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Significance and Use
4.1 The heat of hydration of a calcium aluminate based castable is liberated over a short period of time (as compared to Portland cement). This makes it easy to measure the heat profile using off-the-shelf thermocouple equipment.
4.3 Factors that should be controlled when comparing two castables include: size, shape and mass of cast object, start temperature of the mix, temperature of environment, and the thermal conductivity of the environment. If these factors are held constant, then the two castables heat profiles can be compared.
4.4 The temperature increase created by the castable exothermic reaction shall be at least 2.0°C more than the normal fluctuation of the laboratory temperature so that the time of this increase is easily discernible to the user.
4.5 Varying the amount of cement in the castable, the amount of water, the type and quantity of admixtures, and so forth, will change the shape, maximum temperature and time to maximum temperature of the curve.
4.6 Following is an example of a curve generated for an LCC (see Fig. 1) that does exhibit two peaks, the first one marking the end of working time. In this curve one could also infer that the start temperature of the mix was 24°C and also that the hydraulic strength gain reaction was significantly started, but not completed by 6 h.
1.1 This guide applies to all castables with a reactive binder system that produces a measurable heat profile during the setting and hardening process. The majority of these systems will have calcium aluminate cement as one component of the binder system.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
C71 Terminology Relating to Refractories
C401 Classification of Alumina and Alumina-Silicate Castable Refractories
C862 Practice for Preparing Refractory Concrete Specimens by Casting
ICS Number Code 91.100.10 (Cement. Gypsum. Lime. Mortar)