JP3382961B2 - Concrete water reducing agent - Google Patents

Description

BACKGROUND OF THE INVENTION [0001] Field of the Invention The present invention has small air entrainment,
Less change of concrete fluidity with time and inexpensive
The present invention relates to a concrete cleat reducing agent which can prevent a decrease in the strength of concrete . [0002] In concrete, cement, water, fine aggregate, is whether we constructed coarse aggregate 及 beauty entrainment empty feel. A moderate amount of entrained air increases the resistance of the hardened concrete to freezing and thawing , and improves the fluidity of the unconsolidated concrete. Adjustment of amount of air entrained is also a water reducing agent having an air entraining (AE water reducing agent) is carried out by water-reducing agent used in combination air entraining agent (AE agent). The widely used as an AE water reducing agent is a sulfite waste liquor, there is a high air entrainment effect on lignin sulfonate its main component. AE
If the use of the water reducing agent alone does not achieve a sufficient amount of air, an air entraining agent (AE agent) is added. [0003] In general, an appropriate amount of air for concrete is defined by JA.
SS 5 (Architectural Institute of Japan Standard Specification for Construction Work, Concrete Work) 2.6%, as described in “Rules on Materials and Mixing to Ensure Durability”. Exceeding the appropriate air volume range will impair the durability of the concrete. When the amount of air is small, the resistance to freezing and thawing is not sufficient, and when the amount of air is large, the strength is reduced. [0004] However, depending on the concrete material and mixing conditions, the use of an AE water reducing agent often reaches an excessive air entrainment amount.
As a result, the design strength of the hardened concrete cannot be obtained.
Therefore, a low air-entraining water reducing agent having a large adjustment range of the amount of air is desired. Depending on the concrete materials and mixing conditions, even if a sufficient amount of air cannot be obtained when using a low air entraining water reducing agent, the necessary amount of air can be easily obtained by adding an AE agent in that case. [0005] Water reducing agents with low air entrainment include naphthalene sulfonic acid formalin condensate, melamine sulfonic acid formalin condensate, and the like. And its use is limited due to its high cost. Also, reducing the amount of the AE water reducing agent containing sulphite pulp effluent as a main component can be a means of suppressing the amount of air, but impairs the water reducing property, which is the most important performance of the water reducing agent. Therefore, the development of an inexpensive water reducing agent that has low air entrainment and little change over time in the fluidity of concrete is desired. [0006] The present invention, in such circumstances, includes those having a molecular weight of at least 20,000.
The content of Manai lignosulfonate 45% or less sulphite pulp drainage has reached the present invention is an inexpensive cement water reducing agent is less fluidity of the aging of the small and concrete air entraining property. The composition of the sulphite pulp drainage lignosulfonate, be reducing saccharides, mainly surface activity is high lignin sulfonate to have an air entrainment of is a sugar-modified product 及 beauty inorganic salts which like The amount is usually around 60% of the drainage. And sulfite pal
The molecular weight distribution of lignin sulfonate in the wastewater
It is known that it is almost the same from 0 to 10000
("Lignin Chemistry: Basics and Applications", Junzo Nakagawa
Authored, published by Uni Publishing Co., Ltd. on May 25, 1990, No. 49
(See Figure 9.2 on page 8.) The present invention has a molecular weight of at least 20.
<br/> content of lignosulfonate containing no to exceed 000 is to provide a cement water reducing agent consisting mainly of 45% or less of the sulphite pulp drainage. If the content of lignin sulfonate is large, it has excessive air entrainment, so that the content is preferably 45% or less, more preferably 40% or less. In the present invention, the molecular weight is at least 200.
The sulphite pulp effluent having a lignin sulfonate content of not more than 45% and containing no lignin sulfonate having a molecular weight of not more than 45% has a molecular weight of at least 45% by an ultrafiltration membrane or dialysis membrane.
It can be obtained by using a permeate from which a high molecular weight region exceeding 20,000 has been removed. Industrially, it is desirable to purify with an ultrafiltration membrane. The molecular weight cut off of the ultrafiltration membrane can be arbitrarily selected so that the content of lignin sulfonate having a molecular weight of at least 20,000 or less can be reduced to 45% or less. Heretofore, it has been known that a high molecular weight region obtained by fractionating a sulfite pulp effluent by an ultrafiltration membrane or a dialysis membrane is used as a cement dispersant. However, ultrafiltration of conventional sulfite pulp effluent
Of cement dispersant obtained by fractionation treatment with membrane or dialysis membrane
The average molecular weight is about 30,000 ("Cement Concree
No. 479, January 1987, p. 23).
However , the low molecular weight region is known to be used as a binder for fertilizers and agricultural chemical granules, but is not used as a low air entrainment cement dispersant. Although the product of the present invention has a lower ligninsulfonate content than the conventional product, the water reducing performance does not decrease. This is due to the increase in the content of the modified saccharide having a water-reducing property higher than that of the lignin sulfonate. And lignin sulfone
Increased content of modified sugars with lower surface activity than salt
As a result, the air entrainment is reduced. Further, since the reducing saccharides 及 beauty inorganic salt in water reducing property is exactly not contribute component leads to a decrease in extremely large a water reducing property, it is desirable to remove as needed this like. The reducing saccharide can be modified to a water-reduced saccharide by heating under alkaline conditions. Further, the inorganic salt can be separated and removed as a precipitate after its solubility is reduced by concentration or cooling. Cement water reducing agent of the present invention can be used as an AE water reducing agent 及 beauty water reducing agent and is also effective in combination with other dispersants. The present invention will be described with reference to concrete test results. Example 1 A calcium-based sulfite pulp effluent was adjusted to pH 5.0, fractionated by an ultrafiltration membrane having a molecular weight cut-off of 20,000, the permeate was concentrated, and the precipitate was centrifuged off to remove the product of the present invention. 1
Got. Molecular weight of 20,000 or less of calcium lignosulfonate content at this time is 35% as shown in Table 1. Incidentally, lignin sulfonate content reducing saccharides contained sulfite pulp drainage thereto, and up to exhaustively dialyzed total sugar modified product 及 beauty inorganic salt is less than 1%, high purity lignin sulfonate obtained It was calculated from the methoxyl group of the acid salt.
This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Example 2 A sodium-based sulfite pulp effluent was adjusted to pH 5.0, fractionated by an ultrafiltration membrane having a molecular weight cut-off of 5000, the permeate was concentrated, cooled to 5 ° C., and precipitated. The product was decanted to obtain product 2 of the present invention. The molecular weight at this time is 500
0 following lignin sodium sulfonate content is 31% as shown in Table 1. This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Example 3 A magnesium-based sulfite pulp effluent was adjusted to pH 5.0, fractionated with a dialysis membrane having a molecular weight cut-off of 5000, the permeate was concentrated, cooled to 5 ° C., and the precipitate was separated. Decantation was performed to obtain the product 3 of the present invention. The molecular weight at this time is 5000
The following lignosulfonate magnesium content is 29% as shown in Table 1. This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Example 4 A calcium-based sulfite pulp effluent was adjusted to pH 5.0, fractionated by an ultrafiltration membrane having a molecular weight cut off of 20,000, the permeate was concentrated, and calcium hydroxide was further concentrated. 5% of the solid content was added and heat treatment was performed at 80 ° C. for 2 hours to obtain a product 4 of the present invention. Molecular weight of 20,000 or less of calcium lignosulfonate content at this time is 37% as shown in Table 1. This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Example 5 After the sodium sulphite pulp effluent was adjusted to pH 5.0, it was fractionated by an ultrafiltration membrane having a molecular weight cutoff of 5,000, the permeate was concentrated, and sodium hydroxide was further concentrated in the concentrated liquid. 5% was added to the solid content, and the mixture was heated at 90 ° C. for 2 hours. After cooling to 5 ° C., the precipitate was decanted to obtain a product 5 of the present invention. Molecular weight of 5000 or less of lignin sodium sulfonate content at this time is 36% as shown in Table 1. This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Example 6 A magnesium-based sulfite pulp effluent was adjusted to pH 5.0, fractionated with a dialysis membrane having a molecular weight cut-off of 5000, and the permeate was concentrated to obtain a product 6 of the present invention. Lignosulfonate magnesium content at this time is 27% as shown in Table 1. This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Comparative Example 1 A calcium-based sulfite pulp effluent was adjusted to pH 5.0 and then concentrated (control product). Lignosulfonate calcium content at this time is 59% as shown in Table 1. This was added to cement in an amount of 0.20% to produce concrete with the composition shown in Table 2. Comparative Example 2 0.15% of the concentrated liquid of Comparative Example 1 was added to cement, and concrete was produced according to the composition shown in Table 2. Comparative Example 3 A commercially available naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation, trade name: Mighty 150) was added to cement in an amount of 0.20% to produce a concrete according to the composition shown in Table 2. Next, the amount of lignin sulfonate of the product of the present invention is shown. [Table 1] [0019] The use of concrete material 及 beauty formulation is as follows. Materials that easily entrain air were used. Materials used Cement (C): Fine Portland cement mixed with 3 kinds of fine aggregate (S): Kisarazu land sand (specific gravity 2.59, FM2.6
6) Coarse aggregate (G): crushed stone from Yamaguchi (specific gravity 2.70, FM 6.60) Water (W): tap water [Table 2] Knead with a 100 l mixer for 3 minutes.
After 0 and 60 minutes, the slump was measured, and the time-dependent change in fluidity in the stationary state was observed. Slump, the measurement of the air volume 及 beauty strength was carried out in accordance with JIS. [Table 3] From the concrete test results shown in Table 3, the sulphite pulp effluent of Comparative Example 1 has high air entrainment and therefore low strength, and is difficult to use with this material. The product has an air entrainment in an appropriate range, does not show a decrease in strength, and can be used as an AE water reducing agent.
Comparative Example 2 shows that when the amount of air added to the sulfite pulp effluent was reduced to suppress the amount of air within an appropriate range, the slump was small and the water reduction was insufficient. Also, the naphthalenesulfonic acid formalin condensate has low air entrainment,
Also Oh evident from Comparative Example 3 that liquidity aging is great
You. [0024] As described above in detail, according to the present invention, concrete water reducing agent consisting invention, low air entraining property and less fluidity of the aging of concrete, yet inexpensive, a reduction in the strength of the concrete It has been successfully prevented and has a high industrial contribution.

Continuing from the front page (72) Inventor Susumu Mihara 2-8-1, Iida-cho, Iwakuni-shi, Yamaguchi Pref. Sanyo Kokusaku Pulp Co., Ltd. Production Engineering Laboratory (72) Inventor Tadahiro Ishimoto 2--8, Iida-cho, Iwakuni-shi, Yamaguchi No. 1 Sanyo Kokusaku Pulp Co., Ltd. Production Engineering Laboratory (56) References JP-A-57-100961 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 2/00 -28/36 D21C 11/00

Claims (1)

(57) [Claim 1] The molecular weight is more than at least 20,000
Concrete water reducing agent content of lignin sulfonate as the main component 45% or less of sulfite waste liquor which does not contain one.