JPS5811381B2 - Additive for hydraulic binders - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to additives for hydraulic binders such as cement and gypsum, and more particularly, to additives for reducing low molecular weight substances and sugar content, The main component is a condensate.

The present invention relates to an additive for hydraulic binders that does not have a curing retarding effect and provides high workability and high strength.

Generally, when producing cement-based concrete, mortar, paste, and gypsum plaster, dispersants are used to improve fluidity and workability. There are those mainly composed of acid salts, those mainly composed of formalin condensates of β-naphthalene sulfonate, and those mainly composed of formalin high condensates of melamine having sulfonic acid residues. There are some drawbacks.

In other words, those mainly composed of lignin sulfonate are
Short-term strength development is poor, so calcium chloride, sodium sulfate, amines, etc. are used in combination to improve this, but on the other hand, the reinforcing steel corrodes, crystals precipitate in winter, and air entrainment occurs. Since it has properties such as hardness, delayed curing, and false setting, it is not possible to reduce the amount of water used by using it in large quantities.

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; In addition, the workability decreases significantly in a short period of time, making it unsuitable for hot mixing, and it is necessary to add in portions during normal use.

The present invention aims to solve these drawbacks, and aims to reduce the content of low molecular weight substances and sugars, and to reduce the content of geninsulfonate and β-naphthalenesulfonate formalin condensate as the main components. The present invention aims to provide an additive for hydraulic binders containing as follows.

That is, the present invention mainly uses a formalin condensate of lysogenin sulfonate and β-naphthalene sulfonate, which contains 25% or less of a low molecular weight substance with a molecular weight of 2,000 or less and a sugar content of 2.5% or less in terms of pentose. The present invention will be described in more detail below.

The ligninsulfonate according to the present invention can be obtained from sulfite pulp wastewater by various methods, such as adding slaked lime to a liquid containing ligninsulfonic acid, and converting ligninsulfonic acid into an insoluble basic salt. A method of adding a polycation to form an insoluble complex,
It can be obtained by extracting and separating saccharides and low molecular weight substances using a solvent, or by ultrafiltration.

In particular, the method of obtaining lignin sulfonate by ultrafiltration is an advantageous method because not only can polymer lignin be recovered individually without using additives, but also sugar can be recovered at the same time.

In the present invention, when this is used as a component of a hydraulic binder additive, the molecular weight of the lignin sulfonate is 2.
000 or less, the sugar content is 25% or less, and the sugar content is 2.5% or less in terms of pentose.

The reason for this limitation in the present invention is that a gel permeation chromatograph using hydrophilically treated silica gel is used to perform various polymerization treatments, measure the molecular weight distribution of geninsulfonate, and classify the sample. When added to hydraulic binders, those with a low molecular weight of 2000 or less cause air entrainment and low dispersibility, and if the sugar content exceeds 2.5% as pentose, curing is delayed and short-term strength is reduced. This is due to the knowledge that the

The preferred molecular weight distribution of lignin sulfonate is 200
0 or less: 10% or less, 10,000 or more: 40
% or more, especially 60% or more, and the preferable sugar content is 1.5% or less as pentose.

On the other hand, condensates are not limited to single condensates, but include polycyclic aromatic compounds such as naphthalene and anthracene and their sulfonic acid compounds, benzene derivatives such as benzene, toluene, phenol, and benzoic acid, and their sulfonic acid compounds, etc. It may also be a formalin cocondensate of

The weight ratio of the lignin sulfonate to the β-naphthalene sulfonate formalin condensate is 2 to 8.
On the other hand, the latter is preferably 8 to 2.

The reason for this is that if the proportion of the β-naphthalene sulfonate formalin condensate is higher than this, adding a small amount of additive will not improve workability, and even if adding a large amount improves this, the subsequent The deterioration over time increases significantly.

On the other hand, if the ratio is small, air will be entrained or curing will be delayed, which will adversely affect strength development.

It goes without saying that the additive of the present invention can be used in combination with water reducing agents, retarders, curing accelerators, AE agents, swelling agents, etc. that have been conventionally commonly used as admixtures for hydraulic binders.

The amount of the additive of the present invention added to the hydraulic binder is usually:
It is about 0.01 to 3%.

As explained above, the present invention is a lignin sulfonate with a reduced content of low molecular weight substances and sugar, and β-naphthalene/
This is an additive containing a sulfonate formalin condensate as a main component. By using this additive, good workability can be achieved even when added in small amounts, and the subsequent change over time is small, and it also prevents air entrainment. Since there is almost no curing delay, it exhibits the effect of providing high strength.

The present invention will be explained below with reference to Examples.

Note that all parts and percentages stated in the specification are expressed on a weight basis.

Example 1 A predetermined amount of the additive shown in Table 1 was dissolved in 270 parts of water, and 600 parts of ordinary Portland cement and 12 parts of river sand were added to the solution.
00 parts were added, and mortar was kneaded at a temperature of 20° C. using a mortar mixer.

The table flow at the time of kneading the mortar and the flow over time were measured at predetermined intervals after the mortar was kept stirring with a mixer.

Further, mortar was separately kneaded under the same mixing conditions, and the air content and compressive strength at the time of kneading were measured.

These results are shown in Table 2.

In addition, table flow and compressive strength are JISR5201,
The amount of air was measured according to ASTM C 158-59.

In addition, additive symbols A-F correspond to the following types.

A Formalin condensate of sodium β-naphthalenesulfonate B Sulfite pulp effluent C Commercially available linosulfonate-based cement dispersant D Symbol B obtained by yeast fermentation to remove sugar E Product obtained by ultrafiltration of symbol B F Comparing the Example and the Comparative Example, which have exceeded the limit, it can be seen that the Example has a high table flow value, a small decrease in flow, and a high compressive strength.

Example 2 A test was conducted under the same conditions as Example 1 except that the amount of additive added was changed.

The results are shown in Table 3. It can be seen that the present invention has a higher table flow value and provides higher fluidity than the comparative example.

Example 3 Concrete was mixed at 20° C. according to the formulation shown in Table 4, and the slump, air content, and compressive strength were measured.

The results are shown in Table 5. The materials were put into a tilting mixer all at once and kneaded for 3 minutes to form concrete. At that time, a commercially available natural resinate-based AE was added to adjust the air volume.
agent was used.

The slump is measured at the time of line rise and thereafter by a tilting mixer adjusted to rotate at 2 times per minute, and measured every predetermined time period, and the compressive strength is the result of concrete lagooning at the time of line rise. .

Comparing the Examples and Comparative Examples, it can be seen that the products of the present invention have high slump, little decrease in slump, and high compressive strength.

Claims (1)

[Claims] 1 Contains as main components lygenin sulfonate and β-naphthalene sulfonate formalin condensate containing 25% by weight or less of low molecular weight substances with a molecular weight of 2000 or less and sugar content of 2.5% by weight or less in terms of pentose. Additive for hydraulic binders.