Experimental determination of creep coefficients for sintered flyash lightweight aggregate based concrete and verification with creep models

Abstract

The experimental creep coefficient has been determined for two concrete strengths of about 40 MPa and 60 MPa using sintered flyash lightweight aggregate and granite aggregate in creep rig with capacity of 1500kN as per ASTM C-512. The creep results indicate that despite both density and modulus of elasticity being on lower side for sintered flyash lightweight based concrete, the creep coefficient has been lower than that of normal weight concrete with granite aggregate for same strength level. The comparison of existing creep models has been carried out with experimental results for both normal and lightweight concrete considering parameters in models such as relative humidity level, concrete mix ingredients, aggregate properties, oven dry density, elastic modulus of both concrete types etc. considered in study. The creep coefficients have been obtained experimentally at loading age of 28-day and testing period of 365 days and has been compared with existing creep models such as B-3, B-4, ACI-209, EN:1992/FIB. For the similar compressive strength level, creep coefficient of structural grade lightweight concrete is found to be lower in comparison to creep coefficient of normal weight concrete as the internally stored water in porous aggregates keeps capillary pores almost saturated and leaves minimal chance for seepage to occur.