Development of high-alumina ceramic concrete based on a composite binder

Abstract

Information is provided for preparing high-alumina ceramic concretes based on a combined silicate-phosphate binder. Features are revealed for structure formation of the ceramic concrete developed during hardening, drying and firing; probable chemical reactions that occur are indicated.Recently considerable attention has been devoted to developing and studying composite binders that improve the properties of both ceramic concrete mixes and objects based on them. Composite HCBS binders in the mullite -periclase system [1], and also compacted ceramic concretes of high-alumina composition based on them, have high strength indices, low porosity and improved volumetric constancy during operation [2]. Proceeding from this, the aim of this work is to study the thermomechanical properties of corundum unfired objects, prepared on the basis of both high-alumina cement (HAC) and a composite silicate-phosphate binder developed by us for determining their production properties and development of recommendations for their application.The starting raw material for these studies was electrocorundum ÉB according to TU 2-036-0224450-022-90, highalumina cement according to TU 5739-001-20664498-93, sodium polyphosphate according to GOST 20291, sodium silicate (anhydrous) soluble according to GOST 13079, and fuzed periclase grade PPPBS-96.5 according to TU 14-8234-77.The charge composition of the test corundum unfired objects is provide in Table 1. Grading of unfired objects and naming their components are provided in accordance with recommendations [3].The composite silicate-phosphate binder for ceramic concrete KBV-521 was prepared by technology of mechanochemical binding [4]. Combined grinding of the original binder components, taken in the required ratio (see Table 1), was carried out in a laboratory porcelain mill with a volume of 8 dm 3 to preparation of fractions with a residue on a screen No. 0063 of 0.5 -1.0%. The milling bodies were uralite spheres with a density of 3.2 g/cm 3 . The ratio (by weight) of material -spheres was 1:1.5.In order to study the physicomechanical properties of refractory concrete KBV-611 and ceramic concrete KBV-521 cubic specimens were prepared with a side of 50 mm. The filler and binder for refractory concretes were mixed to visual homogeneity, then the mixture obtained with continuous stirring was moistened with the required amount of water and laid on a plastic mold. Specimens were compacted manually by ramming to total setting of the concrete mix and appearance of cement milk at the surface. Hardening of refractory concrete KBV-611 was carried out first in a moist atmosphere for 24 h in molds, and after extraction from a mold for

Relationship between drying rates and mechanical properties in refractory concretes

“…In conventional castable refractories, water content is a factor that affects the mechanical strength of concrete bonded with calcium aluminate cements. [10][11][12][13][14][15][16][17][18][19][20][21] The smaller amount of water is expected to be added in the mixture. However, the decrease in water content affects their resistance due to their insufficiency to achieve the cement hydration, and flowability, too low hydration to obtain a wellcompacted concrete.…”