K. NAGENDRA PRASAD (1), M.L. NARASIMHULU (2) and R. MANOHARA REDDY (3)
(1) Professor of Civil Engineering, College of Engineering,
Sri Venkateswara University,Tirupati, 507512, India
(2) Associate Professor in Civil Engineering Department,
G. Pulla Reddy Engineering College, Kurnool-518 002 (A.P), India
(3) Superintending Engineer, APMSIDC, Kadapa, AP, India
Extensive use of compressed blocks in various fields of engineering has become a reality. In this investigation, an attempt has been made to advance a simple phenomenological model for the rapid calculation of different combinations of ingredients, to satisfy the requirements of strength development with age with minimum laboratory trials. The underlying basic framework is Abrams’ law, which is extensively used in concrete technology. In this investigation, use of 75 percent sand and 25 percent rock dust resulted in optimal density of aggregate constituents, with minimum but sufficient voids left for cement and fly ash paste during compaction. Since the quantity of cementing materials used is low, the workable water : cementing materials ratio has been kept in the range of 0.7 to 0.9. While the bulk density is reduced with reduction in water : cement ratio, the strength mobilized with age also got reduced. Keeping the bulk density constant, by use of additional mix material and compaction effort can avert this. In such a case, the strength development follows Abrams’ Law. It has been possible to generalize Abrams’ Law by normalizing strength values at water : cementing materials ratio, S0.8, as a reference value for the development of the phenomenological equation. This generalized approach, to predict the strength has been validated by independent experimental data generated for this purpose.