Analysis of temperature influence on mixing, placement and strength development of calcium aluminate phosphate cement (review)

Recently the refractory industry adopted the necessity for controlling ambient curing temperatures during all processing steps of refractory­concrete installation. The literature review of a temperature influence on the mixing, placement and strength development of calcium aluminate phosphate cement (CAPC) was conducted. As a result of analyzing the literature, it was shown that ambient temperatures of 20 to 27 ºС coincide with the temperature range exhibiting the greatest changes in hydration products, setting time, and strength development. A change of only 5 ºС in curing temperature in this range will produce significant changes in bond structure and physical properties of refractory binders such as alumina cement (AC), high alumina cement (HAC) and CAPC. Preconditioning, mixing, and placement temperatures of up to 27 ºС are the most favorable for providing low H2O requirements and consistently long working times which favor the formation of flaw­free refractory cast installations. The refractory concretes dried and fired strengths developing is critically dependent on the use of the necessary amount of casting H2O required by the specific method of placement to assure installation of a sound lining having minimum structural defects; proper curing conditions to provide development of the desired phases to maximize structural integrity. The good thermal­shock resistance (15 cycles of heating to 1300 ºС and cooling in water) obtained on the CAPC­bonded corundum compositions emanating from their volume stability along with compressive strength 40 MPa and refractoriness 1700 ºС explain their perspective further performance in industry of high temperatures.