JPS58223653A - Concrete water reducing properties improvement - 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 The present invention relates to a method for improving the water reducing properties of concrete containing a high performance water reducing agent. Concrete as used in the present invention is a general term for cement paste, mortar, and concrete concrete, and high-performance water reducer is a compound that has negative effects on the hardening of concrete, such as delayed setting and air entrainment, even when added in relatively large amounts. It refers to a dispersing agent that can exhibit high dispersibility without giving rise to oxidation, and is broadly classified into polyalkylaryl sulfonate type and high condensate type of triazone derivative based on the chemical structure of the main component. be.

Conventionally, high-performance water reducers have been widely used in the production of high-strength concrete and still-strength concrete products because of their excellent performance. However, the types of cement to which high-performance water reducers are added, The degree of water reduction effect varies depending on the brand and lot difference.
In particular, when the amount used is 0.5% by weight or more based on the solid content of cement, a significant difference appears. For example, when 7.51 cf//m3 of high performance water reducer is added to concrete with unit cement 1470, 9/m3, fine aggregate ratio 68%, and water-cement ratio 60.5%, the slump is 3. 18.5c1rL and 4.8a respectively when using ordinary portland cement from
significantly different from m. This difference is 6% in water-cement ratio.
, strength is 100~150 Icg4/cm”, water reducing agent addition amount is 1.6
It is equivalent to 50 g/m3 in unit cement amount, but the effect of the water agent is different, and assuming a factory that manufactures piles with an average of 5000 m'' of concrete per month, the amount of Some factories have to use a large amount of water reducing agent, equivalent to about 250 ts, which is equivalent to about 22 ts, which is a big burden on the local economy.

In order to solve the above-mentioned drawbacks and further increase the "water reduction rate" of concrete to which a high-performance water reducing agent has been added,
The present invention was completed by discovering that specific amounts of hydrate gypsum and calcium carbonate can be used in combination with different amounts.

That is, in the present invention, 2 to 15% of dihydrite/K is added to the cement content of concrete to which a high-performance water reducer has been added.
This is a method for improving the water-reducing property of concrete, which is characterized by gradually adding calcium carbonate in an amount of at most 5%.

To explain the present invention in detail below, the high-performance water reducing agent has the above-mentioned properties, and commercially available products include Kao Soap ■Product Name [Mighty 100J, [Mighty 1
50J, Monomoto Yushi (Co., Ltd. product/1' name [Ball Fine 51ON], Yama) Yukokusaku Pulp ta
Product name: “Zanflow PS”, Hozorisu Bussan (stock name: “
NL-145 [)J, “NL-400D J
, Showa Denko's product name ``Melment'', etc.

The dihydrate gypsum used in the present invention may be of any type, and the same type of gypsum that has been conventionally blended in an appropriate amount for the purpose of normalizing the setting of cement can be preferably used. To explain this further, conventionally, dihydrate gypsum is used as 3 CaO, AA! in cement. 203 The optimum amount to add differs depending on the amount of alkali, the amount of alkali, and the fineness of the cement. If it is too large, the strength will decrease and the stability of expansion in water will deteriorate. 0% or less, 6.5% or less for early strength cement, 4.5% or less for ultra early strength cement, 6.5% or less for blast furnace cement type A, 3. for silica cement and fly ash cement regardless of type. Each is stipulated by JIS as 0% or less. In actual cement manufacturing, the strength is 0.5 to 1.0 lower than these standard values.
Since the optimum value is found at a low point, and because dihydrate gypsum dehydrates during crushing and becomes hemihydrate gypsum, which tends to cause abnormal aggregation, cement is manufactured by setting a target approximately 1% lower than the standard value. are doing.

In the present invention, by using such dihydrite f in combination with calcium carbonate powder,
Increases the water reduction rate of concrete with added high-performance water reducer,
As a result, the strength has been increased. In the present invention, the effective amount of dihydrate gypsum used differs slightly depending on the type of cement, but regardless of the type of cement, it is necessary to use an amount that exceeds the JIS standard value by at least L.
For the purpose of normalizing setting, 2 to 15% of dihydrate gypsum is added to cement that has already been mixed with dihydrate gypsum. If less than 2% by weight is added, there is no effect of improving the water reduction rate even when used in combination with calcium carbonate, and if more than 15% by weight is added, there will be a large amount of fine powder in the concrete, causing the concrete to become sticky. There will be harm. The preferable addition amount is 5~
It's 10%.

The calcium carbonate used in the present invention does not have a great effect depending on its crystal form and whether it is heavy, light, or chalky, and can be treated to the same extent. A fineness of Blaine of 3,000 crrt2/g is sufficient. Calcium carbonate improves the water-reducing effect of concrete containing a high performance water reducing agent only when it is added in combination with dihydrate gypsum, but no such effect is observed when it is added alone. The amount used is at most 5% by weight, preferably 0.5 to 6% by weight, based on the cement.

The water-reducing property improvement effect of the present invention cannot be achieved by adding dihydrate gypsum alone or by using other forms of gypsum, but can only be obtained by combining it with an appropriate amount of calcium carbonate.

In carrying out the present invention, the type of cement is used regardless of whether it is Bosonland cement, mixed cement, etc., and the post-addition method of high performance water reducer shows even greater effects. Furthermore, since a large amount of dihydrate gypsum is added, in consideration of long-term expansion stability in water, it is preferable to perform steam curing after molding.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 So! 3 content of 2.1% by weight of ordinary Portland cement dihydrate gypsum ground for 5 minutes in a vibrating bot mill (stainless steel'!A), and fineness of 5 D D D cm27
Mix the mortar by changing the amount of limestone powder in g.
The water reduction effect was measured.

The mortar has a cement-sand (river sand of FM 2.95) ratio of 1/1.5, and 1.5% by weight of Kao soap ■trade name "Mighty 150" based on the cement, whose main component is polyalkylaryl sulfonate. The mixture was mixed by adjusting the mortar flow value according to JISR-5201 to 200±5.The dihydrate gypsum and calcilambda carbonate powder were diluted to the cement.

The results are shown in Table 1. Experiment/161-6.11
and 17 are comparative examples, and the others are examples of the present invention. It can be seen that the water reduction effect of the examples is significantly greater than that of the comparative examples.

Table 1 Note) The water reduction effect is expressed as an increase/decrease (1) from Experiment I66, and the water-individual ratio is still (water + 1 Mighty 150J).
/ (Cement, cement + 2-hydrogypsum, or cement +
It is expressed as a weight ratio of gypsum dihydrate + calcium carbonate). 1 ton of water-solid ratio is 30 to 60 kgf/'cr in terms of strength.
This corresponds to about n2.

Example 2 Early strength Portland cement containing 2.9% by weight of SO3, the same dihydrate gypsum and calcium carbonate as used in Example 1, and a high condensate of triazine derivative as a high performance water reducing agent as the main components. Showa Denko ■Product name “Melment F-1”
Mix concrete using 0j, and calculate its slump and 6
Compressive strength was measured for 1 day after steam curing at 5°C for 4 hours.

Table 2 shows the concrete mixing conditions and their results.

As shown in Table 2, Experiment A21 showing an example of the present invention
Compared to experiments A618-20 of comparative examples, the same water-
It can be seen that the slump becomes significantly large despite the solid ratio. In addition, in the example of Experiment itb 22, the water amount was adjusted to have the same slump as in Experiment 418, and the water-solid ratio was approximately 3%.
You can reduce Suito by 1 and get Kokichi.

Claims (1)

[Claims] A method for improving the water-reducing property of concrete, which comprises adding 2 to 15% dihydrate gypsum and at most 5% calcium carbonate to the cement content of concrete to which a high-performance water-reducing agent has been added.