Abstract:
This research presents a part of an ongoing experimental laboratory investigation being carried out for production and characterization of High Strength Concrete (HSC) for the Dam Complex of Upper Atbara Project concrete dam which is located in the East of Sudan. The main objectives of this research are to produce concrete with compressive strength of 85 MPa using local available ingredients, to study the effects of different proportions of Silica Fume and various combinations of Silica Fume and Fly Ash on the mix and to find the optimum range of Silica Fume and Fly Ash contents.
Hundreds of specimens were performed and tested using local aggregates with addition of supplementary cementitious materials (Silica Fume, Fly Ash and Super Plasticizers). The Silica Fume and Fly Ash were added by weight of cement as a replacement. Various percentages of Silica Fume (SF) and Fly Ash (FA) were added at different Water/Cementitious materials Ratios (W/Cm). Twenty two mix design trials of grade 85 MPa had been successfully produced and their mechanical properties were measured and documented. The compressive strength tests were carried out on concrete specimens (cubes) at 7 days and 28 days, also the fresh concrete tests (Slump Test and Flow Test) have been done. A statistical approach was followed during the analysis of the test results according to ACI 211.4 and using Microsoft Office Excel program.
The analysis of the test results has shown the target compressive strength of 85 MPa was achieved with a range of Course Aggregate to Fine Aggregate ratio of (1.4 to 1.9), Optimum Water/Cementitious materials ratio of (0.25), the Super Plasticizer-binder ratio was set to be (1.6%), Silica Fume dosage was fixed to (8%) and finally the Fly Ash dosage was (12%). Test results were found to support the reviewed information on HSC production from local available aggregates in Sudan. Also the water/ Cementitious materials ratio and the suitable admixtures with their optimum dosages were found to be the most important parameters for producing HSC.
