JPH11258148A - Method and apparatus for testing surface deterioration of cementitious cured object by acidic water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a deterioration test means imitating a natural state in consideration of the physical force due to the acidity properties possessed by acidic water in a cementitious cured object such as concrete or the like and the movement of water. SOLUTION: A constant quantity per a time of acidic water 4 is sprinkled over the surface of a cementitious cured object comprising concrete, mortar or paste and the surface of the product applied to the surface of the cured object through a spray nozzle 5 so as to imitate a mode such that rain pours on a wall surface or applied to the surface of the product allowed to approach a vertical posture, after concentrated thereto through a concentrating plate 7 so as to imitate such a mode that rain is conc. along the surface of a roof to flow along the wall surface. Further, a process concentrating this water sprinkling through the concentrating plate 7 so as to imitate such a mode that conc. rain is applied to a floor locally in a waterfall state to apply the same to the surface of the product allowed to approach a horizontal posture under the setting of a predetermined falling height is repeatedly applied at a definite drying time interval and, thereafter, a change in the surface color of the product and a change in the surface roughness thereof are measured to evaluate the resistance against acidic water of the surface of the cement cured object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete cement, a mortar, a paste using a cement as a hardener, and a cement-based hardened body surface for testing the resistance of the surface of a material coated on the basis thereof to acid water. The present invention relates to a method and an apparatus for testing deterioration with acidic water.

[0002]

2. Description of the Related Art Concrete increases its strength due to the hydration reaction of cement.
H) Maintain strong alkalinity by ₂ and prevent corrosion of reinforcing steel. Acid rain has a function of neutralizing the concrete and a function of decomposing the cement gel if the pH is low to deteriorate the concrete.

[0003] Recently, environmental pollution due to acid rain has been regarded as a problem, and concrete buildings have phenomena such as formation of concrete vines in underground passages and under eaves, and peeling of mortar. There are several reports on the effects of acid rain on concrete. For example, the dissolution of concrete cement gel occurs not only in acid rain but also in neutral water, but the problem is speed, and in the current atmospheric environment there are many factors that promote it. The effect depends on the acid concentration and rainfall in the rainwater.

[0004] In order to maintain the concrete structure, the rate of deterioration of the concrete quality by acid is examined, and as a study on the effect of applying a coating agent as an easy acid resistance improving method, there is a conventional dipping method. This is to measure the compressive strength, weight loss, Ca ion amount, etc. of concrete after immersing the test specimen in acidic water.Since acidic water is always in contact with concrete, the concentration of acidic water is The test conditions vary depending on the eluted alkali, and the test conditions are not constant. Further, since the movement of the solution is small, it is impossible to give a physical force accompanying the movement of water such as rain. Therefore, when performing the acid rain resistance test,
Rather than the immersion method in which the pH rise is remarkable due to the elution of the alkali component in the concrete, the rainfall method using artificial acid rain at a constant pH can be said to be an appropriate method for simulating the natural state.

From the viewpoint of providing means capable of simulating the natural state described above, the means disclosed in Japanese Patent Publication No. Hei 7-92431 is considered to be suitable. In other words, this proposal was originally intended to conduct an accelerated test of corrosion of metal materials, paints, plating, polymer materials and the like outdoors, and in particular, acid rain caused by buildings, bridges, concrete, etc. It is said that it can also be used for accelerated corrosion tests.
This is a device that can test the deterioration due to light irradiation. It adds the light deterioration condition due to sunlight (the condition of light irradiation using the light source for weather resistance test) to the corrosion due to acid rain, and the initial condition of the sample during irradiation drying. It has been strongly desired to develop a device in which the temperature rise tendency is close to that of outdoor exposure (nature), the wettability of the sample surface can be dried in a short time, and the light amount of the light source for irradiating and drying the sample is constant. In response to that.

[0006] First, an acid rain solution is sprayed on a sample, and a sample wetted with the solution is irradiated with light from a light source for a weather resistance test to promote light deterioration, and the radiant heat of the light source is reduced. A test device that performs rapid drying using a test chamber. The test chamber is divided into two parts, the upper part is a lamp chamber, the lower part is a test chamber, and an openable and closable partition plate is provided to partition both chambers. Is provided with a light source for weather resistance test, a reflector above the light source for weather resistance test, a reflector for reflecting the light downward, and a filter for selectively transmitting the light below the light source for weather resistance test, A heater is placed in the space between the plate and the light source for the weather resistance test so as not to block the light from the light source.In the test room, a sample table on which the sample is placed on the floor and an acid rain solution on the side wall are placed on the sample table. Arrange a spray nozzle to spray the sample, and apply the conditioned air above the test chamber. A temperature control device that regulates the temperature in the test chamber by circulating from the bottom and discharging from below is installed.The partition plate is closed while the acid rain solution is sprayed, and the heater is controlled in addition to the radiant heat of the light source for weather resistance test Spray, heater, partition plate and temperature control so that the air in the lamp room is maintained at a high temperature, and the partition plate is opened simultaneously with the stop of the spray, and the temperature-controlled air is introduced into the test room to start the temperature control of the test room. An acid rain corrosion cycle tester equipped with a control device for controlling the operation of the device is used as the means.

However, since the artificial acid rain solution does not adhere to the filter in the lamp chamber by providing the shutter, the decrease in the light amount of the xenon lamp is eliminated, and the sample can always be irradiated with a constant light amount. Reproducibility is improved. In addition, by using a light source for a weather resistance test such as a xenon arc lamp, not only the radiant heat can be used, but also corrosion due to artificial acid rain in consideration of light deterioration of the sample can be promoted. The heat from the lamp was stored in the lamp room and was actively used. That is, when the shutter is opened and the circulating blower is operated, the air that has been adjusted to a high temperature in the lamp chamber falls together with the conditioned air that is blown into the test chamber. In the initial stage of drying the sample surface, the sample surface is exposed to this high-temperature air that descends with the conditioned air, and at the same time receives the radiant heat of the light source. It is possible to dry the wetting by the artificial acid rain solution in a short time. Therefore, for example, in a coating film sample, the coating surface is stained due to a rapid change in the salt concentration and pH of the artificial acid rain solution, and the coating film peels and swells due to the difference between the thermal expansion of the coating surface and the thermal expansion of the substrate. Such a phenomenon can be promoted and reproduced, and corrosion due to acid rain in consideration of light deterioration of the sample can be further promoted.

[0008]

In the above conventional means,
The considerations in simulating natural conditions are considered exceptional, but only when dealing with metallic materials, paints, plating, and polymeric materials. Cement-based hardened materials such as concrete decompose and elute cement hydrates due to the acidic properties of acidic water and the physical force of water movement, and are more affected by acidic water than metal plates and painted plates. Cheap. That is, the acidic water has two features, that is, the property as water and the property as an acid, and the cement-based hardened body deteriorates due to the two features. By the physical force of a substance having solubility and physical properties, which are the chemical properties of water, components that are easily eluted out of the cement hydrate on the surface of the cement-based hardened body are washed away. Decomposes cement hydrate, which is an alkaline substance, due to its properties as an acid. In order to reproduce the effect of the acidic water on the cement-based cured product, it is necessary to add these two elements. For this reason, under the additional conditions described in Japanese Patent Publication No. Hei 7-92431, it is not possible to accurately understand the influence of the difference in the mix of concrete, the type of cement, etc. on the progress of surface deterioration.

[0009] Since the physical force of water cannot be sufficiently imparted only by spraying the acidic water, the effect of the acidic water on a material such as cement hydrate, which is liable to be dissolved or decomposed, is sufficiently examined. I can't say it's simulated. In fact, as a result of using the apparatus shown in Japanese Patent Publication No. Hei 7-92431 for concrete, (1) the depth of neutralization could not be confirmed in the accelerated deterioration test. This is because carbonation is mainly CO2
_This is a reaction between ₂ and Ca (OH) ₂ , and the influence was small because the specimen was placed in the test tank and the supply of CO ₂ gas was not performed. (2) There was no clear difference in the effect of the amount of eluted Ca on the compressive strength. Since the artificial acid rain spraying method is the same as rainfall in a natural state and hardly penetrates, 1-1.
This is because five years of rainfall did not progress until the internal cement gel decomposed. It has been pointed out.

[0010] In addition, the results of investigations on the effect of the pH of rainwater on the change in color tone of mortar have been reported, and the following has been clarified. (1) The hue and saturation of the mortar surface became reddish brown due to the acid rain. (2) The sample using the admixture became reddish brown due to acid rain. (3) It was understood that blast furnace slag under acid rain environment suppressed color (hue) change more than other admixtures. (4) Dirt due to acid rain tends to break the balance between lightness and saturation in color harmony. (5) It was found that the cement-based material mainly changed the iron color contained in cement from the action of acid and changed the body color to reddish.

From the above, the surface deterioration of the cement-based hardened material includes a change in color which is caused as a result of the deterioration of the cement hydrate. It is clear that the resistance to degradation cannot be evaluated accurately. The present invention has been made in view of the above circumstances, and its purpose is to accurately reproduce the effect of acidic water on a cement-based cured product,
Further, it is intended to provide a means for accurately evaluating the resistance to surface degradation due to acidic water by accurately grasping the influence factors.

[0012]

In order to achieve the above object, the present invention provides a method for testing the deterioration of a cement-based hardened material surface with acidic water, comprising the steps of: Simulates a mode in which rain falls on the wall surface of the product coated on the surface of the product, spraying a certain amount of acidic water per hour through a spray nozzle, and a mode in which rain concentrates on the roof and then flows on the wall surface Simulating the water spray through the concentration plate and then hitting the surface of the product approaching the vertical position, and further simulating the mode in which the concentrated rain hits the floor locally in a waterfall shape. A process of applying the product to the surface of the product which has been brought close to a horizontal position under a predetermined drop height setting after concentrating via the concentration plate is repeatedly added after a certain drying time, and then the product surface By measuring the change in and the surface roughness change in, in which the evaluating resistance to acid water cement surface.

[0013] The apparatus for testing the deterioration of a cement-based cured product surface with acidic water according to the present invention comprises:
Adjustable flow rate and water droplet diameter, while spraying, adjust the amount, flow rate and water droplet diameter so that acidic water is sprayed at a constant concentration and a fixed amount. The apparatus comprises the apparatus, the spray nozzle, and an acidic water concentration plate disposed at a predetermined height in front of the apparatus.

When the hardened cementitious body is affected by acidic water, the change in the state that appears on the surface as deterioration is caused by a change in the balance of the mineral composition on the surface accompanying the decomposition and elution of the cement hydrate. And the change in surface roughness caused by the decomposition and elution of cement hydrate. Therefore, it is necessary to measure these two changes in order to grasp the influence of the acidic water on the cement-based hardened material. According to the present invention, the change in color and surface roughness of a cured product is measured, the magnitude of the effect of acidic water is determined based on the degree of the change, and the resistance of the cured product to acidic water is evaluated. The surface color and the surface roughness can be easily measured with only an apparatus, and there is almost no variation among the operators. The color shall be measured after the surface of the cured product has been sufficiently dried so that the effect of the color change due to moisture does not occur.
It is desirable to use a color difference meter capable of displaying EXYZ, CIE L * a * b *. Surface roughness is JIS B
It is desirable to perform measurement with a device having a performance higher than that of a device conforming to 0651.

[0015]

According to the present invention, a physical force, which is one of the properties of acidic water, is applied to the cured product by a method of watering and centralizing watering. When acidic water actually affects the hardened cement body, when it hardly hits the hardened body such as the outer wall of the building as acid rain as small acidic water droplets on average, or when the acid rain collects on the roof and the large amount of water collects on the concrete floor, etc. And so on. In the conventional method, the physical power of water is not given, or it is only given as an average of the power of rain, so it does not sufficiently reproduce the effect of acidic water actually on the cement-based hardened body However, in the present invention, the sprinkling amount, flow velocity, water droplet diameter of the acidic water can be adjusted by using a watering nozzle and a pump so that the effect of the actual acidic water can be reproduced. During sprinkling, the adjusted acidic water was applied to the cured product at a constant concentration and in a constant amount. This makes it possible to change the color and surface roughness of the surface of the cured product in a short period of time, and to reproduce surface deterioration in a short period of time. According to the present invention, when simulating rain as acidic water, the amount of water spray is adjusted so that the size and speed of water droplets do not exceed the actual water droplet diameter (maximum 6 mm) and speed (maximum approximately 9 m / sec). The test time can be shortened by increasing the amount as much as possible, and the watering of acidified water to the hardened cement can be accelerated by repeating repeated watering after a certain drying time, rather than by continuous watering. large.

The materials which can be evaluated in the present invention include concrete, mortar, paste cement as a hardening material, and a surface modified and coated with an inorganic compound such as an alkali metal silicate based on these materials. And those coated with a water repellent such as alkylalkoxylan.

[0017]

Embodiments of the present invention will be described below. As shown in FIG. 1, acidic water 4 having a pH of 3.5 ± 0.1 was accumulated on the surface of a concrete specimen 1 so that a constant amount of acidic water 4 having a constant concentration of 3.5 could be sprinkled per hour. A tank 2 was provided, and a pump 3 and a spray nozzle 5 capable of pumping up and spraying water from the tank 2 by a predetermined amount were provided, and water was sprayed on a test body 1 supported above a drain receiver 6. Regarding the size of the water droplet used for watering, the watering amount was 1500 mm in terms of precipitation per hour. One sprinkling of acidic water was performed for 30 minutes, and drying was performed for the next 30 minutes. This was repeated 10 times. The experiment was performed at a temperature of 20.
The test was performed in an environment at 60 ° C. and a humidity of 60%. Table 1 shows the materials and compositions of the concrete used in the experiment.

[0018]

[Table 1]

Table 2 shows a change in surface color and a change in surface roughness before and after spraying the acidic water.

[0020]

[Table 2]

The color of the surface is measured by a device capable of displaying CIE L * a * b *, and the surface roughness is measured according to JIS B 0651.
It measured with the apparatus according to. Depending on the type of concrete, the surface color and surface roughness changed greatly before and after watering, the surface color changed significantly but the change in roughness was small, and the surface roughness changed greatly but the color changed. Some of them had little change, and some had little change in surface color and surface roughness.
It is considered that the change in color indicates a change in the surface composition, and the change in surface roughness indicates a change in the surface structure.There are differences in the composition and structure of the surface depending on the concrete mix and material type. It is considered that such a difference occurs.

From this fact, it is possible to add pH 3.5 to concrete.
The acidity of concrete is accelerated by repeating the process of sprinkling and drying the acidic water at a constant rate and drying, and measuring the color and roughness of the surface before and after the accelerated deterioration of the concrete to reduce the resistance of the concrete to acid rain Was evaluated in a short period of time. Next, as shown in FIG.
The acidic water 4 sprinkled from the nozzle 5 was once applied to an acidic water concentrating plate disposed in front thereof, and the acidic water 4 was concentrated. The amount of acidic water 4 is pump 3
And the width of the water outlet 7a of the acidic water concentration plate 7 are adjusted. The momentum of the flow of the acidic water 4 naturally changes depending on the amount of water. The angle of the test piece 1 was made closer to the vertical to simulate the case where rain would concentrate on the roof and flow on the wall.

Table 3 shows the change in surface color and the change in surface roughness before and after spraying the acidic water.

[0024]

[Table 3]

When the width 7a of the outlet of the water is set to be larger than that of the test piece 1 and the amount of the water is set to be larger, it is possible to simulate the case where there is a seawall concrete or the like of a river through which the acidic water flows. Further, as shown in FIG. 3, by adjusting the drop height H of the acidic water 4 from the acidic water concentration plate 7, the load of the acidic water 4 on the surface of the specimen 1 is changed, and the angle of the specimen 1 is changed. It simulated the case where the concrete floor was locally exposed to acidic water by approaching horizontally.

Table 4 shows a change in surface color and a change in surface roughness before and after spraying the acidic water.

[0027]

[Table 4]

However, in the case of the simulation of the wall surface and the simulation of the floor surface described above, the amount of the acidic water 4 per unit time required for the concrete test piece 1 was adjusted so as to be twice the amount of the water spray method. Furthermore, in order to make the total amount of the acidic water 4 at the time of the test of the water spray method, the wall surface simulation, and the floor surface simulation the same, the acid water 4 was poured for 30 minutes and the drying was performed for 30 minutes. Five times, half. In the case of floor simulation, the drop height H of the concrete test piece 1 and the acidic water concentration plate 7 is 1 m.

The above Tables 2 to 4 are summarized in Table 5.

[0030]

[Table 5]

From this, it is considered that the change in the surface roughness is a result of the decomposition, elution, and outflow of the cement hydrate caused by the influence of the combination of the acid properties of the acidic water and the physical force. Therefore, it is considered that the influence of the acid is small because the total amount of the acidic water is made the same, and it is considered that the difference in the influence of the physical force appears as a result. Further, in the case of concrete having a weak surface structure (deterioration is likely to progress), it is presumed that once the surface is deteriorated and the roughness is increased, the surface area affected by the acidic water is increased, so that the surface is further roughened.
(Concrete of Formulations 1 and 4 are susceptible to physical force.) It is considered that the change in color is less affected by physical force than the change in roughness. Also, as in the case of simulating a floor surface, if the physical quantity increases, the cement hydrate itself that has changed color may flow out, so the color change is not necessarily proportional to the physical quantity. .

Although there are differences in the amount of change in the surface roughness and the change in color depending on the test method, it is considered that the amount of change does not reverse by the combination. From the above results,
Even if the same amount of acid water is used, the method of concentrating the acid water and adding physical force results in a larger change in the color and roughness of the concrete than the method of sprinkling acid water simulating rain. You can see that. Therefore, in order to reproduce the effect of acidic water on concrete in a building, it is necessary to change the test method depending on the site and conditions such as when the water gathers on the roof and hits the concrete floor as a large block of water. Is possible.

[0033]

The present invention is configured as described above.
The following effects are obtained. The degradation of hardened cement and the products coated on the surface of these hardened materials due to not only acid rain but also acidic water can be reproduced by simulating the natural state, and the surface color change and surface roughness characteristic of cement deterioration Since the change in the hardness is measured, the resistance of the hardened cement body surface to the acidic water can be accurately evaluated in a short period of time.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view for explaining a method of a method for testing the deterioration of a cement-based cured product surface with acidic water according to the present invention.

FIG. 2 is a view for explaining the procedure of a method for testing the deterioration of a cement-based cured product surface with acidic water according to the present invention.

FIG. 3 is a view for explaining the procedure of a method for testing the deterioration of a cement-based cured product surface with acidic water according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Specimen 2 Tank 3 Pump 4 Acid water 5 Spray nozzle 6 Drain receiver 7 Acid water concentration board 7a Water outlet

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenro Mitsui 1-5-1, Otsuka, Inzai City, Chiba Pref. No. 1 Inside Takenaka Civil Engineering Tokyo Head Office

Claims (2)

[Claims] 1. A method of spraying a fixed amount of acidic water at a constant concentration per hour to simulate a mode in which rain falls on the surface of a cement-based cured product of concrete, mortar, paste and a product coated on the surface of the cured product. Sprinkling water through a nozzle, and also simulating the manner in which rain flows along the roof and then flows on the wall, and then concentrates the watering through a concentrating plate, and then hits the surface of the product approaching a vertical position, Furthermore, simulating a mode in which the concentrated rain falls locally on the floor in a waterfall shape, the water sprinkling is concentrated through the concentrating plate, and then applied to the surface of the product approaching a horizontal posture under a predetermined drop height setting. Add the process repeatedly with a certain drying time,
Thereafter, by measuring the change in color and surface roughness of the product surface, the resistance of the surface of the hardened cement to the acidic water was evaluated to evaluate the deterioration of the hardened cementitious surface by the acidic water. Test method. 2. The acidic water tank and the amount of sprinkling of the acidic water, the flow velocity,
An acid water sprinkler system consisting of a pump and a spray nozzle that adjusts the water droplet diameter and adjusts the amount, flow rate, and water content of the acidic water at a constant concentration and constant amount during the water sprinkling. An apparatus for testing deterioration of a cement-based hardened material surface with acidic water, comprising the spray nozzle and an acidic water concentration plate disposed at a predetermined height in front of the spray nozzle.