Release Time：2018-03-29
Low cement castables refer to castables with lower cement content. The cement dosage of refractory cement castables is generally 15%~20%, while the cement dosage of low cement castables is about 5%, and some even decrease to 1%~2%. The purpose of reducing cement dosage is to improve the fire resistance performance of castables.
Low cement castables achieve good performance by adding several special raw materials: firstly, pure calcium aluminate cement, due to the high content of effective mineral CaO · Al2O3, can achieve the required strength with less addition. The second silica fume, with a SiO2 content between 93% and 98% and an average particle size of about 0.5 μ M’s glass microbeads. After adding silica fume, the flowability of the castable is good, the molding water requirement is low, and the sintering temperature is low, which improves and avoids the performance after heat treatment. Thirdly, alumina micro powder is relatively easy to participate in the reaction and improve the material’s fire resistance. Fourthly, water reducing agent, which can adsorb on the surface of the powder and generate electrostatic repulsion to disperse the powder, further exerting the effect of micro powder.
(1) Anchor nail welding. Use a pistol type welding gun to clamp the anchor nails with the matching anchor nail chuck, and weld them towards the water-cooled beam (column) according to the design spacing.
(2) Ceramic fiber felt wrapping and surface treatment. Wrap the pre processed block shaped ceramic fiber felt on the corresponding water-cooled beam (column), tightly wrap the ceramic fiber felt on the water-cooled beam (column) with a spiral of z2 galvanized iron wire, and then spray hardening agent on the surface of the ceramic fiber felt. Wait for it to dry and harden, forming a hard shell on the surface of the felt before pouring construction.
(3) Template installation. To ensure the shape of the lining wall after pouring and the fumigation and reuse of the template, a 4mm thick steel plate is used to make a fixed steel template. The steel template should be installed from bottom to top, and the lower end of the installed template should be clamped onto the poured lining wall.
(4) Mixing of low cement castables. Compulsory mixer must be used for mixing, clean water should be used, and the water temperature should be between 10-25 ℃; Strictly follow the mixing ratio provided in the material instruction manual for ingredients and water addition; To overcome the uneven particle size distribution of dry aggregates during transportation; Mix dry for 1 minute before adding water and stir for 4-5 minutes.
(5) Pouring. The mixed pouring material is quickly transported to the pouring site, and the pouring material is poured into the mold using a small shovel and a specially designed feeding hopper. When pouring the beam, the material should be cut from one side of the template to prevent gaps in the lower part of the beam. When cutting, it is necessary to prevent the wrapped ceramic fiber felt from breaking or falling off. After filling up the material, start the vibrator, and the material surface will sink during vibration. Add the material in a timely manner. When the pouring material surface no longer sinks or there are no bubbles escaping from the surface, stop the vibration. The vibration time is generally 2 minutes.
(6) Demoulding and repair, when the temperature inside the furnace is 10-25 ℃, the mold can be removed 8 hours after pouring, and the poured material will naturally maintain health after demoulding. The pouring quality should be checked in a timely manner. General defects should not be treated, but important parts and major problems should be repaired to ensure that the lining meets the production process requirements.
Low cement castable is a high-tech refractory material developed on ordinary castables using rheological principles, the theory of the most compact packing, and ultrafine powder technology. It has low porosity and pore size