文摘
The pores of lightweight aggregates (LWAs) cause problems with the quality control and pumpability of lightweight aggregate concrete (LWAC), but offer a number of advantages in terms of weight saving and insulation. This paper presents pre-research for evaluating and predicting the pumpability of LWAC, which includes a test method developed for determining the pressurized absorption characteristics of LWAs. The test equipment needed for this consists of a pressure vessel combined with a plug to approximate a pump piston and provide pressurization by means of a loading device. A displacement meter is also included to measure the range of plug movement during pressurization. The testing procedure consists of six steps: adjustment of water levels, aggregate input, greasing, alignment, deaeration within the vessel, and finally pressurization with measurement. Equations to estimate porosity and provide a reference load-displacement curve are derived from the results of testing hollow spheres, and then applied to determining the absorbed void volume ratio of aggregate under pressure from the displacement of the plug. The pressurized absorptive characteristics of LWAs are also estimated by comparing the slope of their load-displacement curve to the reference curve. This reveals that the displacement of LWAC is highly dependent on the displacement of the LWA it contains.KeywordsLightweight aggregateLigthweight aggregate concretePressurized absorptionPumpability