Abstract At present, chemical admixtures are usually added in concrete mixtures when all ingredients are mixed together either by one-time input or in batches for various purposes. The present study proposes a new method for lightweight aggregate (LWA) concrete or combined aggregate concrete, wherein porous and hydrophilic LWA are presoaked in chemical admixture solution with the appropriate concentration. Poly carboxylic acid-based-super plasticizer and setting retarder were prepared and added individually in combined aggregate concrete in different ways, as follows:(1) one-time direct admixing into a concrete mixer; (2) blending in concrete mixture in batches; and (3) absorbing into LWA particles in advance. Time-dependent slump and setting times of concrete mixtures were investigated, which proved that chemical admixtures can be stored in porous aggregate particles beforehand by means of presoaking. LWA, with the internal pores as sustained-release capsules, become temporary carriers of water and chemical admixtures. Once relative humidity in the concrete mixture falls, the molecules of chemical admixtures gradually move out with water migration to play a persistent part in, for example, successful slump loss reduction or setting time adjustment.
Fund:Supported by the National Natural Science Foundation of China(No.51302020); The Technology Plan Project of Ministry of Transport of China (No. 2015319825180)
CHEN Yu,DENG Yi-fan,LIU Yang. Carrier and Delayed Release Properties of Lightweight Aggregates for Chemical Admixtures[J]. Journal of Highway and Transportation Research and Development, 2016, 10(3): 67-73.
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2016, Vol. 10 
