Measuring Shrinkage of Self-Consolidating Concrete Incorporating Fly Ash and Silica Fume Using Fiber-Optic Sensor

Abstract

This paper presents a long-term concrete shrinkage test on self-consolidating concrete (SCC) conducted at The University of Hong Kong. In this study, one normal concrete mixture with only portland cement and five SCC mixtures incorporating fly ash or both fly ash and silica fume were produced and tested for their shrinkage characteristics in the form of prismatic specimens. Fiber-optic sensors, which give stable and reliable measurements, were embedded into the prismatic concrete specimens to measure shrinkage strains. Compared with the normal concrete mixture, the autogenous shrinkage of the SCC mixtures included in this study is larger while the one-year drying shrinkage is smaller. Besides, lowering the water/cementitious materials ratio of a SCC mixture would increase its autogenous shrinkage but reduce its one-year shrinkage. Experimental results also reveal that replacement of cement by fly ash would reduce both autogenous and one-year shrinkage strains of SCC whereas replacement of cement by silica fume would increase both. Lastly, the shrinkage half-time of SCC is found to be longer than that of the normal concrete.