A critical review of proportioning techniques for self-compacting concrete
Paper i proceeding, 2009
This paper presents a critical review of proportioning techniques for self-compacting concrete (SCC). Conventional proportioning techniques used in the production of concrete are to a great extent empirically or semi-empirically based on some old rules such as Fuller’s curve (1907) and Abrams’ rule (1918) for normal concrete, and with certain modifications by adding various fillers and using superplasticizer for SCC. Due to the limited resources of natural aggregates in Sweden as well as in the other countries, crushed aggregates have to be used in concrete production in the future. The previous experience based on natural aggregates can in many cases not be applied to the production of SCC, which is very sensitive to the particle size distributions, shapes and surface characteristics of various raw materials. It is a great waste of natural and human resources to establish new experience for every locally available crushed aggregate if the conventional experience-based proportioning techniques by “trial and error” are used for the production of SCC. In this paper a new approach is proposed by taking into account the grain shape of angular aggregate in the particle grading and the flow coefficient of aggregate in the calculation of paste volume for spacing aggregate particles. The BET specific area of fine materials is used for calculating the need of additional water for lubrication of fine particles. The results from some trial mixes show that the new approach is more effective in reaching reasonable good mixture proportions when compared with simple “trial-and-error” methods.