JPS60235753A - Lightweight aggregate coated with synthetic resin - 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 This invention relates to lightweight aggregates for concrete, and more particularly to lightweight aggregates coated with a synthetic resin to prevent water absorption into the aggregate.

As is well known, aggregates have various water-containing states, ranging from no water at all to a state where the particle surface is wet. Its water holding capacity is the workability of concrete.

This must always be taken into account when controlling strength. In particular, lightweight aggregate is porous and has many internal voids, so it is necessary to pay close attention to its water absorption state.

If a large amount of water is absorbed into the lightweight aggregate during the mixing, transporting, and pouring of lightweight concrete, the consistency of the concrete will decrease, and
This causes various problems such as deterioration in durability such as freeze-thaw resistance. In addition, pumping is generally used for pouring lightweight concrete, and a phenomenon has been observed in which the pressure applied during pumping promotes water absorption of lightweight aggregate.

Therefore, it is necessary to devise ways to prevent the water absorption phenomenon of lightweight aggregate after concrete mixing, especially during pumping.

Conventionally, in order to prevent the above-mentioned water absorption phenomenon of lightweight aggregates, measures have been taken to use lightweight aggregates that have sufficiently absorbed water during the refining process, or to allow lightweight aggregates to absorb water before mixing.

On the other hand, in order to improve freeze-thaw resistance, it is desirable to use aggregate with fewer suction channels. However, not only when using lightweight aggregates with low water absorption, but also when using conventional lightweight aggregates that have been pre-absorbed, the phenomenon of pressure water absorption in lightweight aggregates is unavoidable, especially when pumped by high-pressure pumps, resulting in slump. This causes problems such as deterioration.

This invention was made in view of the conventional problems mentioned above, and its purpose is to provide a lightweight aggregate that can suppress water absorption of the aggregate even when pumping lightweight concrete. be.

In order to achieve the above object, the present invention is characterized in that the surface layer of porous lightweight aggregate is impregnated with a synthetic resin, and a waterproof synthetic resin coating is formed on the particle surface.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows a cross section of a lightweight aggregate coated with a synthetic resin according to the present invention. The lightweight aggregate applied to this invention is a conventionally known general natural or artificial aggregate.

In the figure, 10 is aggregate, which contains many air bubbles 1.
2 and capillary pores 14 are present. The surface layer of this porous lightweight aggregate is impregnated with polymer dispersion, etc.
Waterproof synthetic resin wave on grain surface If! 16 is formed.

The synthetic resin coating covers not only the surface of the aggregate 10 but also the pores 14.
．． It has also permeated the country.

This synthetic resin coating 16 prevents external water from coming into direct contact with the porous aggregate 10, thereby inhibiting water absorption of the aggregate 10.

In addition, since the resin of the coating 16 has penetrated into the L pores 14 in the surface layer of the aggregate 10, the surface coating 16 is not only 1J, which can provide sufficient waterproofing and water-blocking effects, but also the surface coating 16 can be damaged by the immediate impact. Even if it is partially destroyed, its waterproof and water-shielding effects will hardly be impaired.

The synthetic resin material for forming the coating 16 is as follows:
It is desirable to use a material that has excellent waterproofness and permeability, has good adhesion to aggregate, and has excellent abrasion resistance.

Such a material is an 8-molecule linear compound,
For example, Sujilene-butadiene rubber
Polymer dispersions such as BR (hereinafter referred to as BR), acrylic synthetic resins Emma and Lusion (hereinafter referred to as PAE) are suitable.

The processing method for forming the synthetic resin coating 16 on the light omega bone 010 is a method in which the lightweight base material 10 is immersed in polymer dispersion or the like for an appropriate period of time, then taken out and dried (immersion method).
A method (spraying method) in which a polymer dispersion or the like is sprinkled on the lightweight aggregate 10 and then dried is simple. In the case of the immersion method, it is sufficient to place the polymer dispersion in a simple water tank or the like and soak the aggregate in it, and the workability is even better if a basket or the like is used so that the aggregate can be easily taken out. In the case of the scattering method, it is necessary to spread the polymer dispersion chopsticks evenly over the aggregate, so the scattering work may be performed while vibrating the lightweight aggregate using a vibrating sieve or the like. Regardless of the dipping method or the spraying method, drying in air is sufficient for drying the polymer dispersion and the like.

In any case, the soaking time, degree of dispersion, or degree of drying may be appropriately selected depending on the type and size of the aggregate used and the type of Bolin-Ice version.

Next, the waterproofing effect of the lightweight aggregate according to the present invention will be specifically explained in comparison with a normal aggregate without the coating 16. The graph in FIG. 2 shows the water absorption properties of the present invention, in which the bone dry amount of granulated artificial lightweight aggregate is used as the lightweight aggregate 10, and a synthetic resin coating 16 is formed with two types of polymer dispersions. The figure shows a comparison of the 1-hour water absorption properties of the same lightweight aggregate without a coating. The film forming process was the same in all cases; the aggregate was immersed in a diluted solution of each polymer disperser for three days, and then dried in the air for 24 hours. The remaining properties marked with black circles are those of the lightweight aggregate without coating 16. These three types of lightweight aggregates were immersed in water, and the relationship between the immersion time and the amount of increase in water absorption of the aggregates was graphed. As is clear from this graph, coating 1 according to the present invention
The increase in water absorption of the base material formed with No. 6 is approximately half that of the aggregate without a coating.

Next, the results of the water absorption test for the three types of lightweight aggregates mentioned above will be explained based on the table below.

In the table below, "without coating" is the absolute dry amount of the above-mentioned granulated artificial lightweight aggregate, and P△E and SDR are those obtained by forming a coating 16 on the aggregate with the above-mentioned type of polymer dispersion. Refers to the product of the present invention. However, the coating process is different from the previous example, and each polymer dispersion contains 90%
After being immersed for a period of time, it was dried in the air for 11 days. The test method was based on the urabone 44 positive coefficient test method of the air chamber pressure method specified in J1S△1128. The test connection is as follows.
As shown in the table, the water absorption rate of aggregate without coating is 1
It is small in relative proportion. The pressure water absorption rates of the two types of aggregates of the present invention are both sufficiently low.

As is clear from this result, the light Ifff according to the present invention
Even when concrete using concrete is pumped, the pressure water absorption phenomenon of the aggregate is much less than before, and negative effects such as slump reduction can be reduced.

As explained in detail above, according to the light Φ aggregate coated with the synthetic resin of the present invention, J3C is also a low water absorption product that takes into consideration water absorption amount A3 and durability, and can be used when concrete is mixed and pump red The water absorption of the aggregate during pouring work is reduced, and the workability of lightweight concrete can be maintained well.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a lightweight aggregate according to an embodiment of the present invention;
FIG. 2 is a test bundling granite in which the water absorption properties of the lightweight aggregate according to the present invention were compared with conventional ones. 10...Lightweight aggregate 12...Air bubbles 14...Capillary 16...Synthetic resin coating patent applicant Hitobayashi Co., Ltd. Agent Patent attorney - Irokigisuke

Claims (1)

[Claims] (1) A lightweight aggregate coated with a synthetic resin, characterized in that the surface layer of the porous lightweight aggregate is impregnated with a synthetic resin, and a waterproof synthetic resin coating is formed on the surface of the particles.