JPS6243952B2 - - Google Patents

Description

[Detailed description of the invention]

Conventionally, in the manufacturing method of lightweight cellular concrete, coarse cavities (3 to (approximately 10 mm), resulting in a significant appearance defect when the product was used as wall material. In addition, in most cases, the product surface is painted, but in this case, it takes a lot of man-hours to repair the rough cavities, and even if the repair is done, the appearance is not good. The current situation is that it is increasing. The cause of this coarse cavity is the entrainment of air due to the occurrence of turbulent flow at locations where air exists in the path during injection shown in FIG. As a countermeasure to this problem, attempts have been made to make the flow during injection laminar or to create a structure that facilitates defoaming, but these have not been very effective. It is also known that air bubbles trapped in the mortar after injection are forcibly removed using a rod-shaped vibrator.
With this method, it was difficult to uniformly degas the mortar throughout the formwork. Further, if an attempt is made to increase the uniformity, a large number of vibrators will be required, making it impractical to accommodate the equipment. In particular, as shown in Figure 2 A, D, and E, the vicinity of the rod-shaped vibrator in mortar 2, Figure 2 D-4.
The degassing effect is affected by the fact that heavy vibration cannot be avoided due to strong vibration (at this time, some of the mortar has already started foaming, and the destruction of these bubbles is the main cause) and the distance from the vibrator. It is about change. The present invention overcomes the above drawbacks and provides a thixotropic mortar slurry with relatively low viscosity (300 to 9000 centipoise as measured by a B-type viscometer) in which fine powder is dispersed, and which also contains a blowing agent. It has been found that forced defoaming can be carried out uniformly and effectively by vibrating the bottom plate of the form during partial foaming. Conventionally, heavy mortar, such as concrete mortar containing aggregates such as gravel,
As typified by the slump value, even if the mortar immediately after mixing is placed on a horizontal table, it will not flow until it becomes flat, but will be in a heaped state. When mortar is filled into mold crushers, there are large voids and gaps 10 as shown in Figure 1 A. To eliminate these, vibrations at a relatively low frequency are applied to remove large and small particles in the concrete mortar composition. As each aggregate moves, the mortar is also supposed to move to evenly fill the space. In other words, in this method, the fluidity of the mortar is extremely poor and it is difficult to uniformly inject the mortar into the molds 1 and 7, which is why vibrations are applied. For this reason, even the table vibrating type 9 requires a greater amount of vibration than the present invention.
In addition, the main purpose of these heavy mortars is to uniformly fill the mortar or to improve its compactness, and especially to eliminate voids on the mold release surface. On the other hand, in the case of mortar containing a blowing agent such as the one of the present invention, it blends well with the formwork,
The main purpose is not to improve the mold release surface or make the mortar composition dense, but only to defoam the air bubbles in the mortar that are caught during pouring. For this reason, it is preferable to vibrate at a relatively high frequency.
For lightweight aerated concrete, the parts indicated by the dotted lines in Figure 2 F, E, and C are examples of cut points.
Because horizontal and various types of molds are cut with 0.8 to 10 steel wire, large bubbles of trapped air appear on the cut product surface, and as a countermeasure, only the air trapped in the mortar can be defoamed. Becomes the object of the invention.
Furthermore, when pouring lightweight aerated concrete (containing a foaming agent), vibration of the bottom plate of the formwork is thought to be extremely difficult due to the following reasons, and therefore this practice has not been carried out. 1. Mortar already contains a foaming agent, and degassing this is difficult in part because it promotes foaming, but also causes foam collapse, resulting in uneven foaming, and this method should not be used. was. 2. Lightweight aerated concrete has an absolute dry specific gravity.
Since most of the mortar is about 0.5, the strength of the block is weak when the mortar is semi-hardened, and for this reason, when the block is transferred in a semi-hardened state, if the level of the bottom plate of the block is rotated even slightly, the block may break or crack. For this reason, the level accuracy of the formwork bottom plate of lightweight aerated concrete is required to be severe, unlike concrete products such as ready-mixed concrete, and therefore, it is considered extremely difficult to use a method that vibrates the formwork bottom plate. Therefore, it had not been implemented. 3. The viscosity of mortar slurry is much lower than that of concrete products such as ready-mixed concrete, and mortar leakage from formwork is extremely disadvantageous. However, contrary to the above common sense, the present inventor first adopted a method of vibrating the bottom plate of the formwork, which had previously been unthinkable for lightweight aerated concrete, from the viewpoint of uniformly and completely removing air entrained in the mortar, which is the main purpose. Then, the present invention was completed by finding a condition in which the vibration is carried out immediately during and after the injection, while the foaming agent is partially foaming in a small amount. Next, details of the present invention will be explained in order. The mortar slurry in the present invention is a mixture of silica, quicklime, cement, gypsum, etc. that has been finely ground to such an extent that 50% or more passes through a sieve with an 88μ sieve opening, in a predetermined ratio as shown in the examples. It is made into a slurry by adding 50 to 90% water to the solid content of 100%. In addition to these, the composition contains modifiers such as fluidity improvers and hardening accelerators, or finely pulverized fillers, if necessary. In addition to the above slurry, a solid foaming agent that reacts with an alkali such as aluminum powder to generate hydrogen gas is added to the slurry.
Add 0.01 to 0.10 parts per 100. As shown in Fig. 5, it is more preferable for the injection method to be devised to make the mortar flow laminar, but by implementing the present invention, the injection method is not particularly limited in relation to defoaming of trapped air bubbles. You don't have to. Next, the relationship between formwork is as follows. The formwork dimensions are not particularly limited and can be used as long as they are suitable for lightweight aerated concrete products, but a formwork with a lower mortar injection height of 80 mm to 200 mm can be applied to a wider range and prevents trapped air bubbles. A favorable result is obtained for defoaming. Next, regarding vibrating the formwork bottom plate 1,
The key points are as follows. It is advantageous to vibrate only the bottom plate as uniformly as possible to give uniform vibration to the mortar, that is, to eliminate bubbles, and since the bottom plate 1 is usually the widest surface in contact with the mortar 2, this is Vibration is very efficient due to the effect of vibration. Another important point is to apply vibrations only to the bottom plate portion 1 of the formwork as much as possible in order to avoid applying unnecessary vibrations to the formwork. In the present invention, as a method of applying vibration to the mortar slurry 2, in the case of a thick bottom plate made of steel with high rigidity, it is preferable to attach the vibrator 4 directly to or in close contact with the bottom plate 1 as shown in Fig. 3; In such a case, it is preferable to attach the vibrator 4 to or closely contact the functional part of the bottom plate, which is a one-piece structure with a frame for maintaining the flatness accuracy of the bottom plate of the formwork. In this case, a method in which the bottom plate itself or a portion close to the bottom plate is vibrated is more preferable. Furthermore, as shown in FIG. 4, a vibrator may be brought into close contact with or attached to the top surface of the mold, and vibrations may be transmitted through the bottom plate surface of the mold.
As shown in Fig. 2, when the formwork bottom plate 1 is made larger than the product mortar block, a vibrator can be attached or closely attached to the part 4 in Fig. 2 (ro) to effectively vibrate through the bottom plate. can be communicated. As the vibration source, the most preferable method is to install or set a vibration motor with an eccentric on both sides and bring this vibration into close contact with the bottom plate of the formwork using a magnet.The frequency may also be adjusted using a frequency converter. can. In this case, the capacity and number of motors may be selected and arranged so that the following vibration conditions are satisfied on the bottom plate of the formwork of each section when mortar is actually filled in the formwork. The vibration conditions that must be met are an average acceleration of 0.5G or more, a swing width of 0.03mm or more, and a vibration frequency of 4000 times/min or more. Among these, particularly preferable vibration conditions are as follows, which are the same as above. Average acceleration 1G~10G
Width 0.03~1mm, frequency 5000~12000VPM. In addition, it is preferable to suppress the vibration width and increase the vibration frequency from the viewpoint of degassing effect and reducing the load on the formwork. Note that if the maximum vibration load is applied, and there is a risk of damage due to large mortar scattering or large resonance of the entire formwork, the capacity of the vibrator may be slightly lowered. Next, there are the following types of vibration sources that manually apply vibrations to the upper surface of the bottom plate of the formwork from the top of the formwork each time a vibration operation is performed. It is usually called the wall-hitting type,
It is a type of lightweight vibrator. It has an output of about 220W, a vibration frequency of 9000 to 12000 times/min, and a swing width of about 0.6mm. By placing it in close contact with the bottom plate, vibrations are transmitted to the mortar via the formwork bottom plate. Further, the vibration applied to the bottom plate of the formwork may be horizontal vibration in addition to vertical vibration of the bottom plate. As a main method of obtaining horizontal vibration, there is also a method of closely pressing the vibrator 4 against the side surface of the bottom plate portion 1 of the formwork. The next time to apply vibration is as follows. The vibration may be started at any time as long as mortar is present on the bottom plate 1 of the formwork. The timing at which the vibration ends varies depending on the height of the mortar from the bottom plate 1 of the formwork to the top of the block, the viscosity of the mortar, etc., but as a rough guide from the appearance, gas is released from the top surface of the mortar 2 under vibration load due to defoaming. The bubbles will pop out like a crater on the moon, and when the bubbles have almost completely disappeared, it will be the end of the vibration. Next, the relationship between the amount of foaming and the vibration timing in the present invention is as follows. First of all, the final foaming amount in the present invention is defined as "the height of the mortar slurry 2 immediately after pouring as shown in Figure 2A is subtracted from the height of the mortar that has completed foaming and hardened as shown in Figure 2F". For those with an absolute dry specific gravity of 0.50, the ratio of the injection amount to the final foaming amount is about 100:65 to 90. Further, although some of the foaming agent foams after mixing the foaming agent and before the injection is completed, in the present invention, the amount of foaming after this injection indicates the timing to apply vibration. After mixing the foaming agent until the injection is complete, it usually takes 1
If you allow free foaming during this time, the final foaming amount per minute will vary depending on the foaming agent.
Foams 0.2% to 5%. In actual injection, free foaming does not occur, but due to foam collapse during injection, the foam is injected with a slight amount of foaming. In the present invention, after injection is completed, vibration is preferably applied within 30% of the final foaming volume (as confirmed in advance by the foaming volume when foaming is performed without vibration after injection), preferably within 5%. be. Ideally, the foaming agent in the mortar should not foam until the vibration is complete after it is injected into the formwork.
Part 1 foams in reality. In the form bottom plate vibration method as in the present invention, even if the partially foamed mortar collapses during vibration, by increasing the amount of foaming agent in advance, it is possible to obtain the specified absolute dry specific gravity. , the mortar density can be made uniform within the formwork. When applying vibration after pouring all of the mortar, the mortar moisture should be 50 parts by weight per 100 parts by weight of solids.
~80 parts by weight and a period of 1 to 5 minutes of vibration under the vibration conditions described above is sufficient. Further, since the apparent viscosity of the mortar increases due to the foaming of the foaming agent, it is preferable that the time for defoaming the entrained air is when the foaming of the foaming agent is small and the mortar viscosity is low.
Table 1 shows examples of viscosity changes due to mortar foaming.

[Table] Mortar viscosity is measured using B-type rotational viscometer rotor #3.
The value is at 30 rpm and 40℃. Next, the composition and viscosity of mortar and the effect of defoaming due to vibration are as follows. The ease with which air trapped in mortar can be degassed using the form bottom plate vibration method of the present invention is related to mortar viscosity, and the relationship is shown in FIG. The horizontal axis is the viscosity of the mortar slurry immediately after mixing the foaming agent at 40° C. using B-type rotational viscometer rotor #3 and a rotor rotation speed of 30 rpm, and the unit is centipoise. The vertical axis shows the air bubble inclusion coefficient;
As shown by the dotted lines in Figures F and C, mortar is injected into the formwork, pre-cured, and after removing the side plate, the top surface of the mortar 2 is cut with a 0.80 piano wire to make it a smooth surface, as follows: This is the calculated coefficient. Air bubble inclusion coefficient is the air bubble diameter of 3 to 5 on the printing plate.
Categorize into less than mm, 5 to less than 7 mm, 7 to less than 10 mm, and more than 10 mm, count the plate surface per ¹ m2, and
It is the sum of the products multiplied by 16, 36, 64, and 100, and indicates the degree of air bubble inclusion, and the larger the amount of air bubble inclusion, the higher the value. The black circles in Figure 6 show the relationship between mortar viscosity and air entrainment coefficient without vibration treatment.
When the mortar viscosity is 1,000 centipoise or more, the coefficient is between 300 and 3,000, and coarse bubbles become noticeable, which is not practical. On the other hand, the white circles are those that have been subjected to vibration, and can be greatly improved to a state where the air bubble inclusion coefficient is reduced by 1/10 or zero. The mortar slurry described in FIG. 6 is based on the mortar composition described in Example 1, and only the water content is changed in the mortar composition. The relationship between moisture and viscosity is as shown in FIG. In the mortar of the present invention, the mortar slurry has a structural viscosity called thixotropy, and it is difficult to simply express the mortar viscosity, so it is necessary to clarify the measurement conditions. The mortar slurry of the present invention having thixotropy is shown in Fig. 7.
It will show different values depending on the rotation speed of the viscometer: 12 rpm, 30 rpm, 60 rpm. That is, the higher the rotational speed, the more the structural viscosity is destroyed and the viscosity becomes lower. The mortar viscosity in the present invention is 300~
9000 centipoise refers to the low to medium viscosity range as follows. With B-type viscometer rotor No. 3,
The state is shown at 30 rpm, and in the range of 3000 to 9000 centipoise, the measured value is shown at 12 rpm with rotor No. 3. Moreover, the measurement temperature was 40°C. Furthermore, the mortar viscosity range of 300 to 9000 centipoise as used in the present invention refers to a water ratio of 90 centipoise to 100 parts by weight of solid content.
~45 parts by weight. The mortar viscosity in FIG. 6 correlates with the mortar viscosity shown by the 30 rpm line in FIG. 7, which shows the relationship between mortar moisture. The lower the viscosity of the mortar, the faster the rate of rise of trapped air bubbles and the easier defoaming. The effect of destroying air bubbles, small air bubbles coalescing with each other, and accelerating the rising and defoaming speed of air bubbles can significantly reduce the number of air bubbles entrained in mortar. When the mortar viscosity is up to about 2000 centipoise as shown in FIG. 6, the air bubble inclusion coefficient can be set to zero or less than 1 part 100 as shown in FIG. 6 under the following vibration conditions. In other words, with mortar in the formwork, the average acceleration of the formwork bottom plate is 1G to 5G vibration frequency.
5000-8000VPM, vibration time 1-2 minutes. When the mortar viscosity is 2,000 to 5,000 centipoise as shown in FIG. 6, the air bubble inclusion coefficient can be less than 100 as shown in FIG. 6 under the following vibration conditions. In other words, with mortar in the formwork, the average acceleration of the formwork bottom plate is 3G to 10G, and the vibration frequency is 6000VPM to
12000VPM, vibration time 1-2 minutes. If no vibration is applied, the bubbles will vary greatly depending on the method of injection (particularly as the mortar viscosity increases). On the other hand, by applying vibration, a uniform degassing surface can be obtained, and the variation in the air bubble mixing coefficient shown in FIG. 6 is also greatly reduced. Next, an explanation will be given based on an example. Example 1 30 parts by weight of Portland cement, 8 parts by weight of quicklime fine powder (approximately 88μ), 44 parts by weight of silica fine powder with an 88μ pass of 95% or more, and solid recovered kudzu mortar having the same composition as above. 18 parts by weight and water
70 parts by weight were mixed in the mixer 14, and then 0.07 parts by weight of fine aluminum powder as a foaming agent was added and stirred for 30 seconds. The mortar viscosity at this time was 1500 centipoise using a B-type rotational viscometer using roller #3 at a rotation speed of 0 rpm and a slurry liquid temperature of 40°C. or,
The foaming characteristics of the Al used at this time were 10% at 3 minutes after injection, 20% at 5 minutes, and 20% at 5 minutes, respectively, relative to the final foaming amount.
It foams at a rate of 50% in 10 minutes, and has the characteristic of foaming at a rate of 2% per minute after mixing Al and before injection. Immediately after mixing Al, as shown in Figure 3 and Figure 5,
It was poured to a depth of 10 cm into formworks 1 and 7 with inner dimensions of . It took 1 minute from the start of the injection to the completion. Thereafter, the formwork bottom plate 1 was vibrated for 1 minute as shown in FIG. A 40Kg reinforcing steel cage with anti-corrosion treatment prior to injection,
One sheet was set so that it would not shift even if it was subjected to vibration. Next, the vibration conditions are as follows. Frequency
The power was 6500VPM and the average acceleration was 2G. However, this acceleration is an actual value measured on the bottom plate of the formwork containing mortar. After the vibratory degassing was completed, the mortar showed numerous traces of air bubbles, which were traces of degassing, indicating that degassing had occurred. After hardening this mortar block to a mortar hardness that allows the side plates to be removed, cut it with piano wire 0.80 to a smooth surface at a position 125 mm from the formwork bottom plate 1, and calculate the air entrainment coefficient of that surface. I measured it and it was zero.
There were no bubbles larger than 3 mm, and the appearance was very good. Also, at this time, the block height before cutting is 185mm.
It was hot. Furthermore, the variation in specific gravity within the same formwork was measured at 12 equally spaced locations and was found to be ±1%, which was extremely good and no heavy areas were observed. Moreover, the absolute dry specific gravity of the unreinforced portion of the obtained plate was 0.50. Example 2 The solid content was the same as in Example 1, and the solid content was
A mixture of 100 parts by weight and 50 parts by weight of water was mixed in a mixer 14, and then 0.07 parts by weight of fine aluminum powder as a foaming agent was added and stirred for 30 seconds. Mortar viscosity at this time Type B rotational viscometer #3 rotor, 30 rpm
The liquid temperature was 40°C and 2800 centipoise. Immediately after that, as shown in Figure 3,
The mixture was poured into molds 1 and 7 having internal dimensions of 1.8 m x 0.2 m in height to a depth of 10 cm. From the start of injection to completion 2
It was hot in minutes. The foaming properties of the Al used were 6% at 3 minutes and 6% at 5 minutes after injection, respectively, based on the final foaming amount.
15%, foams 37% in 10 minutes, and Al
It has the property of foaming at a rate of 1% per minute after mixing and before injection. Thereafter, the formwork bottom plate 1 was vibrated for 2 minutes as shown in FIG. The vibration conditions at this time are as follows. The vibration frequency was 7200VPM and the average acceleration was 5G. However, this acceleration is an actual value measured on the bottom plate 1 of the formwork containing the mortar 2. After vibration defoaming, we measured the air entrainment coefficient on that surface after horizontal cutting in the same way as in Example 1, and found that it was slightly
It was 96. The plate obtained by molding in the same manner as above without applying vibration had an air inclusion coefficient of 2190. Moreover, the absolute dry specific gravity of the unreinforced portion of the obtained plate was 0.55. As described above, according to the present invention, most of the air bubbles trapped inside the lightweight cellular concrete mortar can be defoamed, and a plate with a good appearance without uneven air bubbles on the product surface can be obtained.

[Brief explanation of the drawing]

Figures 1A and 1B are cross-sectional views of conventional vibration compaction for heavy mortar such as concrete mortar. Figure 2 A, B, C,
D, E and F are cross-sectional views of the situation from the completion of injection of lightweight aerated concrete slurry to the completion of foaming in a method using a foaming agent. E shows the case where the mortar part was spot-treated with a rod-shaped vibrator, and A to B and C show the cases where the method of vibrating the bottom plate of the form according to the present invention was carried out. Each shows the state of defoaming and small bubble formation. FIG. 3 is a cross-sectional view of the situation in which vibration is applied from the bottom of the bottom plate of the formwork to defoam the mortar. FIG. 4 is a plan view (A) and a cross-sectional view (B) of a situation in which vibration is applied from the upper part of the bottom plate of the formwork to defoam the mortar. FIG. 5 is a perspective view showing a situation in which mortar is injected into the formwork and defoaming treatment is performed. 6th
The figure is a graph showing the relationship between the mortar viscosity and the air bubble inclusion coefficient showing the effect of defoaming according to the present invention. The black circles are those without vibration defoaming treatment, and the white circles are those subjected to vibration defoaming treatment. FIG. 7 is a correlation diagram between mortar moisture and mortar viscosity. Reference numbers in the drawings: 1 is the formwork bottom plate, 2 is the mortar slurry, 3 is the reinforcing steel, 4 is the vibrator, 5 is the shock absorbing material part that absorbs vibrations, 6 is the formwork holding part, 7 is the formwork side plate, 8 10 is a formwork truck, 9 is a vibration table, 10 is a gap, 11 is an entrained air bubble, 12 is a small bubble caused by a foaming agent, 13 is an injection nozzle, 14 is a mortar mixer, and 15 is an injection port.

Claims (1)

[Claims] 1. When a lightweight cellular concrete mortar slurry made by adding water to slurry using finely pulverized powder raw materials and further adding a foaming agent is injected into a formwork, the mortar slurry in the injected formwork A lightweight aerated concrete using a foaming agent that vibrates the bottom plate of the formwork with a viscosity of 300 to 9000 centipoise, which vibrates the mortar slurry and defoames the air trapped in the mortar. Mortar injection processing method.