Study on the Properties of SCLAC Using Infrared Thermography and Ultrasonic Pulse Velocity

Abstract

Abstract A densified mixture design algorithm (DMDA) was employed to produce self-consolidating lightweight aggregate concrete (SCLAC). Lightweight aggregates with different particle densities were evaluated, and the batched water density and water-to-binder (w/b) ratio were varied. The results indicated that the properties of SCLAC mixed according to the DMDA were better than those according to the American Concrete Institute (ACI). Specifically, the slump and slump flow were greater than 250 mm and 500 mm, respectively. For instance, the strength of the material developed quicker; after 7 days of aging, the compressive strength of the specimen was 72 % of the strength obtained after 28 days. Under identical conditions, the compressive strength of SCLAC showed the best development when the w/b ratio was equal to 0.32 (45 MPa after 91 days). When the lightweight aggregate concrete was mixed according to the ACI mixture’s algorithm, the electrical resistivity of the SCLAC reached 53 KΩ-cm and improved to 40 KΩ-cm. The durability of material synthesized according to the DMDA was better than that of the traditional ACI mixture design. The degree of aggregate floating affected the location of the particles and the uniformity of concrete by approximately 20–40 %. Moreover, the results revealed that a low w/b ratio or mixing water density enhanced the development of the pulse ultrasonic velocity. The ability of aggregates with different specific gravities to transmit heat was determined by applying an infrared thermal method, and the results suggested that specimens with different particle densities (800 and 1,300 kg/m3) presented significant differences in temperature variations. Lastly, scanning electron microscopy showed that hydration continued as the age of the material increased, which increased the compressive strength and compactness. In conclusion, a concrete mix designed with DMDA has higher workability and reaches design strength faster.