agent is used for the expression of initial swelling,
As the expanding agent, metal powder, particularly aluminum powder (hereinafter referred to as Al powder) is used. Initial expansion rate of 3
% Or more, the compressive strength at the age of 28 days of the cured product to a 25 N / mm ² or more, it is important timing of foaming of the setting time and the metal powder of cement, it initial expansion and compressive strength greater Is preferred. The Al powder reacts with an aqueous solution containing alkaline calcium hydroxide to generate hydrogen gas and foams, and expands using the foaming phenomenon. The reactivity of the Al powder is important for controlling the expansion coefficient, and for example, a material obtained by treating the surface of aluminum particles, such as a material coated with stearic acid, is preferable. The amount of expanding agent used is based on 100 parts by weight of cement.
0.005 to 0.015 parts by weight is preferred. If the amount is less than 0.005 parts by weight, the expansion rate may be too small, and if it exceeds 0.015 parts by weight, the expansion rate may be large and the strength may be greatly reduced.

As the cement used in the present invention, various types of Portland cement, such as ordinary and early strength, various mixed cements obtained by mixing blast furnace slag or fly ash with Portland cement, and low heat-generating cements are used. Among them, early strength Portland cement is preferred, and Al powder surface-coated with stearic acid,
By combining with a water reducing agent, it is possible to prepare a grout material having a large expansion coefficient and good strength.

As the aggregate used in the present invention, generally used river sand, mountain sand, lime sand, and the like can be used.
The cement / aggregate ratio is preferably in the range of 0.5 to 1.5,
-1.2 is more preferable. If it is less than 0.5, the generation of bubbles may be excessive, and if it exceeds 1.5, the generation of bubbles may be reduced. The grain size of the sand is about 3.5 or less in terms of coarse grain ratio (FM).

In the present invention, the selection of the water / cement ratio is important, preferably from 0.3 to 0.6, more preferably from 0.4 to 0.5. If it is less than 0.3, the expansion coefficient decreases, and if it exceeds 0.6, the strength may be low.

The water reducing agent used in the present invention improves fluidity and reduces the water-cement ratio. Specifically, salts of β-naphthalenesulfonic acid formaldehyde condensate and salts of melamine sulfonic acid formaldehyde condensate are used. , Ligninsulfonic acid salts, and polycarboxylic acids or salts thereof. Further, it can be used in combination with saccharides such as oxycarboxylic acid or a salt thereof, dextrin, and sucrose. In the present invention, it is preferable to use a combination of two or more of these water reducing agents. The amount of water reducing agent used is cement
0.1 to 1 part by weight per 100 parts by weight is preferred. 0.1
If the amount is less than 1 part by weight, fluidity may not be obtained. If the amount exceeds 1 part by weight, bleeding may occur.

[0012] There are various as a method of evaluating the fluidity, the present invention was evaluated with P ₁₃ funnel method, the falling value of 20
Seconds or less are preferable, and 16 seconds or less are more preferable. If it exceeds 20 seconds, the fluidity is low and the filling property may be insufficient. On the other hand, if the falling value is too low, bleeding may occur and the quality of the grout material may deteriorate. The bleeding rate is preferably 2% or less.

The grouting and kneading machine of the present invention includes:
A hand mixer, a forced stirring mixer, a continuous kneading mixer, a tilting mixer, or the like can be used, and those having strong stirring power are preferable. The method of kneading is not particularly limited, but usually, after the kneading container is filled with predetermined water, cement and aggregate are added and kneaded. In a raw conplant, a method is used in which, after mixing aggregate and cement, water is added and kneaded.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples.

Experimental Example 1 Water was added to a stainless steel container so as to have a water / cement ratio of 0.48, and then 0.6 parts by weight based on 100 parts by weight of cement, the expanding agent shown in Table 1, and 100 parts by weight of cement. After adding the water reducing agent, the aggregate was put so as to have a cement / aggregate ratio of 1, and kneaded with a hand mixer for one and a half minutes to prepare a mortar. P ₁₃ funnel flow time of the prepared mortar, initial setting time, bleeding rate, and initial expansion, as well as to measure the compressive strength of the cured product. The results are also shown in Table 1. The curing of the specimen is 1 at 20 ° C and 80% RH.
After a day, curing in water at 20 ° C. was performed.

<Materials Used> Cement A: Portland cement with early strength, commercial product Cement B: ordinary Portland cement, commercial product Expanding agent: Al powder with surface coating, commercial product Aggregate: lime sand aggregate, coarse grain ratio (FM ) 2.5 Water reducer: Main component, naphthalene, commercial product

[0017] <Measurement Method> P ₁₃ funnel flow time: the Japanese Society of Civil Engineering standard, JSCE-F521 compliant initial setting time: JIS R 5201 "of cement physical test methods /
Bleeding rate: Compliant with JSCE-F522, expansion rate: Compliant with JSCE-F522, Compressive strength: Compliant with JSCE-G521

[0018]

[Table 1]

[0019]

According to the present invention, there can be obtained a grout material having a higher expansion coefficient than the conventional grout material and having good strength.

Claims (2)

[Claims] 1. A highly expandable grout material characterized by having an initial expansion rate of 3% or more and a compressive strength of a cured body of 28 days or more of 25 N / mm ² or more. 2. The highly expandable grout material according to claim 1, further comprising a cement, an expanding agent, an aggregate, and a water reducing agent.