JPH0420866B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a setting retarder for rapid hardening cement, which is a cement containing a rapid hardening component consisting of calcium aluminate and slag. Conventionally, for example, 12CaO・7Al ₂ O ₃ , 11CaO・
7Al ₂ O ₃ · CaF ₂ , and a rapid hardening cement that contains calcium aluminate such as CaO · Al ₂ O ₃ and a rapid hardening component consisting of hardening, and is generally called quick hardening cement or super quick hardening cement. As a setting retarder, there are various types, such as those consisting of citric acid and alkali carbonate (Japanese Patent Publication No. 33332/1983).
or gluconic acid and/or tartaric acid or a water-soluble salt thereof, citric acid or an alkali salt thereof, and an alkali carbonate (Japanese Unexamined Patent Publication No. 54-60327)
etc. have been proposed. On the other hand, as technology becomes more sophisticated, for example, emergency repair work for railways and roads requires highly active rapid-setting cement that has even stronger rapid-setting properties than before, that is, high short-term strength. However, this highly active and rapidly hardening cement
The problem was that the curing time was very short, and conventional setting retarders took almost no working time. As a result of intensive studies to solve this problem, the inventor of the present invention found that even with highly active rapid hardening cement, the working time can be freely set, and the strength development at about 3 to 6 hours is not impaired. , successfully developed an innovative setting retardant. That is, the present invention contains 30 to 100 parts by weight of silicate to 100 parts by weight of a mixture consisting of 25 to 35% by weight of oxycarboxylic acids and 75 to 65% by weight of alkali carbonates, and calcium aluminum is added to cement. This is a setting retardant for quick-hardening cement that contains quick-hardening ingredients consisting of nates and phlegmon. The present invention will be explained in more detail below. Examples of the oxycarboxylic acids according to the present invention include gluconic acid, tartaric acid, glyceric acid, malic acid, citric acid, and salicylic acid or salts thereof. Oxycarboxylate salts include sodium, potassium, lithium, calcium, magnesium,
Salts such as iron, zinc, and lead can be used. Among these, it is preferable to use gluconic acid, citric acid, or an alkali salt thereof. In particular, the use of both in combination with alkali carbonates is
Even at low temperatures below .degree. C., it is more preferable because the working time can be easily adjusted and the strength can be developed well. In this case, the combined ratio is preferably 50 to 100 parts by weight of gluconic acid or an alkali salt thereof to 100 parts by weight of citric acid or an alkali salt thereof. The alkali carbonates according to the present invention are alkali carbonates and/or bicarbonates, and the alkali refers to sodium, potassium, lithium, and the like. In the present invention, the ratio of oxycarboxylic acids and alkali carbonates used is 25
The reason for limiting the content to ~35% by weight and 75 to 65% by weight of alkali carbonates is that if the content of alkali carbonates is more than 75% by weight, the short-term strength will not decrease, but the working time will be shorter. On the other hand, if it is less,
This is because although the working time is extended, the short-term strength tends to decrease. As the silicate according to the present invention, silicides such as sodium, potassium, ammonium, magnesium, zinc, iron, and lead can be used. Silicates have long been known as setting retarders for Portland cement, but even when added alone to highly active rapid hardening cement, they have no effect at all and cause instant setting. Further, when oxycarboxylic acids are used in combination with a silicate, the curing time is extended, but the gelation time is fast, and the short-term strength is reduced. especially
This tendency is strong at low temperatures below 10°C. Furthermore, when an alkali carbonate is used together with a silicate, a highly active rapid hardening cement has the disadvantage of instant setting. As described above, the desired effect cannot be obtained by using silicate alone or in combination with oxycarboxylic acids or alkali carbonates, and it is only by using a specific blending ratio of these three components that a highly active rapid hardening cement can be created. of work time without impairing strength development. The amount of silicate used in the present invention is 30 to 100 parts by weight per 100 parts by weight of the mixture consisting of oxycarboxylic acids and alkali carbonates. 30
If it is less than 100 parts by weight, the effect of extending working time is small, and if it exceeds 100 parts by weight, short-term strength development will be reduced. The rapid hardening cement according to the present invention is a cement containing a rapid hardening component consisting of calcium aluminate and slag. As described above, when the setting retarder of the present invention is added to a highly active quick-setting cement, there is an effect that an appropriate working time can be taken without impairing its excellent short-term strength development. Hereinafter, the present invention will be explained in more detail with reference to examples. Example 1 80 parts by weight of Portland cement and 12CaO・
A highly active quick-hardening cement was prepared by blending 20 parts by weight of a commercially available quick-hardening cement material, which is a mixture of amorphous calcium aluminate having a composition of 7Al ₂ O ₃ and anhydrous cement. For 100 parts by weight of this highly active quick-hardening cement,
1 part by weight of a mixture having the composition shown in Table 1 and 100 parts by weight of the mixture were mixed with various proportions of sodium silicate. Furthermore, a mortar was prepared by mixing equal weights of river sand and 35 parts by weight of tap water with 100 parts by weight of highly active quick-hardening cement. According to the test method of JIS R 5201, the hardening time and 3-hour compressive strength of the mortar were measured in a constant temperature room at 20±2°C. The results are also listed in Table 1.

【table】

[Table] <Materials used> Oxycarboxylic acid a: Citric acid Oxycarboxylic acid B: Sodium gluconate Alkali carbonates α: Potassium carbonate Silicate A: Sodium silicate Example 2 17 parts by weight of citric acid, 13 parts by weight of sodium gluconate Example 1 was carried out in the same manner as in Example 1, except that the parts by weight and the type and proportion of silicate were changed to 70 parts by weight of potassium carbonate as shown in Table 2. The results are shown in Table 2. <Materials used> Silicate B: Magnesium silicate C: Ammonium silicate D: Potassium silicate E: Zinc silicate

【table】

[Table] Example 3 The same procedure as in Example 1 was carried out except that the formulation shown in Table 3 was used. The results are also listed in Table 3. <Materials used> Oxycarboxylic acids c: Sodium citrate Oxycarboxylic acids d: Tartrate alkali carbonates β: Potassium hydrogen carbonate

[Table] Example 4 The same procedure as in Example 1 was carried out except that 75 parts by weight of sodium silicate and the formulation shown in Table 4 were used.
The results are shown in Table 4.

【table】

【table】

Claims (1)

[Claims] 1 Contains 30 to 100 parts by weight of a silicate to 100 parts by weight of a mixture consisting of 25 to 35% by weight of oxycarboxylic acids and 75 to 65% by weight of alkali carbonates, and contains cement from calcium aluminate and carbonate. A setting retardant for quick-hardening cement containing a quick-hardening ingredient.