Optimization of the Composition of a High-Performance Concrete

Abstract The production of a high-performance concrete (HPC) is more of an art than a science, although the basic principle needed to be implemented is simple: HPC is a concrete having a low waterbinder ratio (W-B). Achieving a low water-binder ratio can be realized in many different ways. The work reported hereafter tries to answer three basic questions: • Is it better to use the least amount possible of mixing water with a high dosage of superplasticizer to obtain the desired workability, or is it better to use more water (and more cement), but less superplasticizer? • Is the use of silica fume advantageous in making HPC? • If yes, what is the maximum price that can be paid for it? A factorial design plan involving 18 laboratory concrete batches has shown that the use of silica fume is advantageous up to a price of $600/ton (CAN) (for the conditions of the experiment). Moreover, it was found that for a precast operation, it is better to increase the amount of water used in making HPC and to decrease the amount of superplasticizer; for the ready mix operation, the reverse is true. Silica fume and the superplasticizer employed were shown to be effective fluidifying agents, although they did slightly increase the time at which maximum compressive strengths were reached. Erratum to this paper appears in 17(1).