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A laboratory study was undertaken to evaluate the in situ performance of self-compacting concrete (SCC) compared to a conventional compacted concrete (CCC) of similar strength in reinforced concrete T-beams. As an additional feature, the desired SCC properties were obtained partly by the introduction of fly ash to enable a SCC, of strength similar to the conventional concrete, to be attained at little or no additional cost. The performance of SCC in the T-beam was assessed in terms of homogeneity and uniformity, uniformity of surface hardness, in situ compressive strength, and likely durability. Further, the structural responses of the T-beams in terms of initiation and propagation of structural cracks, cracking pattern, mode of failure, and load versus deflection behavior were investigated under single point loading. The study suggests that SCC performs at least as well as CCC in terms of homogeneity, uniformity of construction, and structural responses, and is likely to have improved durability. DOI: 10.1061/(ASCE)0899-1561(2009)21:3(103) CE Database subject headings: Concrete; Fly ash; Structural response; Compressive strength; Durability; Compaction; Beams.

Multidimensional simulations of both flue gas and fly ash (solid particle) flows with application to erosion prediction in the economisers of coal-fired power utility boilers are reported. A computer code specifically designed for power utility boilers, DS4PUB (Design Software for Power Utility Boilers), was used for the calculations. The major area of erosion often occurs at the economizer of the boiler and depends on the particulate velocity and concentration so that computational results include the economizer inlet distribution of the mean flue gas and particulate velocities, and fly ash concentration. The computer code was validated by comparisons with previously available experimental data and recently performed measurements for flue gas flow velocity, dust burden, and erosion rates at the inlet of economizers in large operating power stations. The results of the multidimensional simulations agreed reasonably well with the experimental measurements. An important finding of this stud), is that the transverse location of maximum erosion in the economizer tube bank strongly depends on the upstream geometric design of the boiler. For boilers with a shorter turning flow path, the maximum erosion is found to be close to the rear wall of the economizer because both the maximum particulate velocity and concentration occur in this region. For configurations with a long flow path, which includes a splitter plate, the maximum erosion region was found to be closer to the front wall of the economizer, mainly due to the high flow velocity in this region. A relatively high erosion area close to the side and rear wall was also found because of the high concentration of large fly ash particles in this area. Interesting features of fly ash flow in multidimensional complex boiler geometries such as concentration distributions for different fly ash particle sizes are also discussed.