Roller compacted concrete (RCC) has gained acceptance as a paving material due to its strength, economy and fast placement. In this paper, variation in aggregate type and influence of GGBS on drying shrinkage properties of RCC was explored. The experimental results indicate that crushed gravel aggregates presents higher shrinkage strain as compared to limestone. Also, the shrinkage strain of RCC increased with the increase in replacement level of cement with GGBS. Further, a multivariable regression model is developed for shrinkage strain prediction of RCC, considering the effect of aggregate type and percentage incorporation of GGBS on the shrinkage behaviour. The obtained higher correlation coefficient indicates that the developed model can be effectively used to predict the shrinkage strain of RCC.
Roller compacted concrete
Drying shrinkage strain
Multi regression model
Roller compacted concrete (RCC) is a dry concrete that exhibits zero slump and gained popularity because of economy, strength and fast placement [1,2). RCC has gained acceptance as a pavement material because it does not require formwork, reinforcing steel and dowel bars, and thus economizes the overall construction cost of the pavement. The cost saving of upto 60% can be achieved by using RCC pavements as compared to the conventional concrete pavements [3,4]. The basic ingredients of the RCC are similar with the conventional concrete although the proportioning of these ingredients varies. RCC requires larger proportion of sand, lesser water and lower cement content on comparison with the conventional concrete. Previous studies show that RCC is a strong and durable material for pavements, with strength even greater than the conventional concrete pavements [4-7]. Since the RCC mixes are widely used in pavements so drying shrinkage becomes an essential parameter for its acceptability.
Drying shrinkage is defined as the volumetric shrinkage of concrete, because of loss of moisture during drying with time . This volumetric change introduces tensile stress in concrete ultimately leading to cracking of RCC pavements. Shrinkage cracks adversely affect the pavement surface with decrease in durability and increase in roughness of pavements. Pittman and Ragan  reported that the grading of aggregates and the moisture content of the mix has great influence on drying shrinkage of RCC. It was reported that coarse aggregates characteristics such as quantity, type, surface texture, moisture content as well as supplementary cementitious materials play an important role in controlling shrinkage behaviour of conventional concrete [8,10-12].
Till date, extensive research which accounts the effect of coarse aggregates characteristics on shrinkage behaviour was focused on the conventional concrete [11-14]. For instance, Al-Attar T.S.  reported that limestone aggregates present lesser shrinkage strain than the uncrushed gravels. Fujiwara T.  also observed that the shrinkage strain of concrete reduces by using light weight aggregates. Zhang et al.  found that drying shrinkage of concrete is influenced by the material characteristics of the aggregates, which includes the specific surface area, water absorption ratio, aggregate shrinkage strain and the pore structure of aggregates. In order to reduce the drying shrinkage of conventional concrete,...