Reference

Prevention of quality deterioration in low-density cement used at high temperature

Prevention of quality deterioration in low-density cement used at high temperature. (Ube Industries, Ltd., Japan). Jpn. Kokai Tokkyo Koho JP 60090860 A2 22 May 1985 Showa, 4 pp. (Japanese). (Japan). CODEN: JKXXAF. CLASS: ICM: C04B022-08. APPLICATION: JP 83-198396 25 Oct 1983. DOCUMENT TYPE: Patent CA Section: 58 (Cement, Concrete, and Related Building Materials) An alkali metal salt 0.05-1.5 wt.% is added to low-d. high-temp. cement contg. a base cement, a d.-adjusting material, and bentonite. The cement has storage stability, and is useful for geothermal and petroleum wells at high temp. and under high pressure. Thus, low-d. cement composed of a base cement 35, SiO2 powder 7, lightwt. fly ash 35, bentonite 4, blast-furnace slag 15, and Ca(OH)2 4 wt.% was mixed with NaHCO3 0.3 wt.%, and stored in a sealed vinyl bag at room temp. for 6 mo. The cement was mixed with a retarder (consisting of a 5:1 Na b-naphthalenesulfonate-formaldehyde copolymer [29321-75-3] and Na gluconate [527-07-1] mixt.) 2.6 parts (based on the cement 100 parts), and water, and kept at 250° to show excellent flowability, and no decrease of compressive strength.

Quick-setting cement

Quick-setting cement. (Denki Kagaku Kogyo K. K., Japan). Jpn. Kokai Tokkyo Koho JP 60054951 A2 29 Mar 1985 Showa, 5 pp. (Japanese). (Japan). CODEN: JKXXAF. CLASS: ICM: C04B022-00. ICS: C04B024-04. APPLICATION: JP 83-164354 7 Sep 1983. DOCUMENT TYPE: Patent CA Section: 58 (Cement, Concrete, and Related Building Materials) Portland cement is prepd. from (1) quick-setting materials contg. monolithic Ca aluminate (I) and anhydrite (II) (I/II wt. ratio 1-2) 15-35, (2) a high-range water-reducing agent 0.1-5, (3) a silicofluoride 0.05-5, (4) an inorg. carbonate 0.1-2, and (5) a hydroxycarboxylic acid or its salt 0.05-1 wt.%. The cement compns. do not gel for 320 min after mixing, and mortar contg. these mixes and sand (mix/sand wt. ratio 1/2) has 3-h compressive strength 3200 kg/cm2. Thus, a quick-setting cement compn. was prepd. by mixing substances composed of high early-strength portland cement, Mighty (high-range water-reducing agent contg. mainly HCHO-Na b-naphthalenesulfonate condensate [9008-63-3] 1.0, citric acid [77-92-9] 0.2, Na gluconate [527-07-1] 0.2, K2CO3 1.0, Na2SiF6 0.5 wt.%, and quick-setting materials consisting of monolithic Ca aluminate (contg. SiO2 3.6, Al2O3 47.7, Fe2O3 2.0, CaO 44.8, MgO 0.3, and TiO2 2.0 wt.%) 1 and anhydrite 1.5 parts 15 wt.%. The compn. 100 was mixed with sand 200, and water 36 parts to show gelation time (at 20° and relative humidity 80%) 38 min, and compressive strength (3 h) 212 kg/cm2.