JPS60235754A - Freeze-thaw resistant concrete - 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 [Field of Industrial Application] The present invention relates to concrete that has excellent freeze-thaw resistance. The present invention uses aggregate with a high water absorption rate of 3% or more (an object of the present invention is to provide concrete with excellent freeze-thaw resistance).

[Prior art] and [Problems to be solved by the invention] The freeze-thaw resistance of concrete using low-quality aggregate, that is, aggregate with a high water absorption rate, is quite low (this is a big problem in cold regions). In other words, in cold regions, the water in concrete freezes and melts during the day due to sunlight or heating.
It also freezes at night. Concrete deteriorates due to this phenomenon.The reason for this is that when water freezes, its volume increases, and the resulting water pressure destroys the internal structure of cement paste and aggregate. Particularly when low-quality aggregates with high water absorption or lightweight bone phase are used, the amount of water in the concrete becomes large (which makes it extremely difficult to prevent freezing, which poses a major problem).

Methods to solve this problem include spraying a box-shaped adhesive or coating material on the aggregate with high water absorption, treating the entire surface of the aggregate with water-soluble petroleum resin, and treating the entire surface of the aggregate with asphalt liquid. Methods have been reported that attempt to prevent frost damage rather than preventing water absorption, such as water-resistant treatment. However, these methods have not been put to practical use because surface treatment is troublesome and the adhesion strength between the surface-treated aggregate and cement paste is reduced.

Points [Means for solving the problems] The present invention has been made in order to improve the above-mentioned problems. By using and changing K, concrete with excellent freeze-thaw resistance was obtained.

The present inventors attempted to completely improve the freeze-thaw resistance of concrete by reducing the freezing pressure of water in the aggregate, and as a result of research, the present inventors discovered that the presence of a water structure-destroying agent in the freezing water was effective in reducing the freezing pressure of water in the aggregate. We have fully discovered that the object can be achieved and have completed the present invention.

That is, in the present invention, a water structure destroying agent is added to aggregate with a water absorption rate of 5% or more. The present invention provides concrete characterized by using impregnated aggregate.

[Effect]

The aggregate used in the present invention is a so-called low-quality aggregate or lightweight bone phase having a water absorption rate of 5% or more. In general, concrete using bone nt with such a high water absorption rate has poor freeze-thaw resistance and durability. "JISA5005 Quality Standards for Crushed Stone for Concrete" stipulates that the water absorption rate of bone phase is 5% or less.

However, in the present invention, a bone phase with a high water absorption rate, which is considered to be unsuitable as an aggregate for concrete, is used, and by completely impregnating the trapped water with a structural destructive agent, the pressure caused by freezing of water is reduced and the concrete is It is a freeze-thaw resistant gold-plated material.

A structure-destroying agent for water is a substance η that acts on water and has the effect of destroying the structure of the water molecules.

The water structure disrupting agents used in the present invention include urea, methylurea, ethylurea, and formamide.

(Tetamide, dimethylformamide, guanidine, etc. are suitable.

The following is the simplest method of impregnating the structure-destroying agent of water during fire pressurization into aggregate according to the present invention. i.e. 0.1 weight of the water structure disrupting agent) (more than -cent, preferably 1
．． Prepare an aqueous solution containing more than 0 cents (0 weight), and immerse the bone in this aqueous solution, or sprinkle this aqueous solution on the aggregate. If the bone phase is dried beforehand, the structure disrupting agent of water can easily penetrate into the aggregate.

The amount of water impregnated with the structure-destructing agent in the aggregate is 0.01 weight percent or more, preferably 0.1 N weight percent or more.

In the concrete according to the present invention, the paulownia material other than the aggregate used is a conventionally commonly used concrete filler. In other words, cements include ordinary Portland cement, early-strength Portland cement, blast furnace cement, fly ash cement, etc., admixtures include air-entraining agents, water-reducing agents, superplasticizers, early-strengthening agents, retarders, etc.; These include fine crystalline silica powder, fly ash 1, blast furnace slag, and an expanding agent.

Also, the method of manufacturing concrete is no different from the conventional method of manufacturing concrete.
It can be carried out in the same manner as the known manufacturing methods of fresh concrete, fluidized concrete, centrifugally molded concrete, steam-cured concrete, autoclave-cured concrete, high-strength concrete, and the like.

〔Effect of the invention〕

According to the present invention, concrete with excellent freeze-thaw resistance can be easily obtained even when using bone marrow having a high water absorption rate as described above, so that its industrial usefulness is greatly increased.

〔Example〕

The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these Examples.

Example Concrete having the composition shown in Table 1 was manufactured using the following materials. Concrete was produced by forced stirring (using a semi-mixer, and one batch of 501 concrete was produced. After mixing the concrete, the slump and air content were measured to confirm that they were within the target range, and then the specimens were prepared for freeze-thaw tests. It was created.

The freeze-thaw test followed ASTM O666 method A. The primary deflection vibration frequency of the concrete was measured immediately before the start of freezing and thawing and after 500 cycles of freezing and thawing, and the freeze-thaw resistance of the concrete was measured by calculating the relative dynamic elastic modulus using the following formula.

2 P = -X 100 2 where ICP: Relative dynamic elastic modulus (%) after 500 freeze-thaw cycles n: 1 blowing deflection vibration frequency at 0 freeze-thaw cycles n,: 1st-order deflection vibration frequency measurement result at 0 freeze-thaw cycles are shown in Table-2.

From the measurement results shown in Table 2, the freezing PH1j+ of concrete using crushed stone and artificial lightweight bone Uk with a water absorption rate of 5.2%
i! F resistance was low, and the concrete collapsed after 500 cycles. On the other hand, the relative dynamic elastic modulus of the concrete using the coarse aggregate impregnated with the structural destructive agent of water according to the present invention was 80% or more, indicating extremely excellent freeze-thaw resistance.

Paulownia wood cement used: Ordinary Portland cement (specific gravity 5.17
) Fine aggregate: Crushed stone from Kinoyo (specific gravity 2.57) Coarse aggregate: crushed stone from Takarazuka (ratio i2.,17, water absorption rate 5.2%)
) Artificial lightweight aggregate (trade name Mesalite, specific gravity 1.35, 24-hour water absorption rate 1α5%) Air entraining agent: Binnlu (Isuto Kagaku IR) Water structure destructor - Urea (manufactured by Wako Tsumugi Pharmaceutical Co., Ltd.) Formamide (Wako (Manufactured by Tsumugi Yaku Kogyo) Water: Tap water concrete mixture table -1 (Target slump 12 ± 2.5 kyo, Mekura Air Award 4 ± 1%)
``Additional amendment (voluntary) June 1980, 1311 11 Kazuo Wakasugi, Commissioner of the Information Agency, 1, JIG property indication patent application No. 1988-88992 2, name of the invention Concrete with excellent freeze-thaw resistance 3, amendment. Relationship with 1. Patent applicant (091) Hanajyu Soap Co., Ltd. 4 Agent Column 6 for detailed explanation of the invention in the specification Contents of the amendment (1) Page 2 of the specification, line 7 “ ...Monodesaru-0"
``...is a thing.

Claims (1)

[Scope of Claims] 1. Concrete characterized by using bone with a water absorption rate of 5% or more as aggregate, and bone@sound in which T4 is fully impregnated with a water structure-destroying agent. 2. Structural destruction of water in the aggregate. Agent impregnation lid is 0.01L
Concrete 3 according to claim 1, in which the impregnated amount of water in the aggregate is 0.1 percent or more. Water structure destructors include urea, methylurea, ethyl urea,
The concrete according to claim 1, which is selected from the group consisting of formamide, acetamide, dimethylformamide, and guanidine. Concrete 6 according to claim 1. Concrete according to claim 1, wherein the aggregate with a water absorption rate of 5% or more is an artificial lightweight aggregate.