Application of ultrasonic pulse velocity technique and image analysis in monitoring of the sintering process

Abstract

Concrete which undergoes a thermal treatment before and during its life-service can be applied in plants operating at high temperature and as thermal insulation. Sintering occurs within a concrete structure in such conditions. Progression of sintering process can be monitored by the change of the porosity parameters determined with a nondestructive test method - ultrasonic pulse velocity and computer program for image analysis. The experiment has been performed on the samples of corundum and bauxite concrete composites. The apparent porosity of the samples thermally treated at 110, 800, 1000, 1300 and 1500ºC was primary investigated with a standard laboratory procedure. Sintering parameters were calculated from the creep testing. The loss of strength and material degradation occurred in concrete when it was subjected to the increased temperature and a compressive load. Mechanical properties indicate and monitor changes within microstructure. The level of surface deterioration after the thermal treatment was determined using Image Pro Plus program. Mechanical strength was estimated using ultrasonic pulse velocity testing. Nondestructive ultrasonic measurement was used as a qualitative description of the porosity change in specimens which is the result of the sintering process. The ultrasonic pulse velocity technique and image analysis proved to be reliable methods for monitoring of microstructural change during the thermal treatment and service life of refractory concrete.

Keywords

• ultrasonic pulse velocity
• sintering
• porosity
• concrete for high temperatures
• image analysis