concrete gradation with the variety and size of selected aggregates related

Precast concrete plant gravel sand as aggregate best, but it works in the field, often with gravel majority. Most pump specification to maximum aggregate size is defined as the maximum size pebbles 40mm, gravel 30mm, there are differences between the two. As a general rule, pumping concrete in the rubble of a diameter not exceeding duct diameter of 1/4, pebble diameter of not more than 1/3. Such as the use of lightweight aggregate, with particular attention to its water absorption, because when the water in the pumping lightweight aggregate capacity, will directly affect the slump of concrete to concrete delivery more difficult. In case of such a situation, you should do a few tests to adjust the content of the concrete, or the lightweight aggregate pre-absorbent. d. and aggregate size distribution, particle aggregates concrete mix plant on a great impact on the pumping capacity, such as aggregate deviation from the standard size is too large pumping capacity will reduce, or even cause plugging. Sand the rate of the larger impact on the pumping capacity, sand the rate of 40% to 50% pumping better. In addition, attention should be paid on the sand particle size, 0.3mm fine sand below the amount should normally be more than 15%.