JPS596278B2 - concrete cleaning agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a concrete cleaning agent used for removing dirt from concrete surfaces and concrete adhering to concrete products, concrete equipment, and the like.

The surface of concrete becomes dirty primarily due to iron rust and wood scum from the formwork used during concrete molding or pouring, and secondarily due to efflorescence caused by rainwater after the concrete hardens, and stains from steel frames and reinforcing bars. Dirt is caused by rust runoff, pollutants leaching from the soil, or adhesion of airborne pollutants.

Conventionally, these stains were removed and cleaned using only hydrochloric acid, but
Hydrochloric acid alone reacts rapidly with the cement and calcium carbonate aggregate in concrete, generating a large amount of bubbles on the concrete surface, trapping the hydrochloric acid in the bubbles, reducing its cleaning function, and causing damage to the concrete surface Because a chloride layer forms on the surface, hydrochloric acid does not penetrate inside, resulting in poor cleaning performance.

Further, even after washing, a large amount of hydrochloric acid remains in the generated chloride, so it must be neutralized with an alkaline solution such as caustic soda. On the other hand, when cleaning and removing excess concrete adhering to concrete equipment such as concrete mixers, formwork, and construction equipment, as well as secondary concrete products such as concrete piles, balls, and blocks, the above-mentioned method can be used to treat with hydrochloric acid alone. In addition to similar problems, it also has the major drawback of significantly corroding the metal base of the equipment.

In order to improve these drawbacks of using only hydrochloric acid, the present inventor conducted various studies and found that adding a phosphate ester or (and) borate ester surfactant to hydrochloric acid has an excellent cleaning effect. In addition, by not corroding the metal substrate to which concrete is attached, and by adding an organic acid to the mixed solution, the corrosion inhibition effect can be dramatically improved without impairing the cleaning effect on concrete. The present invention provides a concrete cleaning agent made by adding a phosphoric acid ester or (and) a boric acid ester surfactant to hydrochloric acid, and an organic acid added thereto as necessary. It was developed for the purpose of providing a concrete cleaning agent made of

The phosphate ester surfactant used in this invention is a compound having the following general formula. RO-[CH2CH2O
] n0 \ 7 / \ (n is the average number of added moles of ethylene oxide, R is the number of carbon atoms 8 to
(30 alkyl groups or alkyl phenyl groups) The boric acid surfactant used in this invention is a compound having the following general formula.

The concrete cleaning agent according to the present invention is useful for removing cast concrete, mortar, concrete [■■ Iron rust, efflorescence, and stains caused by exhaust gas, and for removing excess dirt adhering to secondary concrete products, formwork, concrete mixing/transporting equipment, etc. These are used for concrete removal, and the results of various experiments on these will be explained below.

[Experimental example 1] Stain cleaning test The cleaning solution used was a mixture of hydrochloric acid (HCl = 35% or more), a first-class reagent, and phosphoric acid esters, such as monoester, diester, and a trace amount of triester, with a phosphorus content of 3.
．． 6% or polyoxyethylene glycerol borate was added as a boric acid ester, and for comparison, hydrochloric acid alone was also used.

The object to be cleaned is cement/sand = 1/3, water-cement ratio -70
It was molded into a size of 30 x 30 x 2.5 CfL using white cement mortar using akansuite with a particle size of 1.2 to 2.5 mm.

In order to forcibly adhere dirt, the mold was subjected to the following treatment when molding this mortar. In the case of wood stains, red oak broth was applied to the plywood formwork, and in the case of iron rust stains, a 1% calcium chloride aqueous solution was applied to the steel formwork and left for one day to allow rust to develop. This mortar was demolded after 2 days of wet curing (20°C, RH = 80% or more), dried for 5 days (20°C, RH = 50%), and then used for testing.
In the cleaning test, the cleaning solution was adjusted to undiluted solution, 2-fold diluted solution, and 4-fold diluted solution with water, and then placed in a polyethylene cleaning pin.
Surface of the object to be cleaned placed vertically (formwork surface with dirt)
After one hour, the surface was washed with water and visually observed to determine the cleaning effect.

The results are shown in Table 1. As is clear from Table 1, by adding a small amount of phosphoric acid ester or boric acid ester to hydrochloric acid, the cleaning effect was superior to when hydrochloric acid was used alone.

Visual observation during cleaning also showed that when these esters were added, the bubbles that were generated disappeared more quickly and cleaning was improved. Also, do not leave it unattended after washing with water.
When washed with only hydrochloric acid and hydrochloric acid, efflorescence occurred, but when these esters were added and washed, no abnormality was observed. [Experimental Example 2] Deconcrete on iron plate and erosion test on iron plate The cleaning liquid used was a mixture of hydrochloric acid (HCl 35% or more), a first class reagent, and senoester, diester, and a trace amount of triester as phosphoric acid ester, and had a phosphorus content of 5. 8% or polyoxyethylene glycerol borate oleate as a boric acid ester, and oxalic acid as an organic acid as a corrosion inhibitor for iron plates were separately prepared.

The addition ratio of each (is shown in Table 2. For comparison, the case where it is used only for hydrochloric acid is also shown. The object to be cleaned is 100%
×25×311 mild steel plate with ordinary Portland cement:
It was immersed in a mortar-water paste of No. 6 silica sand - 1:2, water-cement ratio = 65%, immediately pulled up to adhere mortar, and left to harden for 2 days before being used for testing.

In the test, 500cc of each cleaning solution was placed in a beaker, the object to be cleaned was immersed in it, and after 1 hour, the gas from the mortar that had been washed away was removed, and the change in thickness of the mild steel plate over time was read to a limit of 1/100u. The thickness was measured using a dial gauge type thickness meter.

The results are shown in the attached figure (graph). In this graph, measurements were started after the adhering concrete was completely removed (the required time was 1 hour after immersion). As is clear from this figure, the degree of corrosion of the mild steel plate is smaller when treated with a small amount of phosphate or boric acid than when treated with just hydrochloric acid, and when oxalic acid is added, there is almost no corrosion. This was recognized.

Separately, sulfonic acid esters may be used instead of or in addition to phosphoric acid esters and boric acid esters as ester surfactants, and formic acid, acetic acid, acrylic acid, benzoic acid may be used instead of or in addition to oxalic acid as organic acids. When a stain cleaning test and an iron plate erosion test were conducted using the same method, almost the same results as above were obtained.

Next, examples of the concrete cleaning agent according to the present invention will be described in detail.

Example 1 Removing stains from concrete products (1) When cleaning the surface of reinforced concrete columns (TEPCO specification 13-50) erected in a factory area that were discolored due to iron rust and adhesion of contaminants, industrial hydrochloric acid was used. (3
5% or more), 1 part by weight of phosphoric acid ester with phosphorus content of 3.6%, 1 part by weight of oxalic acid, and 8 parts by weight of water, and this was further doubled with water. trigram and 3
The solution was diluted twice as much, poured into a polyethylene washing bottle, and sprinkled on the concrete surface. After waiting for a reaction with the discoloration substance on the surface, the solution was washed away with water.

For comparison, 2-fold and 3-fold dilutions of hydrochloric acid were also carried out. The results showed that with this cleaning agent, most of the stains were removed with a 3-fold dilution, and the stains were completely removed with a 2-fold dilution, whereas in the case of simple hydrochloric acid, a 2-fold dilution was 3 times the amount of this cleaning agent. It was the same as the diluted solution, and the 3 times diluted solution left a thin layer of dirt.
Furthermore, efflorescence occurred on the surface after cleaning when using only hydrochloric acid, but no efflorescence was observed when this cleaning agent was used. In addition, to investigate the neutralization of concrete after cleaning with this cleaning agent, phenolpthalene solution was sprayed on the fractured surface of the concrete, but only the surface was neutralized, but no progress into the interior was observed. (2) The tar-like dirt that had flowed out from the soil and had adhered to the wall of the Spritton Interlock Block for earth retaining was sprayed with a cleaning agent with the same composition as in (1) above as a undiluted solution, and as a result, it was removed with hydrochloric acid alone. I was able to cleanly remove anything that could not be removed.

In addition, stains caused by exhaust gas adhering to the surface of beaten-up decorative mortar and white cement sculptures displayed outdoors were also cleaned with a twice-diluted solution of the same composition as in (1) above, and with only hydrochloric acid. I was able to remove it more cleanly than in the case.

Example 2 Removes wood scum and iron stains from poured concrete.White When cleaning wood scum stains caused by mold marks on the surface of poured concrete and iron rust stains that have flowed out from steel frames, use industrial hydrochloric acid (35% or more) 80% 1 part, 2 parts of polyoxyerylene glycerol borate stearate, 0 parts of acetic acid
．． Prepare a cleaning agent at a ratio of 1 part water and 17.9 parts water (all parts by weight), dilute this 3 times with water, pour it into a polyethylene cleaning pin, sprinkle it on the concrete surface, and then apply it to the surface. I waited for the reaction with the discolored substance and washed it off with water.

As a result, this cleaning agent was able to remove stains significantly more cleanly than hydrochloric acid alone.

Three other experiments were conducted using the same method, and similar results were obtained.

Example 3 Removal of concrete attached to metal mold work A normal cement concrete specimen for compression test was molded, and after 1 day, the mold work (inner dimensions 10 x 10 x 40 cm) with the demolded concrete still attached was cleaned. When cleaning, a cleaning agent prepared in the ratio of 70 parts of industrial hydrochloric acid (concentration 35% or more), 0.5 parts of dibasic acid sodium dialkyl sulfosuccinate, 3 parts of benzoic acid, and 26.5 parts of water was mixed with water. The mold was completely immersed in a solution diluted twice as much as the mold, and after one hour, the mold was taken out and tap water was sprayed on it.The adhering concrete could be completely removed without eroding the mold.

For comparison, when cleaning with the above-mentioned industrial hydrochloric acid alone, the adhering concrete could not be completely removed, and there were areas where mold release oil remained and areas affected by hydrochloric acid were scattered on the iron base of the mold work. It was distributed. As mentioned above, according to the concrete cleaning agent of the present invention, since a phosphate ester or (and) a borate ester surfactant is added to hydrochloric acid, it has excellent antifoaming and antifoaming properties compared to hydrochloric acid alone. In addition to exhibiting permeability to concrete, unlike hydrochloric acid alone, it also exhibits the degreasing and cleaning effects of a surfactant, improving cleaning power, and even after cleaning, the surfactant's action allows it to be neutralized with alkali. In addition, these esters themselves have a corrosion inhibiting effect on metals, so they do not damage the iron base of concrete equipment and also reduce the fatigue of the cleaning solution itself.
÷Ma〉Naro 8 θ) 1 喀 4 仝To 2 ``r d 1 shi) ra K5 A + ★ Na ζ It has an industrial effect, and when an organic acid is added, it also prevents corrosion of metals. Its industrial effects are extremely large, such as the inhibitory effect being greatly improved.

[Brief explanation of the drawing]

Claims (1)

[Scope of Claims] 1. A concrete cleaning agent characterized by adding a phosphoric acid ester or (and) a boric acid ester surfactant to hydrochloric acid. 2. A concrete cleaning agent characterized by adding a phosphoric acid ester or (and) a boric acid ester surfactant and an organic acid to hydrochloric acid.