| Popis: |
Concrete containing fly ash has been used in many parts of the world for several decades. Various standards and codes have generally limited the use of ASTM Class F fly ash from 20 to 25%. Laboratory studies and field demonstration projects sponsored by CANMET during the last 12 years have shown that concrete containing 55 to 60% fly ash has excellent structural and durability characteristics when proportioned with superplasticizers and at low water to cementing materials ratios. This paper presents some results of research performed under contract to CANMET and some of the practical uses for which the high-volume fly ash concrete system has been utilized in Eastern Canada. The applications discussed include structural concrete, relatively massive machinery foundations, a roller compacted dam, environmental applications such as impermeable shotcrete covers and encapsulation/solidification, and design of mine backfills. The high-volume fly ash system has proven to be an economical construction material which can be mixed, placed and consolidated with conventional concrete construction equipment. Some unique properties such as very low heat generation, low cost, and the possibility to use large quantities of fly ash will expand the future use of the high volume fly ash system. |
