JP2001172064A - Cement admixture and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement admixture capable of diminishing the decline in the initial to mid-term strength of the hardened cement composition despite being formulated with a large quantity of fly ash in cement and thereby of attaining the initial to mid-term strength of the hardened cement composition equal to or higher than the case with using cement formulated with no fly ash. SOLUTION: This cement admixture comprises triisopropanolamine, an oxycarboxylic acid and/or a salt thereof and fly ash. By incorporating cement with this admixture, despite resulting in the other objective cement composition containing a large quantity of fly ash, the initial to mid-term strength of the cement composition after hardened comparable to that of the hardened cement formulated with no fly ash can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture and a cement composition which overcome the drawback of low initial strength when a civil engineering building structure or a concrete secondary product is produced by incorporating fly ash.

[0002]

2. Description of the Related Art In recent years, as the problem of environmental and resource protection has been raised, fly ash, which is a by-product of coal-fired power generation and is becoming a serious problem, is actively added to cement and concrete for use. Is required. However, when fly ash was added, there was a problem that the strength up to a material age of 28 days was reduced as compared with the case where fly ash was not added. In order to prevent the decrease in the initial to mid-term strength, there has been proposed a method of increasing the initial strength of cement concrete by using a cement setting accelerator (Japanese Patent Application Laid-Open Nos. 50-80315 and 55-8055). -71653
However, these methods require complicated operations such as adding the water reducing agent separately from the water reducing agent at the time of kneading the concrete or preliminarily mixing the cement with the cement, resulting in an increase in cost.

[0003]

In general, concrete strength is 28 days old, and the design standard of concrete is concrete. Therefore, cement containing fly ash is not mixed with blast furnace slag which does not decrease in 28 days old strength. It was disadvantageous compared to mixed cement and ordinary cement. Therefore, the use of the fly ash-containing cement is limited, and its use is hindered while having sufficient advantages as a cement admixture, and its proportion in the total cement shipment in Japan is extremely small. Therefore, there has been a demand for a simple technique for increasing the strength development especially at a material age of 28 days even when fly ash is mixed.

[0004]

Means for Solving the Problems The present inventors have conducted various studies in order to solve the above-mentioned problems. As a result, even if the cement contains a significant amount of fly ash, the specific components, triisopropanolamine and It has been found that it is possible to increase the 28-day strength of cement concrete obtained by adding and mixing oxycarboxylic acid and / or its salt. That is, the present invention uses a combination of triisopropanolamine (hereinafter, referred to as TIPA) and oxycarboxylic acid and / or a salt thereof, so that even if a significant amount of fly ash is compounded, the cement concrete has a 28-day strength. Was found to be comparable to cement without fly ash.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The amount of TIPA used in the present invention depends on the ratio of fly ash to be added to cement, and increases as the ratio of fly ash increases. Generally, the proportion of fly ash is not more than 20% by weight, at most about 30% by weight. Assuming that the amount is about 15% by weight, the sum of 85 parts by weight of cement and 15 parts by weight of fly ash, that is, 0.1% with respect to 100 parts by weight of the hydraulic substance.
001 to 0.05 parts by weight, preferably 0.005 to 0.
04 parts by weight. If the amount is less than 0.001 part by weight, a sufficient early strength increasing effect is not exhibited. If the amount is more than 0.05 part by weight, excessive air entrainment may be caused during kneading of cement.

The oxycarboxylic acid used in the present invention is T
It has the effect of improving the strength expression, especially the medium- and long-term strength, together with IPA. Specifically, citric acid, tartaric acid, gluconic acid, malic acid and their sodium, potassium or calcium salts alone or in combination with the above 2 A mixture of more than one species is used. The amount of the oxycarboxylic acid used is 0.005 to 0.3 parts by weight, preferably 0.01 to 0.1 part by weight, based on a mixture of cement and fly ash (about 85:15).
2 parts by weight. If the amount is less than 0.005 part by weight, sufficient strength increase cannot be obtained, and if it exceeds 0.3 part by weight, excessive setting delay may be caused.

In practicing the present invention, TIPA, oxycarboxylic acid and fly ash can be mixed in advance to form a cement admixture, and if necessary, mixed with a certain amount of cement. Further, at the time of kneading the cement containing fly ash, a mixture of TIPA and oxycarboxylic acid may be added, or water may be added to a raw material containing cement, fly ash, TIPA, and oxycarboxylic acid in advance to be kneaded.

[0008] As cement, normal, fast, super fast,
In addition to various portland cements such as moderate heat and low heat generation, various mixed cements obtained by mixing blast furnace slag or silica with portland cement and the like are included. In the case of ordinary Portland cement, it is possible to include various mixed materials such as limestone within the range permitted by JIS.

The fly ash used in the cement admixture and the cement composition of the present invention is not particularly limited, but has a Blaine specific surface area of 1500 to 10,000 cm ² / g, preferably ^{2 to} 10,000 cm ² / g.
000-6000 cm ² / g. Fly ash having a Blaine specific surface area of less than 1500 cm ² / g not only makes uniform mixing with cement difficult, but also reduces pozzolanic activity related to the development of long-term strength. In addition, the increase in the amount of carbon in fly ash is not preferable in terms of production, because air entrainment of concrete is significantly impaired.
If the Blaine specific surface area exceeds 6000 cm ² / g, the amount of AE auxiliary agent added to adjust the amount of excessively entrained air to an appropriate value is not preferable.

The cement admixture and cement composition of the present invention include aggregates such as sand and gravel, blast furnace slag, silica, limestone powder, AE agents, thickeners, rust inhibitors, antifreeze agents, cement polymer emulsions. , Cement swelling agents, setting modifiers, calcium compounds such as calcium oxide and calcium hydroxide, alkali metal sulfates, clay minerals such as bentonite, ion exchangers such as zeolite, hydrotalcite or hydrocalmite, and boric acid One or more of them can be used in combination within a range that does not substantially inhibit the object of the present invention.

[0011]

Examples 1 to 5 and Comparative Examples 1 to 4 85 parts by weight of ordinary Portland cement were mixed with 15 parts by weight of fly ash having a brane specific surface area of 3400 cm ² / g, and 100 parts by weight of a mixture of cement and fly ash On the other hand, the amounts of TIPA and oxycarboxylic acid (hereinafter, referred to as HCA) shown in Table 1 were added to produce a cement composition, and a concrete test was performed. The unit amount in concrete is 250 kg of cement and fly ash
/ M ³ , water 163 kg / m ³ , fine aggregate 880 kg / m ³
Concrete was prepared with 1001 kg / m ³ of coarse aggregate, and slump and compressive strength were measured. The results are shown in Table 1. Separately, fly ash was also used as TI in Comparative Example 1.
Table 1 also shows the results of experiments performed in the same manner as in the example except that neither PA nor HCA was blended. Table 1 also shows the results of experiments in which fly ash was added and only TIPA or HCA was added.

<Materials used> Cement: ordinary Portland cement, Blaine value 33
40 cm ² / g, commercial product fly ash: JIS fly ash, Blaine value 3,400 cm ² / g, commercial product TIPA: commercial product HCAa: Na gluconate, commercial product HCAb: tartaric acid, commercial product HCAc: citric acid, commercial product Aggregate: sand from Himekawa, Niigata Prefecture Coarse aggregate: gravel from Himekawa, Niigata Prefecture Water: tap water AE agent: commercially available <Measurement method> Slump: Measured according to JIS A1101. Compressive strength: Measured according to JIS A 1108.

[0013]

[Table 1]

From Table 1, it can be seen that even with cement containing 15% by weight of fly ash, when TIPA and HCA are used in combination, the initial to mid-strength strength is comparable to concrete without fly ash, especially for concrete structures. It was found that a 28-day strength at the design standard age was obtained.

[0015]

According to the present invention, even if a large amount of fly ash is added to cement, the initial or subsequent time is equal to or higher than the case where cement without fly ash is used.
Medium strength is obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 24:12 C04B 24:12 Z 24:06 24:06 Z 18:08) 18:08) Z 103: 12 103: 12 111: 20 111: 20 (71) Applicant 597146466 Kanden Kako Co., Ltd. 3-95, Showa-dori, Amagasaki-shi, Hyogo (72) Inventor Kazuhide Iwanami 2209, Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture Inside the Aomi Factory (72) Inventor Tadashi Nishimura 100 Kanada, Atsugi City, Kanagawa Prefecture Inside Grace Chemicals Co., Ltd. (72) Inventor Tomohiko Oishi 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Kansai Electric Power Company (72 ) Inventor Mitsuo Tanaka 1-2-1-1800 Benten, Minato-ku, Osaka-shi, Osaka F-term (reference) 4G012 PA27 PB17 PB20

Claims (2)

[Claims] 1. A cement admixture containing triisopropanolamine, oxycarboxylic acid, oxycarboxylate salt or both, and fly ash. 2. A cement composition comprising triisopropanolamine, oxycarboxylic acid, oxycarboxylate salt or both thereof, fly ash and cement.