The bins of asphalt mixing plants are all-welded and modular in construction, permitting easy addition of bins to meet growing needs. Steep bin walls and valley angels allow free flow of aggregates from the feeders minimizing hold up to materials in the corners and bridging with sticky aggregates. The bins supplied with adjustable calibrated gate openings and variable speed feeder drives, together offer total proportional control, greater flexibility and accuracy of operations to drum mix plants.