JPH0492841A - Cement dispersant - Google Patents

Abstract

PURPOSE:To steeply improve workability of concrete in ultra-high water- reducing region by using an aromatic formalin sulfonate condensate having a fixed molecular weight as a principal component. CONSTITUTION:The aimed cement dispersant is composed of an aromatic formalin sulfonate condensate as a principal component. Said condensate has >=2X10<4> weight-average molecular weight and contains <=50wt.% (of total condensate) condensate having <=1X10<4> molecular weight. Furthermore, said aromatic sulfonic acid is composed of naphthalenesulfonic acid, alkylnaphthalenesulfonic acid or melaminesulfonic acid, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cement dispersant, and more particularly to an ultra-high performance water reducing agent used in cement compositions such as cement paste, mortar, and concrete.

[Conventional technology]

As buildings become taller and underground spaces become deeper,
As the need for high-strength concrete with a compressive strength exceeding 1.000 kg/al increases, the demand for water/cement) (W
There is increasing interest in high-performance water reducing agents that have dispersibility even in the ultra-high water reduction range where the ratio of /C) is 25% or less.

In general, various types of high-performance water reducing agents are known, and representative ones include β-naphthalenesulfonic acid formaldehyde condensate (hereinafter abbreviated as β-NSF) salt,
Examples include melamine sulfonic acid formaldehyde condensate salts. These are used when kneading cement compositions, and these high-performance water reducing agents provide effects such as reducing the amount of water used and imparting fluidity.

[Problem to be solved by the invention]

However, for all of these known dispersants, the usable water ratio to cement is limited to 30%.
It is known that fluidity hardly develops in the ultra-high water reduction range below this range.

Further, a high condensate of an aromatic sulfonic acid formalin condensate salt can also be obtained by adding an excessive amount of formalin and causing high condensation. However, in the case of high condensation by reaction, there are not only problems in production such as decreased stirring efficiency and extended reaction time due to increased viscosity in the reaction tank, but also because it is difficult to control the molecular weight. There is a problem that the width becomes wide, and it is not suitable for effectively obtaining a high condensate with a intentionally designed molecular weight.

An object of the present invention is to provide a cement dispersant that has fluidity even in an ultra-high water reduction region where the ratio of water to cement is 30% or less.

[Means for Solving Problem 1] The present inventors can easily obtain a highly condensed product by fractionation using a polymer separation membrane, etc., and the ratio of water to cement (hereinafter abbreviated as W/C). The present inventors have discovered that it is extremely effective as a cement dispersant even in the ultra-high water reduction range where the amount of water used is 18% to 30%, leading to the completion of the present invention.

That is, the present invention has an aromatic sulfonic acid formalin condensate as a main component, and the weight average molecular weight of the condensate is 20,000 or more, and the proportion of the condensate with a molecular weight of 10,000 or less is 50% by weight of the total condensate.
The object of the present invention is to provide a cement dispersant characterized in that it is less than

The cement dispersant of the present invention can be obtained by removing low condensates from an aromatic sulfonic acid formalin condensation product using a polymer separation membrane.

If the condensate used in the present invention has an average molecular weight of 20,000 or more and a molecular weight of 10,000 or less, the proportion of the condensate is less than 50% by weight,
Although it is effective as a cement dispersant even in the ultra-high water reduction range where the W/C ratio is 18% to 30%, the weight average molecular weight is preferably 20,000 to 100,000. Furthermore, even if the average molecular weight is 20,000 or more, if the proportion of condensates with a molecular weight of 10,000 or less is 50% or more, fluidization will be inhibited and W
It is difficult to use it in the ultra-high water reduction range where the /C ratio is 30% or less, especially 18 to 25%.

The cement dispersant of the present invention exhibits its dispersion effect particularly in the ultra-high water reduction region where W/C is 18% to 30%.
The dispersion effect is exhibited even in the normal water reduction region where W/C is 30% or more and in the ultra-high water reduction region where W/C is less than 18%.

A polymer separation membrane is used to remove low condensates to obtain the high condensates used in the present invention, and ultrafiltration membranes are particularly suitable among polymer separation membranes for this purpose. , polysulfone type (e.g. 5IP-1013 manufactured by Asahi Kasei Corporation)
, polyacrylonitrile type (for example, Asahi Kasei Kogyo A)
HL-1010, CL-1010) ultrafiltration membranes can be used.

Conventionally, a method of removing low condensates using a polymer separation membrane and improving the performance of a dispersant is disclosed in Japanese Patent Application Laid-open No. 59-1.
It is disclosed in Japanese Patent Application Laid-open No. 11964 and Japanese Patent Application Laid-Open No. 139328/1983. However, in the fractionation according to these prior art techniques, the average molecular weight of the condensate to be removed is only a few thousand units, and the resulting condensate cannot be used in the ultra-high water reduction region where the W/C ratio is less than 30%. was difficult. On the other hand, the present invention uses high condensates with a weight average molecular weight of 20,000 or more, in which the proportion of condensates with a molecular weight of 10,000 or less is 50% by weight or less of the total condensate, and the W/C ratio is 18% to 30%. When used in the ultra-high water reduction area of 2000, it exhibits an excellent cement dispersion effect that could not have been expected in the past, and is clearly distinguishable from the prior art as described above.

Although the condensate used in the cement dispersant of the present invention can be used as an acid, it is preferable to use it in the form of a salt. Examples of the cations formed include sodium, potassium, calcium, ammonium, alkanolamines, N-alkyl-substituted polyamines, ethylenediamine, polyethylenepolyamines, and alkylene oxide adducts thereof.

The amount of the cement dispersant of the present invention added is from 0.1 to 0.1% by weight of the solid content relative to the cement of the hydraulic cement composition.
2.5 is good. If it is less than 0.1%, sufficient dispersion effect and slump loss prevention effect on cement particles may not be obtained. Moreover, if it exceeds 2.5%, it may be economically disadvantageous, or the dispersion of cement particles may become excessive, causing breathing or paste separation, or the setting time may increase, leading to a decrease in initial strength.

The cement dispersant according to the present invention can be added to a cement mixture in the form of an aqueous solution or powder, and the time of addition can be determined by tri-blending with cement, dissolving in mixing water, or at the start of mixing the cement mixture. It is possible to add it at the same time as water is poured into the cement, or immediately after water is poured into the cement until the end of kneading of the cement mixture, and it is also possible to add it to the cement mixture that has already been kneaded. Further, the dispersant of the present invention can be added in its entirety at once, or it can be added in several portions.

In addition, when using a water reducing agent together, naphthalene sulfonic acid formalin condensate or its salt, lignin sulfonic acid or its salt, melamine sulfonic acid formalin condensate or its salt, polycarboxylic acid or its salt, polyalkyl carboxylic anhydride Alternatively, one may be mixed in advance with a water reducing agent such as a salt thereof, or one may be mixed with cement or a cement mixture, or one may be mixed with cement or a cement mixture and kneaded before the other is added. May be combined.

In addition, other cement additives (materials) such as sustained release dispersants, AE water reducers, superplasticizers, high performance water reducers, retarders, early strength agents, accelerators, foaming agents, foaming agents, extinguishers, etc. Foaming agents, water retention agents, thickeners, self-leveling agents, waterproofing agents, rust prevention agents, coloring agents, antifungal agents, crack reducing agents, polymer emulsions, other surfactants, water-soluble polymers, swelling agents (materials) ), glass fiber, fly ash, cylinder ash, tallinker ash, husk assini, blast furnace slag, silica hume, silica powder, etc. can also be used in combination.

The weight average molecular weight of the cement dispersant of the present invention was determined using gel permeation chromatography (GPC).
t was determined under the following conditions.

Column: Hydrophilic silica-based TSK gel G400
Two types of combination reference materials: Sv4 and TSK get G20003W (manufactured by Tosoh): Sodium polystyrene sulfonate standard sample for GPC (manufactured by Showa Denki Kogyo) Note: The average molecular weight used in this specification is based on the reference material. Shown as converted molecular weight values.

Eluent: 0.1 molar concentration of IJ chloride aqueous solution and acetonitrile mixed at a volume ratio of 7:3 Eluent flow rate: 0.8 mf/min Column temperature: 40°C Measurement sample concentration: 20.2% by weight Amount of sample injected for measurement = 10 μm Effluent detector: Differential refractometer (manufactured by Showa Denki Kogyo Mari, 5
E-51 type) [Examples] The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

The concrete formulations and materials used in the Examples and Comparative Examples are as shown in Table 1 below.

In addition, in order to compare and study data such as strength, the composition was made so that the slump value was a constant value of 21 cm.

Table 1 Where, C is cement, ordinary Portland cement (specific gravity 3.17), S is fine aggregate, Kinoyo sand (specific gravity 2.5)
8. Coarse particle ratio FM 2.91), G is coarse aggregate.

Crushed stone from Takarazuka (specific gravity 2.61. Coarse particle ratio FM 6.98 >
, W is water and a is S+G.

Method of mixing concrete (Method-1) Mix a cement dispersant in advance and dissolve it in water,
After mixing 501 concrete for 2 minutes at 1001 °C using a tilting mixer, slump and air content were measured. Slump test is JIS^1101, air volume test is JI
S^1128 and compression tests were conducted in accordance with JIS^1108.

(Method-2) Except for adding the cement dispersant separately from the mixing water,
It was carried out in the same manner as method-1.

Production example Naphthalenesulfonic acid (253g), 98% concentrated sulfuric acid (1
0g), water (50g) was placed in a 500-flask, and 8
Warmed to 0°C. Next, at 80-90°C, 37% formalin (140g) was added dropwise over 0.5 hours, and then at 90-90°C.
A co-condensate was obtained by reacting at 100°C for 8 hours (Reference example-
9). The co-condensate was diluted to a 10% aqueous solution, and a polymer separation membrane (manufactured by Asahi Kasei Corporation, ultrafiltration module HL-101) was added.
A high condensate was obtained by performing fractionation using 0 type and CL-1010 type (Reference Example 1). Table 2 shows the compositions of the product of the present invention after fractionation and its comparative product before fractionation, which were obtained in the same manner.

A concrete mixing test was conducted using the products of the present invention and comparative products shown in Table 2 as dispersants.

The test conditions are shown in Table 3. Try again The test results are shown in Tables 4 and 5.

Table 1 Table 1 (Continued) 1) Weight % relative to cement (Solid content) Table 1 (Continued) Table 1) Weight % relative to cement (Solid content) From the results in Tables 4 and 5, the products of the present invention It is clear that this provides an extremely excellent effect in terms of initial dispersibility in the ultra-high water reduction region (W/C ratio = 20%).

〔Effect of the invention〕

The present invention has made it possible to significantly improve the workability of concrete in the ultra-high water reduction region where the W/C ratio is 18% to 30%, especially less than 25%.The cement dispersant according to the present invention can be used in various ways. It can be advantageously used for various purposes.

For example, it is also effective for use in the field of secondary products such as high-strength concrete and centrifugally formed concrete for high-rise buildings with 30 floors or more and buildings with deep spaces.

Procedural amendment (voluntary) September 3, 1990

Claims (1)

[Scope of Claims] 1. The main component is an aromatic sulfonic acid formalin condensate,
A cement dispersant characterized in that the weight average molecular weight of the condensate is 20,000 or more, and the proportion of the condensate having a molecular weight of 10,000 or less is less than 50% by weight of the total condensate. 2. The aromatic sulfonic acid according to claim 1, wherein the aromatic sulfonic acid is composed of one or more sulfonic acids such as naphthalene sulfonic acid, alkylnaphthalene sulfonic acid, melamine sulfonic acid, phenolsulfonic acid, and aniline sulfonic acid (sulfanilic acid). Cement dispersant. 3. The aromatic sulfonic acid formalin condensate is a co-condensate of one or more sulfonic acids such as naphthalene sulfonic acid, melamine sulfonic acid, phenolsulfonic acid and aniline sulfonic acid (sulfanilic acid) and phenol. The cement dispersant according to claim 1.