JP2845358B2 - Admixture for concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compound for civil engineering,
The present invention relates to a concrete admixture which is effective for improving the quality of concrete using poor aggregates in terms of particle size, particle size, etc. in poorly-mixed concrete, civil engineering and architectural formulations having a small unit cement amount.

[0002]

2. Description of the Related Art At present, in the production of concrete, the use of a concrete admixture is indispensable. inside that,
AE water reducing agents are widely used in ready-mixed concrete and various types of concrete for civil engineering and construction that are kneaded in situ in order to improve the properties of fresh concrete and hardened concrete and improve the economics of concrete. Conventionally, as the AE water reducing agent, those mainly used as a lignin sulfonate or a derivative thereof and those mainly containing an oxyorganic acid salt are exemplified.

[0003]

However, when concrete is manufactured using the above-mentioned AE water reducing agent, as the aggregate, crushed sand of inferior quality in terms of particle size and grain size due to the recent deterioration of the aggregate condition. -When crushed stone, sea sand, etc. are used, the concrete state after kneading is poor, material separation occurs, and workability, particularly pumpability, may be reduced. This tendency is a problem particularly in poorly-mixed concrete for civil engineering having a small unit cement amount and concrete having a relatively small unit cement amount even for a compound for construction.

[0004] As a method for solving the above-mentioned problems when a conventional AE water reducing agent is used, there are the following methods. 1. Formulation for improving pumpability and adjustment of aggregate. Use of a concrete admixture that is effective in improving pumpability is conceivable.

[0005] At present, several kinds of admixtures for such purposes are commercially available, but the effect of improving the quality of concrete is not sufficient or has other disadvantages. For example, some thickeners improve pumpability, but depending on the target material, the degree of effect fluctuates sensitively, making it difficult to adjust. On the contrary, if it is added in excess of the optimum amount, the pumping performance is reduced. Further, the thickener is cumbersome to handle and has poor workability. Adjustment of the composition and the aggregate also has problems such as material procurement on the concrete manufacturing side.

On the other hand, the sorbitan fatty acid monoester / ethylene oxide adduct is a known one disclosed for use as an AE agent for fly ash concrete as described in JP-B-63-56184. It is unknown for the purpose of improvement, and the use amount described in the above publication has a large effect as an AE agent, so that the effect of improving pumping property cannot be obtained.

The present invention provides an admixture for concrete having an excellent pumping property.

[0008]

Means for Solving the Problems The present inventors have conducted various studies to solve these problems. As a result, a specific amount of a sorbitan fatty acid monoester / ethylene oxide adduct was added to a conventional ligninsulfonic acid-based AE water reducing agent. The present inventors have found that the compounding can improve the quality of concrete to a range that cannot be achieved by the conventional AE water reducing agent, and reached the present invention.

The present invention provides (1) a concrete admixture comprising 0.1 to 1 part by weight of a sorbitan fatty acid monoester / ethylene oxide adduct per 100 parts by weight of a lignin sulfonate-based AE water reducing agent. (2) The admixture for concrete according to (1), wherein the fatty acid in the sorbitan fatty acid monoester / ethylene oxide adduct has 6 to 22 carbon atoms. (3) The sorbitan fatty acid monoester / ethylene oxide adduct has an ethylene oxide addition mole number of 12 to
50. The admixture for concrete according to (1) or (2), which is 50.

The lignin sulfonate-based AE water reducing agent of the present invention is generally used. The sorbitan fatty acid monoester / ethylene oxide adduct of the present invention can be obtained by a conventional method in the presence of a catalyst. The ester is preferably a monoester, and the amount of the fatty acid is preferably 0.5 to 1.5 mol per 1 mol of sorbite during the synthesis.
If the amount is less than 0.5 mol, there is a problem that the setting of the concrete is delayed and the strength is reduced. On the other hand, if it exceeds 1.5 moles, the effect of improving the pumpability is significantly reduced.

The fatty acid of the sorbitan fatty acid monoester / ethylene oxide adduct preferably has 6 to 22 carbon atoms,
More desirable are lauric acid, stearic acid and oleic acid. Even if the number of carbon atoms is less than 6 or more than 22, the effect of improving pumping performance is not recognized. These may be a mixture of two or more.

The number of moles of ethylene oxide added to the sorbitan fatty acid monoester / ethylene oxide adduct is preferably from 12 to 50. If it is less than this, the pumping performance will not be improved, and if it exceeds this, the air entrainment will increase and the compressive strength of the concrete will decrease.

The concrete admixture of the present invention can be used as a standard at a weight ratio of 0.25% to cement. In addition, sorbitan fatty acid monoester / ethylene oxide adduct is 0.1 to 1 part with respect to 100 parts of lignin sulfonate-based AE water reducing agent. If less than 0.1, the effect of improving pumping property is not recognized, and 1 part or more. Even so, there is a problem that the AE action increases and the strength of concrete decreases.

As the cement, ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, sulfate-resistant Portland cement, blast furnace cement, fly ash cement, silica cement and low heat-generating cement are used. These are admixtures such as silica fume and stone powder, AE agents, water reducing agents, AE water reducing agents, and high performance AEs.
It can be used in combination with an admixture such as a water reducing agent, a shrinkage reducing agent, a setting retarder, a setting accelerator, and a thickener.

[0015]

EXAMPLES The present invention will be described below with reference to examples. (All percentages indicate weight%.)

The materials used and the composition of the concrete are as follows. Water (W): Tap water Cement (C): Asano ordinary Portland cement Specific gravity 3.16 Fine aggregate (S): Crushed sand from Kodama Specific gravity 2.60 FM 2.69 Coarse aggregate (G): Ome-produced sandstone crushed stone Specific gravity 2.70 FM 6.90 Agent A: Sunflow R Admixture B1: Sorbitan monooleate / ethylene oxide 35 mol adduct B2: Sorbitan monolaurate / ethylene oxide 35 mol adduct

As AE water reducing agent, lignin sulfonate-based Sunflow R is A, sorbitan fatty acid monoester.
The ethylene oxide adduct was abbreviated as B, and the results of concrete tests performed using the formulations shown in Table 1 are shown in Table 2.

The slump is JIS A 1101,
Air volume is JIS A 1128, compressive strength is JIS A
It was measured according to 1108.

The pressure bleeding for evaluating the pumping performance is described in the Architectural Institute of Japan's "Concrete Pump Construction Guideline", Appendix 5. Test method of pumpability and rheological constant of fresh concrete (draft) a. Pressure bleeding test method (draft)]. In this test, if the amount of dehydration exceeds the optimum range, the pumpability is determined to be poor.

[0020]

[Table 1]

[0021]

[Table 2]

FIG. 1 shows the results. From the results of the pressure bleeding test, it can be determined that the product of the present invention has adjusted the amount of dehydration to an appropriate value and improved the pumping performance. (The upper and lower limits are based on the guidelines of the Architectural Institute of Japan.)

Further, from Table 2, it is found that the product of the present invention has no adverse effect on other physical properties of the concrete in comparison with the control product 1, and that the product of the sorbitan fatty acid monoester / ethylene oxide adduct is compared with the control product 2 in comparison with the control product 2. It can be seen that when the addition rate is large, the strength of the concrete decreases.

[0024]

EFFECTS OF THE INVENTION By using the product of the present invention, it is possible to use aggregates of poor quality in terms of grain size and particle size in poorly-mixed concrete and civil and architectural formulations with a small unit cement amount in civil engineering formulations. However, it is possible to produce a concrete composition having good pumpability.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of a pressure bleeding test.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Osada, Inventor, Concrete Technology Laboratory, Higashimatsuyama-shi, Saitama 1551 Nippon Paper Industries Co., Ltd. 56) References JP-A-5-58696 (JP, A) JP-A-1-188449 (JP, A) JP-A-1-160853 (JP, A) JP-A-61-270247 (JP, A) JP-A-61-132553 (JP, A) JP-A-59-109662 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 24/18 C04B 24/32 C04B 28/00-28 / 36

Claims (3)

(57) [Claims] 1. A lignin sulfonate AE water reducing agent 100
A concrete admixture comprising 0.1 to 1 part by weight of a sorbitan fatty acid monoester / ethylene oxide adduct per part by weight. 2. The admixture for concrete according to claim 1, wherein the fatty acid in the sorbitan fatty acid monoester / ethylene oxide adduct has 6 to 22 carbon atoms. 3. The admixture for concrete according to claim 1, wherein the number of moles of ethylene oxide added to the sorbitan fatty acid monoester / ethylene oxide adduct is 12 to 50.