Setting retarder and concrete placing joint processing method using the same
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TODA CORP
- Filing Date
- 2025-11-17
- Publication Date
- 2026-07-02
AI Technical Summary
Conventional concrete joint treatment methods are labor-intensive, time-consuming, and inefficient, and often require waiting for concrete to harden, leading to increased costs and reduced productivity, while also posing environmental and human health risks due to the use of non-naturally derived substances.
A setting retarder containing a gelling component, such as pectin, which reacts with calcium in concrete to form a gel, is sprayed on the surface to delay setting and prevent runoff, allowing immediate application without waiting for bleeding water to subside, ensuring effective coverage even on inclined surfaces.
The use of a setting retarder with a gelling component reduces labor, shortens the process, improves productivity, and minimizes environmental and human health impacts by using naturally derived pectin, which forms a gel to maintain the setting retarder's effect and allows efficient exposure of coarse aggregates.
Smart Images
Figure JP2025040055_02072026_PF_FP_ABST
Abstract
Description
Setting retarder and concrete joint treatment method using the same
[0001] The present invention relates to a setting retarder having a gelling action in addition to a setting retardation action and a concrete joint treatment method using the same.
[0002] Conventionally, when constructing a large-scale concrete structure in civil engineering work or the like, concrete is sequentially placed in layers. At this time, when the placement of concrete for one day is completed, the placement of concrete will be resumed across dates. Therefore, the treatment of the interface (joint) between the placed concrete and the new concrete is important for ensuring the quality of the concrete.
[0003] The following are known as conventional joint treatment methods. (1) Treatment method using high-pressure water: As disclosed in Patent Document 1 below, after the placed concrete reaches the required hardness, the vulnerable part on the concrete surface is removed with high-pressure water, leaving only the sound concrete surface to obtain a good joint surface. (2) Treatment method using a setting retarder: As disclosed in Patent Document 2 below, a setting retarder is sprayed on the joint surface of the concrete to delay the hardening of the surface layer, and then the unhardened concrete is removed with high-pressure water to expose the sound concrete surface. (3) Treatment method by chipping: As disclosed in Patent Document 3 below, after the concrete is solidified, mechanical treatment such as cutting or impact is applied to the concrete surface to form unevenness. (4) Treatment method using a joint treatment agent: As disclosed in Patent Document 4 below, after the concrete is placed, a polymer emulsion type adhesive is sprayed on the concrete surface while the bleeding water gushing out on the concrete surface is absorbed into the concrete, and then new concrete is placed on the concrete surface to make a joint. (5) Treatment method using a thickening setting retarder: As disclosed in Patent Document 5 below, it is a treatment method using a thickening setting retarder composed of a compound A having a setting retardation action and a compound B which is a thickener of an alkali thickening type whose aqueous solution viscosity increases in an alkaline environment.
[0004] JP 11-280260, JP 4-222771, JP 2-47469, JP 54-18124, JP 2022-176723
[0005] However, the above conventional joint treatment methods had the following problems: (1) Treatment method using high-pressure water: It was necessary to wait until the poured concrete hardened to a predetermined state so that the concrete surface layer of the appropriate thickness could be removed with high-pressure water. This waiting time resulted in increased labor costs, longer process times, and decreased productivity. Also, if the waiting time was too short, the coarse aggregate would loosen, and if the waiting time was too long, it would be difficult to expose the coarse aggregate, so it was necessary to determine the optimal waiting time. (2) Treatment method using setting retarder: The sprayed setting retarder may be diluted by bleeding water or run off on slopes, preventing it from achieving the expected effect. To mitigate the effects of bleeding water, it was necessary to wait until the bleeding subsided before spraying, and this waiting time was a factor that reduced work efficiency. (3) Treatment method using chipping: When applying mechanical treatment to the concrete surface, it was necessary to do so carefully so as not to loosen the coarse aggregate, and the occurrence of fine cracks had been pointed out. (4) Treatment method using construction joint treatment agent: Since the expected effect may not be obtained even if construction joint treatment agent is used without proper consideration, it was necessary to confirm the application method, timing and amount to be applied with the concrete to be used in advance before using it. (5) Treatment method using thickening setting retarder: In the treatment method described in Patent Document 5 above, an alkali swelling polymer is used as a thickening agent, but since most polymer materials do not decompose in the natural environment, it is preferable to reduce the burden on humans and the environment by using naturally derived components as much as possible, even for substances that are sprayed on concrete.
[0006] Therefore, the main objective of the present invention is to provide a setting retarder and a concrete setting retarder method using the same, which reduce the labor, shorten the process, and improve productivity of concrete jointing work, while also reducing the human and environmental burden by using naturally derived components.
[0007] To solve the aforementioned problems, the present invention according to claim 1 provides a setting retarder that is sprayed on the surface of concrete at a concrete construction joint, wherein the setting retarder comprises a setting retarder component and a gelling component, and the gelling component is pectin which reacts with calcium in the concrete to form a gel.
[0008] In the invention described in claim 1 above, a setting retarder containing a gelling component in addition to a setting retarder component is used as a setting retarder to be sprayed on the surface of the poured concrete at the concrete joint. The gelling component used is pectin, which reacts with calcium in the concrete to form a gel. Since this pectin reacts with calcium in the concrete to form a gel immediately after spraying, there is no need to wait for the bleeding water to subside, and it is possible to spray it on the concrete surface without delay after concrete pouring. Furthermore, because the setting retarder contains a gelling component, the setting retarder component does not flow out even on inclined surfaces or uneven areas, and the setting retarder effect can be sustained for a long period of time. Therefore, it is possible to reduce labor, shorten the process, and improve productivity in the concrete joint treatment work.
[0009] Furthermore, since pectin, which constitutes the gelling component, is a plant-derived polysaccharide and is also used as a food additive, even if it were to scatter during spraying or wash out, the human and environmental burden is considered to be extremely low.
[0010] As part of the present invention according to claim 2, the coagulation retarder according to claim 1 is provided, wherein the pectin is LM pectin.
[0011] In the invention described in claim 2 above, LM pectin is used as the pectin constituting the gelling component. LM pectin is a type of pectin that has the property of gelling with minerals such as calcium, and it reacts with calcium in concrete to produce a gel.
[0012] As part of the present invention according to claim 3, the coagulation retarder according to claim 1 is provided, wherein the pectin is HM pectin.
[0013] In the invention described in claim 3 above, HM pectin is used as the pectin constituting the gelling component. HM pectin reacts with the alkali in concrete to change into LMA pectin, and like LM pectin, reacts with calcium in concrete to produce a gel.
[0014] As part of the present invention according to claim 4, the present invention provides a setting retarder according to claim 1, wherein the setting retarder contains a coloring agent.
[0015] In the invention described in claim 4 above, by including a coloring agent in the setting retarder, the areas that have been sprayed can be clearly identified when the agent is sprayed on the surface of concrete, and the spraying work of the setting retarder can be made more efficient.
[0016] As part of the present invention according to claim 5, a concrete joint treatment method is provided that uses a setting retarder as described in any of claims 1 to 4, comprising: a first step of spraying the setting retarder onto the surface of the placed concrete; a second step of removing the unhardened surface concrete with high-pressure water after a predetermined time has elapsed to expose the coarse aggregate; and a third step of placing concrete on the surface.
[0017] In the invention described in claim 5 above, after spraying the setting retarder on the surface of the poured concrete, the coarse aggregate is exposed by washing away the unhardened surface concrete with high-pressure water the following day, or on Monday if the concrete is poured on Friday, and then pouring concrete onto that surface. In this way, since the setting retarder can be sprayed without waiting for the bleeding water to subside after concrete pouring, it is possible to reduce labor in the joint treatment work, shorten the process, and improve productivity.
[0018] As described in detail above, the present invention makes it possible to reduce labor, shorten the process, and improve productivity in jointing work, and also reduces human and environmental burdens by using naturally derived components.
[0019] This is a schematic diagram showing the component composition of the setting retarder 1 according to the present invention. This is a concrete cross-sectional view relating to the concrete joint treatment method according to the present invention. This is a procedure diagram (1) of the concrete joint treatment method. This is a procedure diagram (2) of the concrete joint treatment method. This is a procedure diagram (3) of the concrete joint treatment method.
[0020] Embodiments of the present invention will be described in detail below with reference to the drawings.
[0021] [Setting retarder] The setting retarder according to the present invention, when sprinkled on the surface of the concrete at the concrete joint, slows down the cement hydration reaction in the surface layer of the concrete sprinkled on it, thereby extending the time required for setting.
[0022] As shown in Figure 1, the setting retarder 1 is composed of a setting retarder component 2 and a gelling component 3. In other words, the setting retarder 1 according to the present invention is characterized by containing a gelling component 3 that gels the sprayed setting retarder 1, in addition to the setting retarder component 2 that is present in ordinary setting retarders. As a result, the surface layer of concrete to which the setting retarder 1 has been sprayed becomes covered with the gelled setting retarder 1.
[0023] The aforementioned coagulation retardant component 2 can be any of the commonly used coagulation retardants without limitation, such as oxycarboxylic acids (gluconic acid, glucoheptonic acid, citric acid, tartaric acid) and their salts, keto acids (2-ketocarboxylic acid) and their salts, aminocarboxylic acids (glutamic acid) and their salts, sugars, sugar alcohols, high molecular weight organic acids (ligninsulfonic acid, humic acid, tannic acid) and their salts, water-soluble acrylic acids (polyacrylic acid) and their salts, silicic acid fluorides, boric acids, phosphates, zinc compounds, lead compounds, copper compounds, etc. In particular, it is preferable to use general-purpose sodium gluconate.
[0024] The setting delay time provided by setting delay component 2 should preferably be such that it is 12 to 96 hours, and the amount added should be such that it is sufficient to ensure this delay. This allows the processing work to be carried out the day after concrete placement, or on Monday if placement is on Friday, or on Tuesday or later if Monday is a holiday.
[0025] The addition rate of the setting retarder component 2 is preferably determined based on the criterion that the penetration resistance of the gelled surface layer of the concrete layer to which the setting retarder 1 has been applied can be removed by washing with high-pressure water. Therefore, it is desirable to control the setting retarder 1 after concrete placement, after a predetermined time has elapsed, so that the penetration resistance of the gelled surface layer becomes less than or equal to a predetermined value that can be removed by washing with high-pressure water.
[0026] In order to control the penetration resistance of the surface layer of concrete that has been gelled by applying the setting retarder 1 so that it is below a value that can be removed by washing, it is desirable to conduct laboratory tests in advance and obtain a graph showing the relationship between the time it takes to obtain a predetermined penetration resistance value and the setting retarder component 2 to be used. By obtaining such a graph, it becomes possible to easily determine the addition rate of the setting retarder component 2 even if the time until washing changes. The penetration resistance value can be measured according to the setting time test method for concrete, JIS A 1147.
[0027] The gelling component 3 is calcium (Ca) in concrete. ２＋ Pectin that gels upon reaction with galacturonic acid is used. This pectin is a complex polysaccharide found in the cell walls and mid-leaves of plants, and consists of galacturonic acid and polygalacturonic acid, in which galacturonic acid methyl esters, which are formed by methyl esterification of a portion of the galacturonic acid, are linked by α-1,4 bonds. The structure of pectin can be broadly classified into two types based on the ratio of galacturonic acid to galacturonic acid methyl ester. Pectin with a proportion of galacturonic acid methyl ester in the total pectin molecule (degree of esterification DE) of 50% or more is called HM pectin, and pectin with a DE of less than 50% is called LM pectin. Generally, naturally occurring pectin is HM pectin, and LM pectin is produced by de-esterifying it. LM pectin is classified into LMA pectin (alkali-treated type) and LMC pectin (acid-treated type) depending on the treatment method.
[0028] The aforementioned LM pectin is water-soluble, and gelation occurs through ionic bonding between calcium and carboxyl groups. The lower the DE, the more carboxyl groups react with calcium, thus increasing its reactivity to calcium.
[0029] The aforementioned HM pectin undergoes de-esterification treatment in an alkaline environment, transforming into LMA pectin. The transformed LMA pectin, like the aforementioned LM pectin, is water-soluble, and gelation occurs through ionic bonding between calcium and carboxyl groups. The lower the DE (Dihydrogen Efficiency), the more carboxyl groups react with calcium, resulting in higher reactivity with calcium.
[0030] The pectin, which is in powder form, is dissolved in water and sprayed onto the concrete surface as an aqueous solution. The aqueous solution of the setting retarder component 2 and the aqueous solution of the gelling component 3 may be sprayed separately, but since there is no problem with compatibility even if the setting retarder component 2 and the gelling component 3 are liquefied together, spraying an aqueous solution containing both onto the concrete surface can reduce labor and shorten the procedure.
[0031] When LM pectin is used as the gelling component 3, after being sprayed onto the concrete surface, it quickly reacts with the calcium in the surface layer of the concrete to immediately form a gel.
[0032] When HM pectin is used as the gelling component 3, it reacts with the alkali in the concrete, causing a reaction similar to that of de-esterification alkali treatment of HM pectin, and the HM pectin is converted to LMA pectin. The converted LMA pectin reacts with calcium in the concrete to immediately form a gel.
[0033] The amount of gelling component 3 added is determined considering the height at which the coarse aggregate is adequately exposed by washing away the gelled surface layer of the concrete. A specific amount of gelling component 3 added is preferably 0.1 to 20%.
[0034] Furthermore, as mentioned above, the degree of esterification DE of gelling component 3 is determined by considering the degree of slope and unevenness of the area to be constructed, as a lower degree of esterification DE results in stronger gelling power.
[0035] Thus, by spraying the setting retarder 1 containing the gelling component 3, the surface layer of the concrete gels, preventing dilution of the setting retarder component due to bleeding, ensuring that the effect of the setting retarder component 2 is reliably sustained. Furthermore, even if the concrete placement surface is sloped or uneven, a gelling layer is formed along the sloped or uneven surface, preventing the outflow of the setting retarder component 2 and ensuring that the effect of the setting retarder component 2 is reliably exerted.
[0036] Furthermore, the aqueous solution of the setting retarder 1 before application has low viscosity and is easy to handle, thus facilitating the application process.
[0037] Since the aforementioned pectin is a plant-derived ingredient also used as a food additive, even if workers accidentally inhale it or it gets into their eyes or mouth, the impact on the human body is extremely low. Furthermore, even if it leaks into the natural environment during spraying or washing, it decomposes naturally over a long period of time, resulting in an extremely low environmental burden.
[0038] The setting retarder 1 may contain a coloring agent so that the area where it has been applied can be clearly identified when it is sprayed on the surface of concrete. Any known coloring agent can be used without limitation, but from the viewpoint of keeping human and environmental burdens to a minimum, it is preferable to use natural coloring agents derived from plants and animals. Examples of such natural coloring agents include squid ink pigment, turmeric pigment, cocoa pigment, gardenia pigment, saffron pigment, spirulina pigment, chili pepper pigment, red yeast rice pigment, grape skin pigment, and safflower pigment.
[0039] [Method for treating concrete joints] Next, a method for treating concrete joints using the setting retarder 1 described above will be explained. The concrete joint treatment method according to the present invention is a method for treating construction joints that occur during the placement of concrete when concrete is placed in layers sequentially upwards, as shown in Figure 2, and specifically follows the procedure below. The same procedure can also be used when concrete is placed in layers sequentially in an oblique or horizontal direction.
[0040] (First step) In the first step, as shown in Figure 3, after pouring the final layer of concrete on the lower side leading to the construction joint surface 10, the setting retarder 1 is sprinkled on the surface of the poured concrete 11.
[0041] In the concrete pouring procedure, the concrete pouring schedule is determined in advance, taking into account the daily concrete pouring capacity based on the size and shape of the structure.
[0042] Since concrete pouring work is usually carried out while compacting with a vibrator, it is common practice to pour the concrete in two or more layers to reach a total height each day. In this case, the height of each concrete layer is determined considering the compaction capacity, but the standard height h1 of each concrete layer is 40 to 50 cm or less.
[0043] The type of cement used for concrete is not particularly limited, and various Portland cements such as ordinary Portland cement, rapid hardening Portland cement, ultra-rapid hardening Portland cement, moderate heat Portland cement, white Portland cement, sulfate resistant Portland cement, low heat Portland cement, etc., and blended cements such as blast furnace slag cement, fly ash cement, silica cement, etc. can be used. In addition, it is desirable to use general water reducing agents, high performance water reducing agents, and high performance AE water reducing agents such as lignin sulfonate type, polyol type, and oxycarboxylate type. Among them, high performance water reducing agents such as polyalkyl allyl sulfonate type and melamine resin sulfonate type with a large water reducing rate, and polycarboxylate type high performance AE water reducing agents are preferred. In the figure, reinforcement bars, formwork, etc. are not shown, and only the concrete part is shown.
[0044] The spraying of the setting retarder 1 can be carried out immediately without delay after the placement of the concrete in the final layer. The spraying of the conventional setting retarder is carried out after waiting for the bleeding to converge in order to prevent the setting retardation effect of the setting retarder from being reduced due to dilution by the bleeding water. The waiting time at this time increased labor costs, prolonged the process, and was a factor in reducing productivity. However, in the setting retarder 1 according to the present invention, since it gels due to the gelling component 3, dilution of the components by the bleeding water hardly occurs, and problems such as those of the conventional setting retarder do not occur.
[0045] In addition, after the placement of the concrete in the final layer, since there is no need for the waiting time before spraying the setting retarder and the subsequent treatment as in the conventional case, by spraying the setting retarder 1 after the placement of the concrete in the final layer, the work for the day is completed and there is no overtime, resulting in suppression of labor costs and improvement of productivity.
[0046] (Second step) In the second step, after a predetermined time has elapsed, that is, after the time of the joint interval has elapsed, as shown in FIG. 3, the unhardened concrete on the surface layer is removed with high-pressure water 12, and a washout is performed to expose the coarse aggregate.
[0047] The joint pouring interval can be set to the day after the final layer of concrete is poured, or in the case of pouring on Friday, it can be set to Monday or Tuesday of the following week. Therefore, it can contribute to a two-day weekend with Saturdays and Sundays off.
[0048] Washing out is carried out by spraying on the surface of the concrete and removing the fragile uncured concrete whose setting has been delayed by the setting retarder 1 gelled by the gelling component 3 and the setting retardation component 2 of the setting retarder 1 with high-pressure water 12. By this washing out, a part of the coarse aggregate is exposed, and unevenness is formed on the surface of the concrete. This uneven surface becomes the new joint surface 13.
[0049] (Third procedure) In the third procedure, concrete 14 is poured on the new joint surface 13 exposed by washing out, and the concrete 14 is sequentially stacked layer by layer upward toward the upper layer side. The height h2 of one layer of the concrete 14 injection is set to a standard of 40 to 50 cm or less.
[0050] 1... Setting retarder, 2... Setting retardation component, 3... Gelling component, 10... Joint surface, 11... Concrete, 12... High-pressure water, 13... New joint surface, 14... Concrete
Claims
1. A setting retarder that is sprayed on the surface of concrete at a concrete construction joint, wherein the setting retarder comprises a setting retarding component and a gelling component, and the gelling component is pectin that reacts with calcium in the concrete to form a gel.
2. The coagulation retarder according to claim 1, wherein the pectin is LM pectin.
3. The coagulation retarder according to claim 1, wherein the pectin is HM pectin.
4. The setting retarder according to claim 1, wherein the setting retarder contains a coloring agent.
5. A concrete joint treatment method using a setting retarder as described in any of claims 1 to 4, comprising: a first step of spraying the setting retarder onto the surface of the placed concrete; a second step of removing the unhardened surface concrete with high-pressure water after a predetermined time has elapsed to expose the coarse aggregate; and a third step of placing concrete onto the surface.