JPS58213670A - Manufacture of lightweight foamed concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A lightweight, rapid hardening material using an air-containing cellular cement slurry comprising the present invention's TRX hydraulic cement material, calcium aluminate minerals, natural zeolite, water, and an air-containing cellular foaming agent. Concerning the manufacturing method of aerated concrete.

Conventionally, when forming an aqueous slurry of hydraulic cement using an air-containing foaming agent to form a foam, alumina was added to the aqueous slurry in order to increase the turnover rate of the formwork and increase productivity. Attempts have been made to impart rapid hardening by adding appropriate amounts of calcium aluminate minerals such as cement. In a concrete body formed using such an aqueous slurry, air-containing bubbles often exist independently and partially connected. In this case, the bubbles may open to the outer surface of the concrete body. The molded product obtained as described above has excellent heat insulation properties, light walling properties, and fire resistance, and is about to be widely put into practical use.

However, although the above-mentioned addition of calcium aluminate minerals to impart rapid hardening contributes to the promotion of initial strength development, long-term strength is In addition to lowering the strength after certain autoclave curing treatments, water absorption tends to increase.

Furthermore, when alumina cement is used as the calcium aluminate mineral, the cement is energy-intensive and thus often increases the product cost.

It is therefore an object of the present invention to provide a method for producing lightweight cellular concrete using an aqueous slurry consisting of an air-containing cell-forming blowing agent, water, a hydraulic cement material and a calcium aluminate non-mineral. Replace as many components as possible with other components, do not delay the onset of initial strength, that is, the time at which setting and hardening begins, do not reduce the strength sufficient for demolding, and further improve the long-term strength and suppress water absorption. Create an aqueous slurry that can release
The goal is to find a way to effectively produce lightweight concrete.

As a result of intensive studies to achieve these objectives, the present inventors discovered that the above objectives could be achieved by replacing a part of the components of calcium aluminate minerals with natural zeolite, and were able to complete the present invention. It was.

That is, the gist of the present invention is to provide a method for producing lightweight cellular concrete using an air-containing cellular cement slurry consisting of water, a foaming agent, a hydraulic cement material, and a calcium aluminate mineral. A method for producing lightweight aerated concrete that replaces natural zeolite.

The contents of the present invention will be explained in detail below.

The foaming agent used in the present invention does not contain foaming agents that react in an aqueous slurry to generate gases such as hydrogen, such as aluminum powder, but surfactants such as soda salts and ammonium salts of alkylaryl sulfonic acids, and lignin sulfonic acid. Foaming agents that normally form an air bubble film, such as so-called metal soaps such as sodium fluoride salts, decomposed products of protein substances, etc., are preferably used. In the case of aluminum powder, for reasons unknown, it cannot be used because it does not have the effect of replacing calcium aluminate minerals with natural zeolite, which is the content of the present invention.

Hydraulic cement materials refer to various types of Portland cement, mixed cement, etc.

Calcium aluminate minerals refer to components that impart rapid hardening, such as alumina cement and mixtures of alumina cement and lime components, but these mainly consist of 3CaO・A40-3 +CaO”AI!
203, %Ca0・7A1203. Ca0・2At
! 203 or a solid solution of a halogen element therein alone or in a mixture thereof, or a mixture or fired product of these and an inorganic sulfate as a component.

Furthermore, natural zeolites have various compositions and crystal structures depending on the ore deposit, such as clinoptilolite, mordenite, and erionite.

Cabascite, Phillipsite, Nigaflight.

Many types of living organisms have been discovered, such as faujasite, ferrylite, natrolite, and squallsite. All of these natural zeolites can be used in the present invention, but clinoptilolite, mordenite, and/or nigawalite are particularly suitable since they are produced in Japan.

These natural zeolites are usually M20 x (Aj?02) y (s to2)
@ z (H2O) [However, M: Na, Ca,
, Mg, Ba or Srn: Valence of M (Here, comparing both elements, S i/A
It is often expressed by a chemical formula such as J) l) m, n, S *Number determined by natural zeolite deposit and type].

The mined raw natural zeolite ore is transferred to the crushing process either as is or after being dried by fire.

The particle size used in the present invention is not particularly limited, but taking into consideration the smoothness of the surface of the concrete molded product, a fine particle size of about 20 mesh or more is suitable.

Conventionally, calcium aluminate minerals have been used in an amount of 2 to 20% by weight based on the total weight of the hydraulic cement material in order to impart rapid hardening. This is a range that can be arbitrarily selected depending on the object to be molded, but if it is less than the lower limit of 2% by weight, the effect is unsatisfactory in terms of imparting rapid hardening, and if it exceeds 20% by weight, the speed of rapid hardening is insufficiently controlled. This results in a lack of reproducibility.

In the present invention, the purpose can be achieved by replacing a part of the calcium aluminate mineral with natural zeolite, but if the replacement is too small, the effect will not be achieved, whereas if the replacement is too large, the hardness will deteriorate rapidly. This is undesirable, and the effect will vary considerably depending on whether or not the same weight is substituted.

As a result of intensive studies on this point, the present inventors found that a more preferable substitution amount range is based on the relationship between unsubstituted calcined natural zeolite ((parts by weight)) It has also been found that the requirements are met at the same time.

The range that simultaneously satisfies these relational expressions is the shaded area in FIG. If too much natural zeolite is added, the viscosity will increase, causing difficulties in slurry production.

Next, two to three examples of the method for manufacturing the air-containing cellular cement slurry containing natural zeolite of the present invention will be given.

However, it goes without saying that the present invention is not limited to these examples of manufacturing methods for cement slurry.

The first example will be described.

In consideration of rapid hardening, first, a mixture of water and a foaming agent is stirred to form an air-containing foam liquid, and while stirring is continued, hydraulic cement material, calcium aluminate mineral, and natural zeolite powder are separately added to this. or mix and add gradually to form the desired cement slurry.

A second example is the following method.

A mixture of water and hydraulic cement material is prepared, a foaming agent is added to the mixture, and air is forced into the mixture while stirring to prepare an air-containing cellular cement slurry.

A desired aqueous slurry can be obtained by gradually adding a mixture of calcium aluminate mineral and natural zeolite to this slurry while stirring.

The third example is a method of replacing the mixture of hydraulic cement, calcium aluminate mineral, and natural zeolite in the second example.

Naturally, natural zeolite may be mixed in advance with hydraulic cement before use.

Incidentally, silica sand, aggregate, fibers, and a setting retarder may be appropriately blended into this air-containing cellular cement slurry as necessary.

The air-containing cellular cement slurry obtained by the method described above is injected into the desired formwork, and the lightweight cellular concrete molded body is demolded in the same manner as conventional methods. It is then transferred to a step of autoclave curing, for example, curing at 180° C. and 10 atm.

The present invention will be explained below using examples.

Examples 1 to 4 [Mixture A] Portland cement 100 parts by weight
Sand 40 Sodium citrate
07 Mixture A consisting of these was gradually added with stirring to an air-containing bubble liquid obtained by stirring and blowing air into Mixture B consisting of 120 parts by weight of water, and this aqueous slurry was added. Furthermore, X parts by weight of alumina cement was added to obtain an aqueous slurry for molding.

The natural zeolites used in this example are clinoptilolite, mordenite, and a mixture of these in the same weight ratio. Clinoprolite, a natural zeolite, is usually (CaNa2) [AJ? 2Si701B) ・6H
20, the natural zeolite mordenite is usually (Ca K2Na2) [AJSi5012]2
Although it is often expressed as 7H20, it goes without saying that the present invention is not limited to these chemical formulas.

The setting speed and initial strength after casting the aqueous slurry for molding,
The long-term strength and water absorption of the concrete formed body thus obtained were determined by measuring the setting properties, the strength after high temperature curing, the area water absorption coefficient, and the overall water absorption rate. By setting the condensation rate to be the time t1 from the time when the air-containing foam aqueous slurry is made to when the slurry is poured into a mold and the water utilization heat generation curve of the hindlimb slurry rises, the broctor penetration resistance value in accordance with ASTM C403 is 30 PSI. The initial intensity was determined by setting the time tp30 at which .

Here, tl is measured as follows. In other words, Figure 2 is a schematic diagram of the setting characteristic curve that commonly appears in rapidly hardening cement slurries, but in actual measurements, this setting characteristic curve changes from the time when a rapid hardening component such as alumina cement is added to create an air-containing foam slurry. Start drawing. The time until the point of intersection of the tangent of the first gradual temperature rise part in the two-stage temperature rise change of the cement slurry and the tangent at the inflection point of the rapid temperature rise part of the next stage. (minutes) was measured as tl.

tp30 was obtained from the penetration resistance measurements as described above.

The long-term strength was measured by preparing a 4° x 40 x 16 strength measurement sample from the prepared cement slurry, which was removed from the mold by leaving it for 50 minutes, and then steam-cured at 180°C for 8 hours.
Cut out a 0 mm piece, leave it at 20°C, 60% RHPa' for 2 weeks, and dry it to determine its bending strength (Fb (kII/cm2))
and compressive strength (F (! (kp/crr?))
was measured and displayed.

Furthermore, the one-sided water absorption coefficient and the whole-surface water absorption rate regarding the water absorption rate have the following meanings. That is, the former can be used as a guide to know the denseness of the capillary structure and the durability of lightweight cellular concrete by measuring the water absorption performance of the capillary of lightweight cellular concrete, and the latter is also a measure of the independence of the fine cell composition of the denseness of the capillary structure. It serves as a yardstick for judging.

The surface water absorption coefficient and the surface water absorption rate were measured by subjecting samples obtained under the same conditions as those used for the long-term strength measurement to a test.

The measurement methods for both are as follows.

[-surface water absorption coefficient]

The test specimen used was a cube cut out at a 10α angle from the center of the molded body and left at 20° C. and 65 l RH until it reached a constant weight.

The specimen was immersed in water at 20 ± 2°C to a depth of 5m7m in an atmosphere of 20°C x 65% RH while keeping it horizontal, and the distance was 30m/m from the bottom of the specimen (i.e., 25m from the water surface).
The time required for the water to be sucked up to ml' m ) was defined as t (1 run), and the amount of wicking was defined as pB).

The one-sided water absorption coefficient C was determined using the following formula.

However, S is the outer surface area of the test specimen in contact with water.

[Overall water absorption rate]

A cube similar to the test specimen for one-sided water absorption coefficient measurement was placed horizontally for 20 minutes.
Immerse the specimen in water at ±2°C, and keep the top surface of the specimen 3° below the water surface.
crn for 24 hours, and then taken out and the overall water absorption rate S (vol) was determined from the water absorption amount using the following formula.

However, W: Weight of the test specimen in a standard dry state 1) Vv: The test specimen was immersed in water for 24 hours, and then the procedures in Examples 1 to 4 were followed.

Examples 5 to 8 Examples 1 to 4 were carried out under the same conditions except that mordenite was used instead of the natural zeolite clinoptilolite. The results are shown in Table 2.

Comparative Examples 5 to 8 Table 2 shows the ratio (weight) of alumina cement to natural zeolite mordenite, but other conditions were in accordance with Examples 5 to 8.

As is clear from the above results, it is clear that some calcium aluminate minerals such as alumina cement are natural. Show a graph.

Patent applicant: Showa Denko Co., Ltd. Agent: Patent attorney Sei Kikuchi

Claims (2)

[Claims] (1) In a method for manufacturing lightweight cellular concrete using an air-containing cellular cement slurry consisting of water, a foaming agent, a hydraulic cement material, and a calcium aluminate mineral, a portion of the calcium aluminate mineral is replaced with natural zeolite. A method for producing lightweight aerated concrete characterized by substitution. (2) When replacing a part of the calcium aluminate mineral with natural zeolite, the ratio of the unsubstituted calcium aluminate mineral (X parts by weight) and the added natural zeolite (Y parts by weight) is X>2 Y>2 Y > -X+12 Y (-X+22) A method for producing lightweight aerated concrete according to claim 1, which simultaneously satisfies the following relational expression.