JPH0463036B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a lightweight cellular concrete cured with high temperature and high pressure steam using aluminum powder as a foaming agent, in which the difference in bulk specific gravity of the concrete part within the panel is small. This relates to large panels with small differences in performance within the panel.

(Prior art) Traditionally, a mortar slurry is created by adding a foaming agent using powdered silicic raw materials and calcareous raw materials such as cement and quicklime as the main raw materials, and this mortar is poured into a formwork, foamed, and hardened ( semi-plastic state)
There are panels of lightweight aerated concrete (hereinafter simply referred to as ALC) made of concrete that has been cut to predetermined dimensions and cured with high-temperature and high-pressure steam. This aluminum powder is used as a foaming agent.
ALC panels have the advantage of high compressive strength (compressive strength of 30 kg/cm ² or more according to JIS A 5416).

However, in order to increase productivity, this ALC panel uses multiple sets of reinforcing reinforcing bars arranged vertically within the formwork.
The main raw materials are powdered silicic acid raw materials and calcareous raw materials,
A mortar slurry mixed with a foaming agent such as aluminum powder is injected into this, and after it is cured, it is cut vertically using piano wire and cured in high-temperature, high-pressure steam to produce ALC panels.Many panels are made in the same formwork. It was obtained using a multiple molding method that simultaneously creates the

However, in this rigid multiple molding method where many panels are produced simultaneously using one formwork, the mortar slurry has a height, so the foaming height becomes large, and the foaming occurs somewhat between the top and bottom of the mortar slurry. Due to unavoidable unevenness, the panel width is 600mm.
They were only able to produce a small number of panels. Even for ALC panels with a panel width of about 600 mm, the difference in bulk specific gravity within the panel was more than ±2%, or more than 4%, relative to the average bulk specific gravity of the concrete part of the panel, but the compressive strength of the panel was is 30
Since it was sufficiently high at Kg/cm ² or more and the panel width was about 600 mm, the practical performance as a panel in bending performance tests etc. was sufficient, and the panel was sufficiently durable for practical use.

Although there is no problem in terms of practical strength with a width of about 600 mm, large panels with a width of 1500 mm or more, for example 180 mm, were created using the rigid multiple molding method described above, but the internal strength of the panel This resulted in large variations in performance, and performance such as bending performance tests was insufficient, making it impossible to obtain large panels that could be put to practical use.

In addition, when trying to obtain large panels using the above method, mortar slurry is injected from the top of the formwork, which causes air bubbles to accumulate and air to be trapped due to the impact of falling, resulting in large air bubbles, voids, and cavities. Moreover, a void larger than the diameter of the reinforcing bar is generated around the top of the reinforcing reinforcing bar, and the resulting large panel has a portion where the strength is further reduced, and the panel is not strong enough to withstand practical use.

Therefore, a foaming agent that has already foamed is added to the normal mortar raw materials of silicic acid raw materials and calcareous raw materials to homogenize the air bubbles, and the integral molding method (so-called "flat molding method") used in precast concrete is used.
A method of obtaining large ALC panels is also being attempted.

However, this method involves the production of one piece of formwork, and with ordinary mortar slurry, it requires a long period of curing to develop the strength necessary for demolding, which has the major drawback of slowing down the formwork turnover rate. This method has extremely low productivity compared to the multiple molding method described above. Therefore, in order to compensate for this drawback, in addition to ordinary Portland cement as a silicate raw material and a calcareous raw material, alumina cement is actually used as a rapid setting raw material to improve the early strength of mortar.

As the name suggests, this alumina cement has alumina as its main component and is composed of a calcium aluminate phase such as CA, CA ₂ , etc. This calcium aluminate phase hydrates when injected at a temperature around room temperature. Generates calcium aluminate hydrates such as CAH ₁₀ , C ₂ AH ₈ , etc. to develop the initial strength of mortar, and when used in combination with a foaming agent, the curing time is shortened, and large ALC panels can be produced even with the flat molding method. It is something that can be done. However, this alumina cement was used as a quick setting agent.
ALC panels are made from calcium silicate hydrate from the tobermorite group, which exhibits the basic characteristics of ALC and improves its strength when subjected to autoclave treatment, or high-temperature and high-pressure steam curing, which is an essential requirement for ALC production. Hydrogarnet, which is a constituent component, is inevitably produced in such a large amount that it can be seen by powder X-ray diffraction. This hydrogarnet is a hydrate having a composition such as C ₃ AH ₆ and C ₃ ASH ₄ , but generally these hydrates have extremely low strength development properties and are hydrates of the tobermorite group. Compared to 11Å tobermorite, its strength is about 1/10, and it can be used in combination with alumina cement.
ALC has the disadvantage that its strength is significantly lower than that of ALC without alumina cement.
Moreover, alumina cement is expensive, so it is difficult to obtain
ALC panels were also becoming more expensive.

The present inventor aimed to develop a large panel with practical panel strength (strength that satisfies the bending performance test, etc., which is a problem in the practical performance of the panel).
At first, the so-called flat casting method was used, in which one panel was produced using one formwork in which reinforcing bars for one panel were horizontally fixed in the formwork using the same mortar raw material used in the conventional multiple molding method. Although an attempt was made to produce a panel using this method, it was not possible to obtain a panel with a panel strength that could be put to practical use.

Further, no matter how much improvement was made to the above-mentioned method using a foaming agent, it was impossible to make the panel strength equal to or higher than that of commercially available ALC panels that do not use alumina cement.

OBJECTS OF THE INVENTION The object of the present invention is to provide a large lightweight cellular concrete panel with practical panel strength without the drawbacks of the prior art.

(Means for Solving the Problems) The present invention is a lightweight aerated concrete panel cured with high temperature and high pressure steam using aluminum powder as a foaming agent, which has a panel width of 1500 mm or more, a panel length of 2000 mm or more, and a panel thickness of 75 mm or more. It is a large lightweight aerated concrete panel, and the difference in absolute dryness and specific gravity between any two concrete parts within the panel is always within 2%, and the hydrogarnet is substantially confirmed by powder X-ray diffraction. This invention relates to large lightweight aerated concrete panels that are characterized by the fact that they are not

That is, the inventor of the present invention found that in order to have practical panel strength in a large lightweight aerated concrete panel with a panel width of 1,500 mm or more, a panel length of 2,000 mm or more, and a panel thickness of 75 mm or more, aluminum powder was used as a foaming agent. They discovered for the first time that when used, the difference in absolute dry bulk specific gravity between any two concrete parts within a panel must always be within 2%.

The large ALC panel of the present invention has a panel width of
1500mm or more, preferably 2600mm or less, panel length
2000 mm or more, preferably 2400 mm or more, particularly preferably 4000 to 8000 mm, and a panel thickness of 75 mm or more, preferably 120 mm or more and 250 mm or less.

In the present invention, the difference in absolute dry bulk specific gravity between any two concrete parts within the panel is always 2%.
If the compressive strength of any part is equal to or greater than the compressive strength of the concrete part of a commercially available ALC panel with a width of 600 mm (40 Kg/cm ² or more, for example 47 to 52 Kg/cm ² in any part) ) and has a practical panel strength, making it the first large panel as described above to be put to practical use.

In order to manufacture the large-sized ALC panel of the present invention with the above configuration, aluminum powder is used as a foaming agent, and the moisture ratio of the mortar forming raw material is reduced, for example, the following representative composition (in this case, mortar C /S ratio is desirably 0.8 or less. By producing panels using the so-called flat casting method, it is possible for the first time to ensure that the difference in absolute dryness and specific gravity between any two concrete parts within a large panel is always within 2%, making it a practical panel. The result is a large, strong ALC panel.

Typical mortar composition: Cement: 40 parts by weight (for example, ordinary Portland cement) Silica: 50 parts by weight Quicklime: 10 parts by weight Water: 60 parts by weight measured by the method.

That is, based on JIS-A-5416, a concrete member of 10 cm square, which does not include reinforcing steel members, etc., is cut out from the target large panel, and its absolute dry bulk specific gravity is measured. In this way, if we measure the bone dry specific gravity at multiple locations on a large panel, and let the bone dry specific gravity at any two locations within the panel be ρ ₁ and ρ ₂ (ρ ₁ ≦ρ ₂ ), then (ρ ₁ −ρ _{2 )}
)÷
Find ρ ₁ . In the present invention, it is essential that this value is always 0.02 or less in order to obtain a panel with practical strength as described above. Even when dryness specific gravity is measured, it is essential that the difference between the highest and lowest values is 2% or less with respect to the lowest value, as described above.

It is preferable that the ALC panel of the present invention does not contain alumina cement, but even if a small amount of alumina cement is added, the presence of hydrogarnet will be determined by powder X-ray diffraction after the panel is made into a product. If the amount of alumina cement added is such that it cannot be confirmed, there will be no substantial effect on the quality of the ALC panel, but if the presence of hydrogarnet is detected by powder X-ray diffraction, the quality of the ALC panel will deteriorate The inventor has confirmed that this product cannot be called a product of the present invention.

Furthermore, since the ALC panel of the present invention is also characterized by its manufacturing method, it is possible to accurately mount it at a desired position by fixing the mounting fittings to reinforcing reinforcing bars. Therefore, even large panels can be easily constructed, and construction costs can be reduced.

In general, the average absolute dry bulk specific gravity of the concrete part of the ALC panel is preferably 0.40 to 1.00, and particularly preferably 0.45 to 0.60. It is preferable to have a light weight of 0.60 or less, especially when making a large panel.

(Examples) The present invention will be described in detail below based on Examples.
As shown in Figures 1 and 2, for example, the width is 1800mm~
2600mm, length 4000mm~8000mm, side height 100mm~250mm
Reinforcement reinforcing bars 3 that have been knitted in advance are installed in the formwork 1 (for example, the side plates 2 are moved and the product length is changed to a desired length). For this drawing,
Embedded metal fittings 4 are fixed to reinforcing reinforcing bars 3 at four locations. By using this embedded metal fitting 4 to support the reinforcing bar fixing jig 5 perpendicularly to the bottom surface of the form, the reinforcing reinforcing bar 3 is fixed at an accurate position. In this drawing, spacers 6 are fixed at desired positions to form an open panel. No reinforcing steel bars are present in the space occupied by the spacer 6. These spacers are available in several sizes, ranging from 300mm to 2100mm in width, depending on the size of the opening, and the materials used include iron, stainless steel, plastic, rubber, and aluminum. After the desired concrete hardness is achieved, the spacer is removed to form an opening in the panel. A mortar slurry (containing about 0.07 parts by weight of aluminum powder) with a lower water content than the conventional mortar described above is poured into the mold thus prepared. This slurry is precured for about one hour at 60°C, for example, for a short time of about one-half to one-third compared to the conventional multiple molding method, and then demolded. Since the time required for demolding is short, there is no significant difference in productivity compared to the conventional multiple molding method.

Since the mortar may bulge on the upper surface of the panel, the upper surface of the panel is cut smoothly by an appropriate means such as piano wire after preliminary curing.

If necessary, the lower surface of the ALC panel 7 (the surface in contact with the bottom surface of the formwork) may be polished to expose the cut surface of the bubbles 8 on the panel surface as shown in FIG. When the cut surface of the bubble is exposed on the panel surface in this way, the difference in bone dry bulk specific gravity within the panel is within 2%, as seen in the measured value of bone dry bulk specific gravity described later. The cut air bubbles that appear are evenly dispersed, so when something is applied to the panel surface, even if the thickness of the applied material is thin, it will be evenly distributed and have sufficient adhesion. This means that the panel can be attached with a 100% carbon fiber, and this panel can demonstrate excellent performance in this aspect as well.

The panel thus precured and demolded is then cured in high temperature and high pressure steam. For example, general high-temperature, high-pressure steam curing conditions using saturated steam with a gauge pressure of 8 to 12 Kg/cm ² are applied.

The large ALC panel obtained in this way is
We continuously cut out 10 cm square samples and performed bone dry bulk specific gravity measurements and powder X-ray analysis.The average value of bone dry bulk specific gravity was 0.5, and the difference between the highest and lowest bone dry bulk specific gravity values was Within 2% of the minimum value (in measurement examples of three large panels of the present invention with different specific manufacturing conditions, 1.6%, 1.2%, and 1.4%, all within 2%)
%), and no hydrogarnet formation was observed even by powder X-ray analysis. Also,
The compressive strength of the concrete part is 50Kg/ ^cm2 ,
Furthermore, the strength of the panel, which is a problem in practical applications such as bending performance tests, has been improved, and the panel is large enough to be put to practical use.

(Effects of the Invention) The large-sized ALC panel of the present invention has the above-mentioned structure, so it does not require the use of large amounts of expensive alumina cement, and has the characteristic of having a strong average compressive strength unique to ALC panels using aluminum powder. The compressive strength of all parts of the panel is 40 Kg/cm ² or more without loss of strength, and the panel has an excellent effect of having practical panel strength even though it is a large panel.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a formwork used in an embodiment of the present invention, and FIG. 2 is a sectional view thereof. FIG. 3 is an enlarged cross-sectional view of the ALC panel of the present invention, showing the state of the cut surface of the ALC panel. 1...Formwork, 2...Side plate, 3...Reinforcing reinforcing bars, 4...Embedded metal fittings, 5...Jig for fixing reinforcing bars, 6...Spacer, 7
...ALC panel, 8...Bubble cross section.

Claims (1)

[Claims] 1 Lightweight aerated concrete panels cured with high-temperature, high-pressure steam using aluminum powder as a foaming agent, with a panel width of 1,500 mm or more and a panel length of 2,000 mm.
It is a large lightweight aerated concrete panel with a thickness of 75 mm or more and a panel thickness of 75 mm or more, and the difference in bone dry specific gravity between any two concrete parts within the panel is always 2
% or less, and substantially no hydrogarnet is observed by powder X-ray diffraction.