JPH075342B2 - Cement-based cured product - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cement-based cured product blended for reuse of a ground product of the cement-based cured product.

[Background Art] For cement-based, slag-cement-based, and fly-ash-cue-based cured products (collectively referred to as cement-based cured products), reuse defective products such as cement-based cured products and cutting waste. Therefore, these crushed products are blended as one of the raw materials. However, the cement-based cured product produced by blending the crushed product of the cement-based cured product in this manner has a problem that the water absorption rate becomes high and the water-absorption expansion largely occurs.

[Object of the Invention] The present invention has been made in view of the above points, and a cement-based cured product capable of preventing a large amount of water-absorption expansion from occurring when compounding a ground product of the cement-based cured product. It is intended to provide.

DISCLOSURE OF THE INVENTION However, the hardened cementitious material according to the present invention is produced by making a blended material containing cement as a main component and a crushed product of the hardened cementitious material having a water repellent adsorbed on the surface thereof. The present invention is described in detail below.

Cement-based hardened material is mainly composed of cement, and if necessary, hydraulic components such as slag, fly ash, and gypsum, organic fibers such as vinylon and nylon, and inorganic fillers such as barlite and calcium carbonate. Then, these can be dispersed in water, and the slurry thus prepared can be produced by wet papermaking.
Here, in order to recycle defective products such as cement-based cured products and cutting waste, this cement-based cured product is crushed, and this crushed product is used as an inorganic filler compounded in the above slurry. Reuse of a product A crushed product is used with a water repellent adsorbed on the surface. As the water repellent, those containing stearic acid as a main component can be used. For example, the water repellent is adsorbed on the surface of the reused pulverized product by adding the water repellent to the recycled pulverized product and mixing them. be able to. The addition amount of the water repellent is preferably set to 0.1 to 5.0% by weight based on the total solid content of the cement-based cured product.

A cement-based cured product obtained by blending a reused pulverized product having a water-repellent agent adsorbed on the surface as described above, wherein the pulverized product absorbs water by the water-repellent agent adsorbed on the surface of the pulverized product. In addition, it is possible to prevent the cement-based cured product from absorbing and expanding due to the expansion of the crushed product due to the absorption of water. Here, the water absorption expansion of the hardened cement product is mainly caused by the water absorption expansion of the recycled crushed product. Therefore, in order to suppress the water absorption expansion of the hardened cement product to a low level, the water repellent is It is necessary to adsorb to the surface of the crushed product to be used, and even if the water repellent is adsorbed to another inorganic filler or the like for use, a large effect cannot be obtained.

Next, the present invention will be further described with reference to Examples.

Examples 1 to 4 Cement-based slurries were prepared by dispersing the components of the formulations shown in Table 1 in water, and the slurries were wet paper-formed, dehydrated and cured to obtain hardened cement-based products.
Here, the amount of the stearic acid-based water repellent adsorbed to the recycled crushed product of the cement-based cured product was set to be 2% by weight based on the total solid content.

Comparative Example 1 A cement-based slurry was prepared by dispersing each component in water according to the formulation shown in Table 1 by using a recycled crushed product of the cement-based cured product without being treated with a water-repellent agent.
Cemented hardened materials were obtained in the same manner as in Nos. 4 to 4.

Comparative Example 2 Reusable crushed product of cement-based hardened material was used without being treated with a water repellent and calcium carbonate having a stearic acid water repellent adsorbed on the surface was used instead (adsorption of stearic acid water repellent). 2% by weight based on the total solid content), 1st
Cement-based slurries were prepared by dispersing each component in water according to the formulation shown in the table, and the cement-based cured product was obtained in the same manner as in Examples 1 to 4 below.

The water absorption rate and the dimensional change rate of the hardened cementitious materials obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured. The results are shown in Table 1. The dimensional change rate in Table 1 is expressed as a percentage calculated from the dimensional change before and after the test piece was allowed to absorb water for 24 hours at a constant temperature of 60 ° C.

As a result of Table 1, it was confirmed that the water absorption rate and the dimensional change rate can be reduced and the water absorption expansion can be reduced in each Example as compared with Comparative Example 1 using no water repellent. To be done. Further, when a water repellent agent is used, as in Comparative Example 2, when the water repellent agent is adsorbed on the inorganic filler calcium carbonate, the water absorption coefficient cannot be reduced but the water absorption expansion cannot be reduced. It is confirmed that it is necessary to adsorb to the crushed product of hardened cementitious material.

[Effects of the Invention] As described above, in the present invention, when the crushed product is blended for reuse of the hardened cementitious material, it is blended with the water repellent adsorbed on the surface. Since the material is made into a paper, it is possible to prevent the crushed product from absorbing water by the water repellent adsorbed on the surface of the crushed product and reduce the expansion of the crushed product due to this water absorption. It is possible to prevent the cured product from absorbing water and expanding.

In addition, since a crushed product of a cement-based cured product is used as the crushed product, even if the crushed product does not cause any action or change by the water repellent at the time of papermaking, it is mainly composed of the same type of cement as the crushed product. The mixture as a component can be uniformly mixed, and in the cement-based cured product obtained by paper-making this composition, the pulverized product can be uniformly present without any trouble, and the entire cement-based cured product can be obtained. It can be held in a uniform state.

Claims (1)

[Claims] 1. A hardened cementitious product, which comprises a cement as a main component and is mixed with a crushed product of a hardened cementitious product having a water-repellent agent adsorbed on the surface of the cement.