| 摘要 |
<p>1432707 Amorphous silica from plant material; cement compositions UNIVERSITY OF CALIFORNIA REGENTS OF 27 July 1973 [28 July 1972] 35827/73 Headings C1A and C1H [Also in Division C3] An anhydrous amorphous siliceous material, suitable for use as a filler and for making cements, is derived from organic plant material, which has a silica content of up to 28% by wt., and comprises 49-98% by wt. silica, the balance being mainly carbon (at least 0À3% by wt.) and non-volatile inorganic constituents (1-5% by wt. other than CaO) of the plant material, the siliceous material being characterized by the complete absence of crystalline silica as determined by X-ray diffraction. The siliceous material is prepared by, for example, heating rice hulls or straws in a furnace at 1050-1100‹ F. for up to 66 hours. Cement compositions having good setting properties and high ultimate strength, can be made using added CaO and/or portland cement.</p> |
