JPH0328395B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a method for producing a molded body using a lightweight mortar composition with controlled setting onset time and hardening rate. [Background of the Invention] In recent years, molded bodies such as panels have been manufactured by injecting lightweight mortar prepared using lightweight aggregate such as synthetic resin foam into a formwork and hardening it within the formwork. This is increasingly being used as a building material for partitions, exterior walls, etc. Methods for manufacturing such lightweight mortar molded bodies include pouring (injecting) a lightweight mortar mixture into multiple molds, then leaving the molds to stand and hardening, or by moving the molds while A commonly used method is to sequentially perform pouring, curing, and demolding. however,
Ordinary lightweight mortar generally does not harden to the extent that it can be removed from the mold unless it is poured into the mold and left in the mold for more than a day to fully cure. A storage area is required to store the formwork filled with mortar for a long period of time. In addition, in the latter continuous manufacturing method, considering the time it takes for the lightweight mortar to start setting and reach a hardened state that allows demolding, it is necessary to lengthen the total length of the process or increase the process speed. Need to slow down. However, increasing the total length of the process is disadvantageous because it requires a vast site and equipment, and it is also impractical to reduce the operating speed, so in reality, a lightweight mortar composition is poured. Methods such as removing the molds from the production line, stacking them, and leaving them to cure are used. That is, as long as ordinary lightweight mortar compositions were used, continuous production of lightweight mortar molded bodies was actually impossible. Therefore, we added a hardening accelerator mainly composed of calcium chloride to the lightweight mortar used for manufacturing such molded bodies, especially continuous molded bodies, to quickly develop the strength necessary for demolding. A method is used to do so. By adding this curing accelerator, the time from pouring to curing to the extent that demolding is possible is shortened to some extent, but the curing accelerating effect is insufficient with the normal addition amount, and it still takes a long time. The strength required for demolding will not develop until later. In order to improve the curing accelerating effect, it is possible to increase the amount of curing accelerator added, but increasing the amount of curing accelerator added reduces the final strength of the obtained molded product.
In addition, when using metal formwork or when producing molded objects with embedded reinforcing bars, it is important to add a large amount of the hardening accelerator mainly composed of chloride as described above. It can also cause rusting of reinforcing steel. For the reasons mentioned above, it is difficult to obtain satisfactory results when accelerating the curing of lightweight mortar using a curing accelerator. Another known method is a curing method in which lightweight mortar poured into a mold is brought into contact with steam or warm air at temperatures below 100°C to quickly develop strength. However, even with this method, a considerable amount of time is required until the strength necessary for demolding is achieved. Additionally, attempts have been made to add an accelerating agent such as water glass to the above-mentioned lightweight mortar. Addition of an quick-setting agent is an effective means for developing strength quickly, but on the other hand, there is a problem in that the time from the addition of the quick-setting agent to hardening is extremely short. That is, pour the mortar mixture into the formwork,
The mortar mixture must be in a state of low viscosity and high fluidity until the surface of the mortar mixture is smoothed using a plastering trowel, a ruler, etc. Since the added mortar kneaded material begins to harden in a short time, it is difficult to produce a lightweight mortar molded body with excellent internal uniformity and surface condition from such a mortar kneaded material. In other words, the lightweight mortar used in the mold manufacturing method using a mold exhibits good fluidity during pouring, and after pouring is completed and a smooth surface is obtained, setting and hardening proceeds rapidly. Therefore, it is preferable that the time required to reach complete curing is short. [Object of the invention] The object of the present invention is to provide a method for producing a lightweight mortar molded body that can adjust the setting start time and hardening speed to set the demolding time to a desired time with high reproducibility. shall be. [Summary of the Invention] The present invention comprises cement, synthetic resin foam particles in an amount of 1 to 5 times the volume of the cement, a dispersant,
A homogeneous aqueous kneaded product is prepared in advance by kneading a setting retarder in the range of 0.1 to 3% by weight based on the cement and water, and then 2 to 10% by weight based on the cement is added to the aqueous kneaded product. To provide a method for producing a lightweight mortar molded body, which comprises adding an quick-setting agent within the range of 100 to 100%, and then injecting the same into a mold, allowing it to solidify and harden, and removing the mold. That is, in the lightweight mortar using synthetic resin foam particles as a lightweight filler used in the present invention, additives having mutually contradictory properties, ie, a setting retarder and an accelerating agent, are mixed in the above-mentioned specific order. However, according to the research of the present inventor, these additives have different effects on each other in light mortar compositions. It turns out that it does not act in a negative way. That is, in the present invention, when preparing a lightweight mortar using synthetic resin foam particles as a lightweight filler, a setting retarder is first used, and a uniform slurry is formed together with cement and synthetic resin foam particles. Then, when an accelerating agent is added and mixed, the accelerating agent does not show any substantial effect until the mortar begins to set;
The setting retarder merely controls the time until the mortar starts setting, and does not substantially affect the hardening rate after setting starts. Therefore, in the present invention, when a molding operation using a mold is carried out using a lightweight mortar composition, since the time until the start of setting can be adjusted appropriately, it is possible to perform tasks such as pouring the mortar mixture and smoothing the surface. The process can be carried out over a sufficient period of time, while when the adjusted setting start time is reached, setting and hardening proceed quickly, making demolding possible in a short time. Therefore, continuous production of lightweight mortar molded bodies is possible, and the strength and surface condition of the resulting molded bodies are at the same level as conventional molded bodies manufactured over a long period of time. [Detailed Description of the Invention] In the present invention, the cement is not particularly limited and any commonly used cement can be used. Examples of cement that can be used include ordinary Portland cement, early strength Portland cement, blast furnace cement, and flyer cement. Examples include Tsushiyu cement. The lightweight mortar used in the present invention must contain synthetic resin foam particles in an amount of 1 to 5 times the volume of the above-mentioned cement. There are no particular limitations on the synthetic resin foam particles used. Examples of the synthetic resin foam particles used include expanded polystyrene particles, expanded polyurethane particles, and the like. Although there is no particular restriction on the particle size, those having an average particle size of 10 mm or less, usually in the range of 2 to 5 mm, are used. The amount of synthetic resin foam particles added must be 1 to 5 times the amount of cement used. If the blending amount is less than 1, the weight per unit volume of the mortar becomes heavy, making it impossible to obtain the desired lightweight mortar molded body. On the other hand, if the amount is more than 5 times, the synthetic resin foam particles in the mortar are likely to separate, and the compressive strength and other strengths of the resulting molded product will be reduced, which is not preferable. The lightweight mortar composition of the present invention further includes a dispersant (for example, a bituminous substance, a formaldehyde condensate of sodium naphthalene sulfonate as a main component) in order to uniformly disperse the synthetic resin foam in the mortar. It is necessary that a dispersant consisting of a surfactant and an anti-caking agent such as diatomaceous earth be contained. The water/cement (weight) ratio can be determined as appropriate depending on the amount of synthetic resin foam particles, quick setting agent, setting retarder, etc. used, but is generally 30 to 70.
%, usually 35-65%. The lightweight mortar composition used in the present invention includes:
It is necessary that the above aqueous kneaded product contains both an accelerating agent and a setting retarder. As the quick-setting agent, any commonly used one can be used without particular limitation. Examples of quick setting agents that can be used include sodium aluminate, sodium silicate, sodium carbonate, calcium aluminate, calcined alumite, etc., which can be used alone or in mixtures. . It is particularly preferable to use a quick-setting agent containing sodium aluminate as a main component. The quick-setting agent must be contained in the aqueous kneaded material in an amount of 2 to 10% by weight based on the cement. It is particularly preferable that the content of the quick-setting agent is in the range of 3 to 8% by weight. If the amount of the accelerating agent is less than 2% by weight, the curing accelerating effect will not be sufficiently exerted, and it will take a long time from the start of setting to demolding, which is not preferable. Furthermore, if the amount of the quick-setting agent is more than 10% by weight, the lightweight mortar poured into the mold will lose its fluidity before reaching the corners of the mold, making it impossible to obtain the desired molded product. This is not desirable as it may disappear. In such cases, it is possible to add an excess of setting retarder to secure the necessary time for the work, but adding too much setting retarder increases the product cost of the resulting molded product. In addition to letting
This is not preferable since it may adversely affect physical properties such as strength of the molded article. Any commonly used setting retarder can also be used without particular limitation. Examples of set retarders that can be used include oxycarboxylic acids such as citric acid and gluconic acid, salts thereof, and lignin sulfonates, which may be used alone or in combination. can. Particular preference is given to using citric acid as set retarder. It is necessary that the setting retarder is contained in the aqueous kneaded material in an amount of 0.1 to 3% by weight based on the cement. And the content of setting retarder is
A range of 0.3 to 2% by weight is particularly preferred. If the amount of setting retarder is less than 0.1% by weight,
The setting retardation effect is insufficient, and setting starts and reaches a hardened state in a short time after the addition of the accelerating agent, making it impossible to secure the time necessary for pouring the mortar mixture, or to prevent setting. If the effect of the retarder is insufficient, the effect of the quick-setting agent may not be uniformly manifested, and the lightweight mortar may partially set quickly. Furthermore, the lightweight mortar injected into the mold loses its fluidity before reaching the corners of the mold, making it impossible to obtain the desired molded body, which is undesirable. Furthermore, if the amount of the setting retarder added is 3% by weight or more, the effect of adding the quick setting agent becomes less apparent. However, although it is possible to shorten the setting start time by adding an excess of setting retardant to delay the setting start time due to the addition of an excessive setting retarder, adding such an excessive amount will result in no gain. This is not preferable because it not only increases the product cost of the molded product, but also adversely affects the physical properties such as strength of the molded product. The lightweight mortar used in the present invention is prepared by kneading cement, the synthetic resin foam particles, the dispersant, the setting retarder, and water to prepare a uniform aqueous mixture. Then, it is necessary to adjust the aqueous kneaded material by adding the above-mentioned quick setting agent. The preparation of the lightweight mortar can be carried out, for example, in a cement mixer. The effects of the present invention can be achieved by adding the quick-setting agent at the above-described timing. According to the present invention, by adding and blending both an accelerating agent and a setting retarder, which have essentially opposite effects, in a specific order and incorporating them into a lightweight mortar composition, the setting start time of the mortar composition is reduced. and the curing speed can be adjusted arbitrarily. That is, in a lightweight mortar composition containing both an accelerating agent and a setting retarder, the time from when the accelerating agent is added to when setting starts is controlled by the action of the setting retarder. After the setting starts, hardening is achieved within a short period of time due to the action of the quick setting agent. Therefore, by adjusting the amount of the setting retarder added, the time from the addition of the accelerating agent to the start of setting,
In other words, it is possible to adjust the time required for fluidity to be injected into the formwork to any desired time, and by adjusting the amount of the quick setting agent added, the curing speed, that is, the time after a predetermined period of time after setting starts can be adjusted. The curing state can be controlled. For the above reasons, in the method of manufacturing a molded object by injecting and curing a lightweight mortar composition into a mold, according to the present invention, both the quick-setting agent and the setting retarder are added in a certain amount within a certain range and in a specified amount. By mixing and using in this order, you can freely control the time (pot life) from the addition of the quick-setting agent to the injection of lightweight mortar until it hardens to the extent necessary for demolding. becomes possible. On the other hand, when preparing a lightweight mortar using the synthetic resin foam particles of the present invention as a lightweight filler, if a setting retarder and an accelerating agent are added at the same time, the pot life, compressive strength and The condition of the molded product tends to become unstable, making it difficult to produce a desired molded product with good reproducibility. The lightweight mortar composition of the present invention contains ingredients other than the above-mentioned cement, synthetic resin foam particles, dispersant, rapid setting agent, setting retarder, and water, as well as commonly used additives and aggregates. Other components may be added as appropriate to the extent that they do not contradict the purpose of the lightweight mortar composition of the present invention. In the present invention, "setting start time" refers to the time after the quick-setting agent is added to the aqueous kneaded material, or from the time when water is added to the cement composition mixed with the quick-setting agent and kneaded. The time from when the mortar composition starts to set until it starts to lose its fluidity, and the "demolition possible time" is the time when the strength of the lightweight mortar composition poured into the formwork increases until it starts to lose its fluidity. This is achieved to the extent that the molded product can maintain its own shape, that is, to the extent that it can resist some external force.On the other hand, the surface of the molded product immediately after demolding is smoothed with a plastering trowel, so-called "levelling". "Pot life" refers to the time when the product has fluidity to the extent that it can be molded, and "pot life" refers to the time from when the quick-setting agent is added to the time when it can be demolded. In addition, the term "curing speed" refers to the curing speed from the time when setting starts until the hardening state reaches a degree necessary for demolding. When adjusting the lightweight mortar composition, take into consideration, for example, the shape and volume of the molded object to be manufactured, or the time allotted for curing to a degree that allows demolding during the manufacturing process, etc. The amount of setting retardant and accelerating agent added is adjusted so that it has appropriate fluidity and does not start setting until the end of injection, and that setting starts immediately after injection and leads to hardening. . The amount to be added can be easily determined by preliminary tests. By adjusting the setting start time and curing speed in this way, the time when demolding is possible can be set to any desired time, but the time from the addition of the quick setting agent to the time when demolding is possible (pot life) is 2. Preferably, it is adjusted to any time in the range of ~60 minutes. The lightweight mortar composition whose demolding time has been adjusted by controlling the setting start time and hardening rate in this manner is poured into a mold, and is demolded after a predetermined period of time has elapsed. The molded product immediately after being demolded usually has a self-shape-retaining property, that is, it has a self-shape-retaining property to the extent that it can resist some external force, and is hardened to the extent that it can be leveled with a plastering trowel, for example. in a state.
Such a demolded molded body is usually partially repaired and then cured by a conventional method until it is completely cured. The lightweight mortar composition of the present invention can be used for producing molded bodies that need to be demolded from molds in a short period of time, since the time at which demolding is possible can be set arbitrarily.
For example, it can be used in a manufacturing method in which mortar is continuously poured into a mold to mass-produce molded objects such as panels. In addition, in the manufacturing process of molded bodies on a line, we adjust lightweight mortar compositions with different amounts of quick-setting agents and setting retarders to give molds of different shapes and capacities different pot times. By pouring a lightweight mortar composition having the same composition, it is possible to take out molded bodies of different shapes or capacities in substantially the same cured state at the end of the production line. Furthermore, in a production process where the production process is not organized into a production line, when a molded body is obtained by pouring a lightweight mortar composition into molds of different capacities or shapes, lightweight mortars with different amounts of quick-setting agent and setting retarder are used. It is also possible to adjust the composition, pour this lightweight mortar composition into the formwork at different times, and then demold them at the same time after a certain period of time so that the molded bodies with different curing times have almost the same hardening state. can. Next, Examples and Comparative Examples of the present invention will be shown. The lightweight mortar and the molded product of the mortar were tested in the following manner. (1) Unit volume weight JIS-A-1116 (2) Pot life After adding the quick-setting agent using the method (a) above, take a sample and perform a feel test with a plastering trowel to determine whether the quick-setting agent has been added. The time that can be leveled with a trowel was defined as the pot life. (3) Compressive strength JIS-A-1132 and JIS-A-
1108. However, when forming the specimen, no stick was used, but the surrounding formwork was struck 20 times with a wooden hammer to spread the lightweight mortar composition throughout the formwork. The compressive strength of the specimens was measured using specimens aged 3 hours and 7 days after addition of the quick-setting agent. In addition, as a dispersant for synthetic resin foam particles, 62% by weight of sodium naphthalene sulfonate/formaldehyde condensate, 6% by weight of sodium polycarboxylate,
A dispersant (manufactured by Azabe Kosan Co., Ltd., trade name: Lycoaid) consisting of 13% by weight of bituminous material and 19% by weight of diatomaceous earth was added to the cement at a rate of 0.85% by weight.
It was used by adding it in an amount of % by weight. Example 1 Expanded polystyrene particles (average particle size: 3 mm) were charged into a cement mixer in an amount twice the volume of the cement used. Next, a predetermined amount of Lycoaid and 0.3% by weight of citric acid based on the cement are dissolved and dispersed in water that is 40% by weight based on the cement to be used, and then put into the above cement mixer and mixed. Ta. Ordinary Portland cement was put into the above cement mixer and kneaded until the whole was homogeneous. After the whole is homogeneous, 3% by weight of sodium aluminate quick-setting agent (manufactured by Pozolis Bussan Co., Ltd., trade name: QP500L) is added to the cement, and the quick-setting agent is further dispersed throughout the cement. A lightweight mortar composition (kneaded product) was obtained by kneading the mixture. Table 1 shows the weight and pot life per unit volume of the lightweight mortar composition obtained, and the compressive strength at 3 hours and 7 days of age of the molded body produced using this lightweight mortar composition. In order to produce a specimen, the above-mentioned lightweight mortar composition was poured into a mold, removed from the mold after 2 hours, and observed. As a result, the cured state was good and no deformation was observed. Example 2 A lightweight mortar composition was obtained in the same manner as in Example 1, except that the amount of the quick-setting agent used was 4% by weight. Table 1 shows the weight per unit volume and pot life of the lightweight mortar composition obtained, and the compressive strength at 3 hours and 7 days of age of the molded body produced using this lightweight mortar composition. In addition, when the above-mentioned lightweight mortar composition was poured into a mold for the production of a test specimen, and the mold was removed after 2 hours and observed, the hardening state was good and no deformation of the shape was observed. Example 3 A lightweight mortar composition was obtained in the same manner as in Example 2, except that the amount of the setting retarder used was 0.9% by weight. Table 1 shows the weight and pot life per unit volume of the lightweight mortar composition obtained, and the compressive strength at 3 hours and 7 days of age of the molded body produced using this lightweight mortar composition. In addition, when the above-mentioned lightweight mortar composition was poured into a mold for the production of a test specimen, and the mold was removed after 2 hours and observed, the hardening state was good and no deformation of the shape was observed. Example 4 A lightweight mortar composition was obtained in the same manner as in Example 2, except that the amount of the setting retarder used was 1.5% by weight. Table 1 shows the weight and pot life per unit volume of the lightweight mortar composition obtained, and the compressive strength at 3 hours and 7 days of age of the molded body produced using this lightweight mortar composition. In addition, when the above-mentioned lightweight mortar composition was poured into a mold for the production of a test specimen, and the mold was removed after 2 hours and observed, the hardening state was good and no deformation of the shape was observed. Example 5 A lightweight mortar composition was obtained in the same manner as in Example 1, except that the amount of the setting retarder used was 1.5% by weight and the amount of the quick setting agent was 7% by weight. Table 1 shows the weight and pot life per unit volume of the lightweight mortar composition obtained, and the compressive strength at 3 hours and 7 days of age of the molded body produced using this lightweight mortar composition. In order to produce a specimen, the above-mentioned lightweight mortar composition was poured into a mold, removed from the mold after 2 hours, and observed. As a result, the cured state was good and no deformation was observed. Example 6 A lightweight mortar composition was obtained in the same manner as in Example 4, except that the amount of expanded polystyrene particles used was four times the volume of cement. Table 1 shows the weight and pot life per unit volume of the lightweight mortar composition obtained, and the compressive strength at 3 hours and 7 days of age of the molded body produced using this lightweight mortar composition. In addition, when the above-mentioned lightweight mortar composition was poured into a mold for the production of a test specimen, and the mold was removed after 2 hours and observed, the hardening state was good and no deformation of the shape was observed. Comparative Example 1 A lightweight mortar composition was obtained in the same manner as in Example 1, except that the amount of the quick-setting agent used was 1% by weight. Table 1 shows the weight per unit volume and pot life of the lightweight mortar composition obtained, as well as the compressive strength at 7 days of age of the molded article produced using this lightweight mortar composition. In order to produce a specimen, the above-mentioned lightweight mortar composition was poured into a mold and removed from the mold after 2 hours, but coagulation and hardening were incomplete and deformation was observed upon removal from the mold. In addition, the compressive strength of the specimen aged 3 hours could not be measured due to insufficient curing. Comparative Example 2 A lightweight mortar composition was obtained in the same manner as in Example 1, except that no setting retarder was used. Table 1 shows the weight per unit volume and pot life of the lightweight mortar composition obtained. In addition, since the lightweight mortar hardened rapidly, it was not possible to separate the mortar for molding the specimen. Therefore, it was not possible to measure the compressive strength. Comparative Example 3 A lightweight mortar composition was prepared in the same manner as in Example 1, except that a sodium aluminate-based quick-setting agent was dissolved in water together with citric acid (setting retardant), and the mixture was put into a cement mixer and mixed. I got something. The weight and pot life per unit volume of the obtained lightweight mortar composition, and the compressive strength of the molded body manufactured using this lightweight mortar composition were determined as follows.
Shown in the table. In addition, "deformation" was observed in the molded product obtained using the above composition, so the experiment was repeated a total of 5 times under the same conditions.
Partial "deformation" was observed in the molded bodies obtained in all experiments.

[Table] As is clear from the comparison of Example 1 and Comparative Example 1 above, the lightweight mortar composition of the present invention can reduce the setting start time by using a combination of an accelerating agent and a setting retarder within a certain range. The demoldable time can be controlled within a desired range. That is, in Comparative Example 1, the setting retardant was blended within a preferable range, but since the amount of the quick setting agent was small, the setting start time of the lightweight mortar composition was lengthened.
Therefore, it is unsuitable for use in the continuous production of molded bodies. Further, a composition lacking either an accelerating agent or a setting retarder cannot achieve the object of the present invention. For example, a composition lacking a setting retarder, as shown in Comparative Example 2, has too short a setting initiation time to be useful. In addition, if an accelerating agent and a setting retarder are added at the same time, the molded product is likely to show partial defects such as deformation, and the pot life and compressive strength of the molded product are likely to fluctuate and become unstable. It can be seen that it is difficult to obtain a molded body. In addition, although the lightweight mortar composition of the present invention contains an accelerating agent and a setting retarder, which have completely opposite effects, as is clear from the above examples, the compressive strength of the molded product is low after 3 hours. Even if the material is 7 days old, it is approximately 3Kg/cm ² or more, and even the lowest material (Example 6) is 21.6Kg/cm ² , and Example 5 is 36.8Kg/cm 2 cm ² strength was developed, and it is clear that the combined use of an accelerating agent and a setting retarder does not have any adverse effect on the original properties such as the strength of the molded article. Furthermore, the compressive strength of Examples 1 to 6 and Comparative Example 1
As is clear from the comparison of the compressive strength of the materials after 7 days of age, the curing speed was slow in Comparative Example 1, which contained a small amount of quick-setting agent, and the subsequent curing speed until complete curing was also slow. Compressive strength is not sufficiently developed. In addition, the lightweight mortar composition of the present invention has a fast curing speed due to the action of the quick-setting agent, and furthermore, it does not require long-term curing because it quickly reaches a completely hardened state and develops strength. It's also effective.

Claims (1)

[Scope of Claims] 1. Cement and a volume ratio of 1 to 1 to the cement.
5 times the amount of synthetic resin foam particles, a dispersant, a setting retardant in the range of 0.1 to 3% by weight based on cement,
A homogeneous aqueous kneaded material is prepared in advance by kneading with water, and then a quick-setting agent is added in the range of 2 to 10% by weight based on the cement, and this is added to the formwork. A method for producing a lightweight mortar molded article, which comprises injecting the molded article into a mold, setting it, hardening it, and removing it from the mold. 2. Production of a lightweight mortar molded body according to claim 1, wherein the amounts of the quick setting agent and the setting retarder are in the range of 3 to 8% by weight and 0.3 to 2% by weight, respectively, based on the cement. Method.