JPS63206346A - Injection material for repairing concrete structure - 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] Industrial Application Field The present invention relates to an injection material for repairing concrete structures by injecting them into floating mortar parts and fine cracks in concrete structures to maintain their functionality. It is.

The purpose of the gypsum in the injection material of the present invention is to control the solubility at the initial stage of water use, increase strength over a long period of time, and reduce shrinkage, and gypsum other than β-hemihydrate gypsum can be used. In principle, high-performance water reducing agents are premixed, but they can be added at the time of on-site use. In addition, a shrinkage reducing agent (trade name: Tetra Guard, manufactured by Sanyo Chemical Co., Ltd.) was added to the injection material at 1 to 3%.
Furthermore, polymers can be used in combination with K depending on the purpose.

Recently, the number of structures that require repair has been increasing due to aging and early deterioration of concrete structures. In particular, there is a need to repair cracks and floating concrete structures, and the injection method is used as the optimal repair method. The general injection method is pressurized injection using a pump, but when injecting into concrete structures, the pressure is low (2 to 3 forces or less) due to the strength of the structure.
This requires a material with good injectability.

Epoxy resin is used as a conventional injection material, but
Epoxy resins are expensive and even less economical when injected in large quantities. In addition, the presence of water gaps inside cracks in concrete poses problems in long-term durability, and inorganic materials are being reconsidered. However, conventional cement-based materials contain coarse particles of 1004 m in diameter, and Portland cement-based materials have injectable properties such as K111 due to particle agglomeration due to initial rapid hydration and an increase in apparent particle size due to physical aggregation.
Although it has been applied to cracks of Ill 2 m or more, it has been pointed out that there are drawbacks such as volume change KI [1 problem] when the crack width is large. In particular, microcracks (0,
3) Cement-based injection materials that can be applied to K have not been put to practical use.

Concrete crack investigation, repair, and reinforcement guidelines (draft) K
According to the above, the crack width limit regarding whether or not repair is required is ``0.2 m or less and 1 m or less in terms of waterproofness'' if repair is required.
In terms of durability, it depends on various conditions, but it is 0.4 to 1. O
vm or more.

Problems to be Solved by the Invention The present inventors conducted research to overcome the various drawbacks of conventional cement-based injection materials and obtained the following knowledge.

For injection materials to be injected into micro-cracks in concrete structures, it is preferable that the particle size of the injection material is as small as possible and that it has low viscosity even when the water-to-injection material ratio is lowered, so that it hardens uniformly without material separation after injection. In the body, the entire injection material slurry solidifies,
In the long term, it will be necessary to integrate it with the concrete structure. Reducing the particle size of Portland cement increases its reactivity, and when it comes into contact with water, rapid reactions occur, namely chemical aggregation due to the initial hydration reaction and physical aggregation due to low water ratios, making it impossible to achieve the purpose of pouring. There are additives such as retardants that prevent water use, but they mainly suppress the water use of calcium aluminate, which contributes to the initial hydration contained in Portland cement, and do not suppress other residues such as calcium silicate. Although there is a slight improvement effect, it cannot be put to practical use.

Means for Solving the Problem It is already widely known that pulverized blast furnace slag powder hardens due to the stimulating action of OH-ions and sulfates liberated by the hydration of Portland cement. In other words, even when blast furnace slag is highly pulverized, it does not react particularly rapidly when it comes into contact with water, and the reaction that occurs after the initial hydration of Portland cement and the dissolution of sulfate is due to its fineness! ! It has nothing to do with. This makes it possible to suppress hydration for a certain period of time even if it is made into a highly fine powder like slag in order to improve pourability, prevent viscosity changes, secure pot life, and prevent micro-cracks in concrete. It was found that it is possible to pour, has low material separation, and has good curing characteristics after pouring.

Function In the present invention, the fineness of the injection material is adjusted to the Blaine ratio surface 4a.
Rather, it was specified by the maximum particle size and the residual amount below 2 JIm, because the Blaine specific surface area changes greatly depending on the residual amount below 2 μm, and the Blaine specific surface area also changes depending on the form and amount of gypsum contained. Therefore, it is reasonable to specify a single grain size. Particle size is measured using a laser microsizer (manufactured by Seishin Enterprises) using a dispersion medium pressure in distilled water, and the particle size is controlled using standard samples commercially available from the Cement Association. From various experimental examples, it has been found that the product of the present invention has a maximum particle diameter of 16 μm or less, a mass residue of 2 μm or less is 30 μm or less, the blast furnace slag has a weight of 45 to 97 μm, and the gypsum has a minimum particle size of 3 fi required for coagulation. Considering shrinkage improvement after curing from quantity duck! Up to 5 weight ducks.

Examples will be explained below in order.

Using the samples shown in Table 1, slurries with various water injection ratios were prepared and tested for injection properties and material separation (breathing). Regarding injection into cracks, there is no established test method such as JI8, so assuming actual injection using injection plugs and rods, steel JL150X20
0cm cylindrical tube (inner volume 400cO) (7) Width 0cm at the bottom.
3cm, 0.5cm, length 38m (a DX lit was installed, and after stirring the injection slurry of each water injection ratio with a mixer for 3 minutes, the slit was closed, and the cylindrical tube was filled with 400 CC of slurry, The slit was opened, and the amount of slurry flowing down at each elapsed time was measured using a cylinder to compare the injection properties.The viscosity was funnel viscosity, and the JA funnel (inner volume 1000 CO)
It depended on the flow time. Material separation is based on the Japan Society of Civil Engineers standard Bure・f
The breathing rate and expansion rate of concrete poured mortar were measured by the test method.

Table 2 Comparison table of pourability and material separation The pourability, viscosity, and material separation are as shown in Table 2. Ordinary Portland cement causes instantaneous Kcn clogging after the slit is opened, and only filtered water droplets fall. It was confirmed that this phenomenon remained the same even when pressure was applied, making injection impossible. In addition, although Comparative Amount 4, which has been made into a highly fine powder, has improved pourability compared to ordinary Portland cement, it gradually generates KvI4M and increases in viscosity over time, and has better pourability than the product of the present invention. is inferior. Although the product of the present invention is inferior to K in pourability by reducing the blended amount of fine slag powder, it can be put to practical use, and has reached the scope of the claims of the present invention. Furthermore, it was confirmed that using the product of the present invention, the pot life could be maintained for 90 minutes when the flow loss was 2 seconds due to viscosity change.

Next, the strength of the product of the present invention was determined according to JIS R5201,
Bending and compressive strength tests were conducted on a 4X4X16clR specimen.

Table 3 Strength Test Comparison Table From Table 3, it was found that the products of the present invention exhibited higher strength than the comparative products, even though the water ratio was large.

In the product of the present invention, when the blending amount of fine slag powder is increased, the initial strength is low, but sufficient high strength is developed in the long term. In the product of the present invention, the formation of calcium sulfoaluminate and calcium silicate hydrate was observed at the initial stage of the material, and from the 7th day of the material age, due to the pozzolanic reaction, dense calcium silicate hydrate was formed over the long term and hardened. As the body becomes more dense, strength develops and water permeability improves 4! It is expected that this will contribute to the

Next, the adhesive strength and water permeability coefficient were tested. Adhesive strength was determined using JISR5201K, a mortar with a water ratio of 50% and a cement-sand ratio of 1:2 was prepared, and after curing in water for several days,
Cut it in half with a cutter, sand the adhesive surface, sandwich the spacer so that the adhesive thickness is 1.0μ, inject the injection material slurry while applying slight vibration, and after curing in a humid air for 1 day, It was cured to maturity and measured according to JIS A 6024K. The hydraulic conductivity is f! Regarding the J5×10c1m specimen, the constant water level (2*/J) was measured using a three-wheeled compression tester.
It was done by law.

As shown in Table 4, the results showed that the adhesive strength exceeded that of the comparative product, and on the 28th, it was 50 Ky for products 1 and 2 of the present invention.
− can be secured. In the long term, it can be judged that the adhesive strength of 10 will increase due to the reaction with the alkali eluted from the mortar.

Ru.

Table 4 Comparison Table of Adhesive Strength and Hydraulic Permeability Coefficient A value on the order of 10711 (~做) can be obtained for the hydraulic permeability coefficient due to the characteristic water use reaction of the present invention.

The chemical resistance and salt tolerance of the product of the present invention were tested on chickens. JI8R52
A fi4X4X16cl11 (7) specimen was prepared according to 01, and the chemical resistance was determined by exposing it to a 5% sulfuric acid solution Vc at 14 days of age, and measuring the weight change for each dilution period.
Smeared in Cl solution, 28 and 56 days later K O, l N
Apply AgNOs solution and AgC1! The white part generated by CI! - measured as the penetration depth. The result is the fifth
This is the table below.

Table 5 Chemical resistance and salt resistance comparison table Effect of the invention As shown in the results of Tables 2 to 4 and the results of Table 5,
The product of the present invention has excellent resistance to sulfuric acid solutions and salts. This is due to the physical and chemical properties of the hydrate of the product of the present invention. Concrete structures often suffer from erosion and cracking due to hot spring water and mine water containing sulfate radicals, sea salt particles containing C, etc.

From this, it can be said that the product of the present invention is extremely useful for repairs in such cases.

One of the characteristics required for repair injection materials is volume change, that is, drying shrinkage, but this is improved by using non-shrinkage materials, and it is 0.1 to 0.2 at 20° CRH 60% and material age 28 days.
It falls within the range of ducks. This value is large when judged from the value of commonly used concrete and the standard value (0.05%) of poured mortar for prepact concrete according to the Japan Society of Civil Engineers, but the crack width of concrete to which the present invention is applied is small. Also, since it is often sealed after repair, the effect of drying is actually extremely small, and since it is injected under a constant pressure, it is subjected to compressive stress after injection, so even if shrinkage occurs, the stress is alleviated. There are advantages. however,
It must be said that even the product of the present invention has its limits in terms of crack repair pressure during the growth process.

As a result of various research, we were able to invent an unprecedented cement-based injection material with high pourability, which can be applied to all kinds of concrete structures through various construction methods, and is expected to play a major role in concrete repair, including its economic efficiency. is expected.

Claims (2)

[Claims] (1) An injection material consisting of blast furnace slag, gypsum, and portland cement clinker, with a maximum particle size of 1
An injection material for repairing concrete structures characterized by high pourability, seawater resistance, and chemical resistance, consisting of 30% or less of mass residue of 6 μm or less and 2 μm or less. (2) Contains 0 to 3.0% of a high performance water reducer in terms of solids for the injection material which is in the range of 45 to 97% by weight of blast furnace slag, 3 to 15% by weight of gypsum, and 0 to 40% by weight of Portland cement; A composition according to claim 1.