| 摘要 |
<p>Asphaltic roofing material, such as roll or shingle roofing, employs Class F fly ash as the filler to the asphaltic base material. The fly ash is more readily heated than conventional crushed limestone which has been used as a filler, and further promotes a more rapid cooling of the composite asphaltic web prior to rolling or cutting into shingles. The Class F fly ash comprises between 40% and 70% of the hot asphaltic mixture, by weight. It may be delivered to the roofing plant in a state of elevated temperature from the fly ash source to reduce the requirement for preheating the fly ash or eliminating the preheating step altogether. The slightly acidic content of fly ash discourages the growth of fungus and mold on the roofing material in hot and humid climates, and the resulting shingle has greater overall flexibility and resistance to cracking at low temperatures, as compared to a shingle in which crushed limestone is used as the inert filler.</p> |
