JPH0153217B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a cement dispersant for hydraulic materials such as cement paste, mortar, and concrete, and more specifically, a cocondensate containing an alkylnaphthalene sulfonic acid as a condensation component and a lignin sulfonate with a reduced content of low molecular weight substances. This invention relates to a cement dispersant which has high water-reducing properties, long-lasting workability, and high strength, and which contains as a main component a mixture of these components and humic acids. Generally, dispersants are used to improve the fluidity of pastes, mortars, concrete, etc. using cement. - There are those mainly based on a formalin condensate of naphthalene sulfonate, and those mainly based on a high formalin condensate of melamine having a sulfonic acid residue, but these have the following drawbacks. In other words, lignin sulfonate-based products have poor short-term strength, so they are used in combination with calcium chloride, sodium sulfate, amines, etc. to improve this, but on the other hand, they may corrode the reinforcing steel. In winter, crystals precipitate, and furthermore, it has air entrainment, curing retardation, and false setting, so it cannot be used in large quantities to reduce the amount of water. In addition, products mainly composed of formalin condensates of β-naphthalene sulfonate and formalin high condensates of melamine having sulfonic acid residues can provide good workability with a small amount of water per unit; have to do more,
Moreover, workability decreases significantly in a short period of time, so sufficient care must be taken when using it. For example, when these additives are used, the workability of the concrete after mixing rapidly decreases, so it is necessary to complete the handling work within an extremely short period of time. When this additive is used in the production of normal ready-mixed concrete, it cannot be transported by concrete mixer trucks or the like. Furthermore, even when manufacturing concrete products in a factory, it is necessary to pay sufficient attention to the reduction in workability of concrete after mixing. The present invention is aimed at solving these drawbacks, and the first invention is a salt of a formalin cocondensate of an alkylnaphthalene sulfonic acid and a compound capable of cocondensing therewith, and the molecular weight in total solid content. A cement dispersant comprising as a main component a treated pulp waste liquid containing lignin sulfonate having a content of 2000 or less components at 30% or less; This is a cement dispersant containing humic acids as a main component. The present invention will be explained in detail below. First, salts of a formalin cocondensate (hereinafter simply referred to as a cocondensate) of an alkylnaphthalene sulfonic acid and a compound cocondensable with the alkylnaphthalene sulfonic acid according to the present invention will be explained. The alkylnaphthalene sulfonic acid preferably has an alkyl group having 1 to 4 carbon atoms. The reason for this is that as the number of carbon atoms increases, air entrainment increases, which adversely affects strength development. Examples of the alkyl group include methyl, propyl, isopropyl, butyl, and isobutyl. Compounds that can be co-condensed with this alkylnaphthalene sulfonic acid are selected from polycyclic aromatic compounds such as naphthalene and anthracene, and their sulfonated products, benzene, toluene, phenol, benzene derivatives such as benzoic acid, and their sulfonated products. One or more types. The amount of alkylnaphthalene sulfonic acid is preferably in a proportion of 0.05 to 0.5 mol, particularly 0.1 to 0.3 mol, per mol of all aromatic compounds in the cocondensate. If the amount of alkylnaphthalene sulfonic acid is significantly smaller than 0.05 mole per mole of fully aromatic compounds, the effect of improving workability etc. will be small;
If the amount exceeds 0.5 mol, air entrainment becomes larger than necessary and has a negative effect on strength development. In addition, the salts of the cocondensate include alkali salts and/or
or alkaline earth salts, specifically sodium salts, potassium salts, calcium salts, and mixed salts thereof. The method for producing salts of the cocondensate according to the present invention includes:
For example, it can be produced by condensing a sulfonated product of a mixture of alkylnaphthalene and naphthalene, or a sulfonated product obtained by reacting alcohol and naphthalene in sulfuric acid with formalin and neutralizing it with a base. Next, we will explain the pulp effluent treatment product (hereinafter simply referred to as the pulp effluent treatment product), which is mainly composed of lignin sulfonate in which the content of components with a molecular weight of 2000 or less in the total solid content is reduced to 30% or less. do. In the present invention, the reason why the content of components with a molecular weight of 2,000 or less in the treated pulp waste liquid is limited to 30% or less is that the content of components with a molecular weight of 2,000 or less is 30% or less.
This is based on the fact that when a cement dispersant containing more than 5% of the total amount of carbon dioxide is used as a cement dispersant, hardening retardation is large and dispersibility becomes low. The molecular weight of the lignin sulfonate can be measured by gel permeation chromatography using silica gel that has been subjected to hydrophilic treatment using standard polystyrene sulfonic acid with a known molecular weight as a standard. In order to obtain such a treated pulp waste liquid, the pulp waste liquid may be used as a raw material, and it may be subjected to various chemical or physical treatments to remove low molecular components. As the raw material, sulfite pulp waste liquid is preferable, and coniferous pulp waste liquid is preferable. Further, as a method for removing low molecular weight components, a dialysis method using a cellulose membrane can be employed in the laboratory, but a method such as an ultrafiltration method is preferable in an industrial setting. In particular, when pulp wastewater is treated by ultrafiltration, it is advantageous because any component can be fractionated according to its molecular size. The ratio of salts in the co-condensate to the treated pulp effluent is
From the viewpoints of high water-reducing properties and sustainable workability, that is, prevention of fluidity deterioration over time, and improvement of strength development, it is desirable that the weight ratio of the latter to the former be from 95:5 to 5:95. The reason for this is that when the proportion of salts in the co-condensate exceeds this range, the sustainability of workability deteriorates and the fluidity decreases over time, and when the proportion of the pulp wastewater treated product exceeds this range, the water-reducing property deteriorates. This is because the amount of air entrained increases and curing is delayed, resulting in insufficient strength development. If a cement dispersant containing the salts of the above co-condensates and treated pulp wastewater as main components is used, high water-reducing properties and long-lasting workability can be imparted to hydraulic materials, and air entrainment is small. The effect is that a high-strength hydraulic material with almost no curing delay can be manufactured. The second invention is one in which the cement dispersant of the first invention further contains humic acids, thereby further improving the sustainability of workability while retaining the characteristics of the cement dispersant of the first invention. be able to. Humic acids used in the present invention include natural humic acids and nitrofumic acids. Natural humic acids are substances represented by naturally occurring corrosive acids, and are substances that exist in young charcoal and soil. In addition, nitrofumic acids are humic acid-like substances obtained by acid decomposing coal with nitric acid to a low degree to reduce the molecular weight and increase the number of functional groups. All of these humic acids are effective, but water-insoluble substances are less effective. The proportion of humic acids is desirably about 1.5 times the total weight of the salts of the co-condensate and the treated pulp effluent at most. The addition rate of the cement dispersant of the present invention to cement is usually about 0.01 to 3%. Furthermore, there is no problem in using the cement dispersant of the present invention in combination with water reducing agents, retarders, hardening accelerators, AE agents, AE water reducing agents, swelling agents, etc. that have been commonly used as admixtures for cement. . The cement dispersant of the present invention may be added by any of the pre-addition method, post-addition method, and divided addition method.In particular, when using the pre-addition method, the change in workability over time is small compared to conventional dispersants. It's advantageous. The pre-addition method refers to a method in which a cement dispersant is added before or during the mixing of hydraulic materials, and the post-addition method refers to a method in which a cement dispersant is added after kneading hydraulic materials for a short time, and the divided addition method This is a method in which the cement dispersant is added to the hydraulic material in portions at regular intervals. The cement used to prepare hydraulic materials includes normal, early strength, ultra early strength, medium heat, white Portland cement, mixed cement containing silica, fried wood, granulated blast furnace slag, etc., expanded cement, calcium aluminate and stone. Examples include rapid hardening cement in which Kou is present, alumina cement, and cement made of granulated blast furnace slag and alkaline irritants such as hydroxides, oxides, carbonates, and sulfates of alkali metals or alkaline earth metals. It will be done. The hydraulic material to which the cement dispersant of the present invention is added can be used for cast-in-place concrete for civil engineering and construction, etc.
For example, piles, poles, concrete pipes, box culverts, and U-shaped grooves produced by arranging and compacting, vibration compaction, or centrifugal force compaction and forming, followed by heat curing such as room temperature curing, steam curing, or autoclave curing. Used as concrete for manufacturing factory products such as steel pipe concrete composites and blocks. The present invention will be explained below with reference to Examples. Note that all parts and percentages described in this specification are expressed on a weight basis. Example 1 The additives shown in Table 1 were dissolved in a predetermined amount of water in the proportions shown in Table 2, and 2.0 kg of ordinary Portland cement and 6.0 kg of river sand from the Sagami River were added thereto and heated at 30°C using a hand mixer. The mixture was mixed for 1 minute to knead the mortar. The mini-slump flow of this mortar is measured immediately after mixing, and the mortar is re-kneaded by changing the water amount until the flow value reaches 260 mm.The water-cement ratio W/C is determined from the required water amount at this time, and the second
Shown in the table. The mortar with a flow value of 260 mm immediately after kneading was allowed to stand after flow measurement, and was kneaded for 15 seconds with a hand mixer every 15 minutes to measure mini-slump flow. Mini slump flow is 15cm high
After filling a slump cone with mortar (5 cm in diameter at the upper opening and 10 cm in diameter at the lower opening), the slump cone was immediately pulled up and the spread of the mortar was measured. The results are shown in Table 2. As is clear from Table 2, it is clear that the Examples are superior to the Comparative Examples in terms of the balance of performance in terms of water reduction, flow change over time, and strength development.

[Table] 100g of β-methylnaphthalene and 400g of naphthalene
was added to 600 g of 98% concentrated sulfuric acid for sulfonation at 160°C for 1 hour, and then 310g of 37% formalin was added dropwise at 100°C to conduct condensation for 5 hours. At this time, when the viscosity increased, a small amount of water was added to lower the viscosity and condensation was continued.
The obtained cocondensate was subjected to liming sodation in a conventional manner to obtain a sodium salt.

[Table] Example 2 Additives with the composition shown in Table 3 were dissolved in 6.24 kg of water, 12.0 kg of ordinary Portland cement, 31.7 kg of river sand from the Sagami River, and 42.0 kg of river gravel from the Sagami River (25 mm or less).
The concrete was mixed using a concrete mixer, and the slump was measured immediately after mixing. Next, let the concrete stand
The slump was re-kneaded every 20 minutes and the slump was measured over time for 60 minutes. The results are shown in Table 4. From Table 4, it is clear that the Examples are superior to the Comparative Examples in the balance of performance in initial slump, slump change over time, and strength development.

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Claims (1)

[Scope of Claims] 1. Salts of formalin cocondensates of alkylnaphthalenesulfonic acids and compounds capable of cocondensation therewith, and ligninsulfonic acid salts in which the content of components with a molecular weight of 2000 or less in the total solid content is 30% by weight or less A cement dispersant comprising, as a main component, a treated pulp waste liquid and a pulp wastewater treated product. 2 Salts of formalin cocondensates of alkylnaphthalenesulfonic acids and compounds capable of cocondensation therewith;
A cement dispersant comprising, as a main component, a treated pulp waste liquid containing a lignin sulfonate having a content of components with a molecular weight of 2,000 or less in the total solid content of 30% by weight or less, and humic acids.