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How to Improve Pumpability of Lightweight Aggregate Concrete?

How to Improve Pumpability of Lightweight Aggregate Concrete

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Pumping lightweight aggregate concrete is challenging due to the high water absorption of the aggregate in it which results in issues such as segregation, slump loss, inconsistent mix, etc. Therefore, engineers and contractors should consider appropriate strategies to overcome problems associated with pumping lightweight aggregate concrete.

ACI 213R-03 recommends several measures to improve the pumpability of this type of concrete. For instance, adequate and consistent presoaking of the lightweight aggregate to reduce its water absorption capacity is essential to eliminate pumping issues of concrete.

Introducing cementitious materials like fly ash and replacing a small quantity of coarse aggregate with sand enhance the concrete pumpability. The change in the unit weight of concrete should be considered when these techniques are implemented.

How to Improve Pumpability of Lightweight Aggregate Concrete?

Figure-1: Lightweight Aggregate
Figure-2: Slump Test of Lightweight Aggregate Concrete
Figure-3: Pumping Lightweight Aggregate Concrete


How long should lightweight aggregate be presoaked using the sprinkling method?

The minimum time for effective saturation of lightweight aggregate is constant and continuous sprinkling is required for at least three to seven days.

How to check adequate saturation of lightweight aggregate?

The aggregates should be tested for 3 to 4 times a day to check whether the aggregates have been saturated adequately or not.

What is vacuum saturation of aggregate?

Vacuum saturation is conducted by introducing dry aggregate into a vessel from which the air can be extracted. After that, the vessel is filled with water and returned to atmospheric pressure. This process can be carried out only at the aggregate plant.

Is it necessary to test the designed mixture of lightweight aggregate in the field?

Yes, it is necessary to test the designated concrete mixture for pumpability. 

How to reduce concrete pumping pressure?

Pumping pressure can be reduced by limiting the number of bends, employing steel lines instead of rubber lines, and slowing down the placement rate.  

What is the best presoaking method of lightweight aggregate in cold weather conditions?

Immersion of partially cooled aggregate in water and vacuum saturation are the best options to saturate aggregate in cold weather conditions. The use of sprinkling may lead to the freezing of aggregate.

Read More

Ultra-lightweight concrete: materials, properties, and applications

Economy of high-performance lightweight concrete

Applications of high-performance lightweight concrete

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