Variacio'n estacional del nivel del mar en el Golfo de Me'xico y Mar Caribe

Refractory materials with high sintering temperatures are made suitable for use as low temperature setting dry vibration cements, ramming cements, gunning cements, and the like by incorporation therein of up to 4% boric acid and a low temperature softening glass or frit. The lower temperature softening frit is finely ground and uniformly mixed with a refractory grain or aggregate. When the mixture is subjected to a temperature as low as 350 DEG C, the frit softens and bonds the refractory grain into a monolithic structure which retains its integrity up to and through the elevated temperatures at which the refractory grains sinter and other high-temperature ceramic bonds form.