Mechanical and fresh properties of high-strength self-compacting concrete containing class C fly ash

Abstract

In the present study, using the locally available materials in Christchurch, New Zealand, a commercially reproducible high-strength self-compacting concrete (HSSCC) mix of 100MPa compressive strength was designed following the available guidelines for normal-strength self-compacting concrete (NSSCC). Benchmark mixes of conventionally vibrated high-strength concrete (CVHSC) were also designed considering the most important parameters in producing comparable concrete mixes; i.e. similar water-to-binder (w/b) ratio and comparable concrete compressive strength. It was found that with an equivalent w/b ratio, HSSCC develops considerably higher compressive strength (more than 15MPa) compared to that of CVHSC. Therefore, a lower w/b ratio was chosen to reproduce CVHSC mix with strength comparable to the HSSCC mix.Fresh properties (slump cone, slump flow, J-ring, L-box and V-funnel) and mechanical properties (compressive, splitting tensile and flexural strengths as well as modulus of elasticity and shrinkage) of all concrete types were evaluated at 3, 7, 28, and 90days. The microstructure of the mixes was assessed by means of resistivity, porosity and SEM imaging. New expressions were developed to predict different characteristics of HSSCC and suggestions were made to modify the existing equations where applicable. Finally, experimental results of this study were compared with some of the available codal provisions in order to assess the applicability of the existing criterion to HSSCC.