Materials and Structures/Materiaux et Constructions, Vol. 33, June 2000, pp 338-344 Utility of statistical models in proportioning self- consolidating concrete K. H. Khayat, A. Ghezal and M. S. Hadriche Universit~ de Sherbrooke, Sherbrooke, QC, Canada Paper received:July Ist, 1999; Paper accepted: September 20, 1999 A B S T R A C.T R I~ S U M I~ In addition to sound material selection, the mix design of self-consolidating concrete requires careful tailoring of mixture constituents to secure a proper balance between contradictory properties necessary for the successful pro- duction of such a complex material. Mixture optimization of self-consolidating concrete often requires several trial batches to secure the required characteristics. This paper reviews statistical models developed using a factorial design approach to understand the effect of mixture parameters on key responses, including slump flow, theological para- meters, filling capacity, V-funnel flow time, surface settle- ment, and compressive strength. The models are valid for mixtures with 0.37 to 0.50 W/CM, 360 to 600 kg/m3 of binder, 240 to 4001/m 3 of coarse aggregate, 0.05 to 0.20% of viscosity-enhancing agent, by mass of water, and 0.3 to 1.1% of high-range water reducer, by mass of binder. Although the predicted response changes with the deviation from material characteristics used in establishing the models, the models remain quite useful in &terming the significance of mixture parameters and their interac- tions on self-consolidating concrete properties. This paper demonstrates the usefulness of the models in establishing trade-offs among mixture parameters necessary for mix- ture optimization and compares the effect of changes in such parameters on key self consolidating concrete responses. The utility of the models to establish correla- tion between different workability characteristics useful for quality control is also highlighted. La formulation des b~tons autoplacants n&essite une attention particuli&re clans la s&ction des constituants afin d'assurer un ~quilibre entre les propri~t& contradictoires et n&essaires a l'obten- tion de ce mat&iau. L'optimisation des m&nges des b~tons auto- plafants exige plusieurs gdch&s d'essais pour garantir toutes les propri~t~s requises. Ce travail passe en revue les modules statis- tiques d&elopp& par l'approche des plans factoriels pour com- prendre l'effet des facteurs sur les @onses recherch&s, a savoir : l'&alement, les paramdtres rh&Iogiques, ta capacit~ de remplis- sage, l'entonnoir, le tassement et la r&istance a la compression. Les modules propos& sont valables pour un rapport ElL compris entre 0,37 et 0,50, une teneur en liant de 360 a 600 kg/m 3, un volume en granulats variant entre 240 et 400 l/m 3, un dosage en agent d'am~lioration de la viscosit~ compris entre 0,05 et 0,20% de la masse totale en eau et un dosage en superplastifiant variant entre 0,3 et 1,1% de la masse totale du liant. N&nmoins, les r~ponses pr~dites changent en s'dloignant des caract&istiques des mat&iaux employ& pour l'~laboration des modules, l'int&~t des modules est prouv~ en d3montrant l' effet des param&tres de m~langes et burs interactions sur les propri~t& des b~tons autoplafants. Ce travail tente de d~montrer l'utilitd des modules pour I'~tablissement d'un consensus entre les diff&ents param~tres et une optimisation des m~langes ainsi que de compa- rer l'effet du changement des param~tres de m~langes sur les i t . ! ,. i a reponses. Le present article &cute egalement I mteret des modules en vue de trouver des correlations entre les caract&istiques de maniabilit~ en mati~re de contrale de qualitY. 1. WORKABILITY OF SCC Self-compacting concrete (SCC) is a special type of concrete that should flow into place and around obstruc- tions under its own weight without segregation and flow blockage and with no significant separation of material constituents thereafter until the setting. The successful casting of SCC necessitates that the concrete exhibits a certain balance between deformability and stability. A SCC is typically characterized by a low yield value to ensure high deformability and a moderate viscosity to secure sufficient stability and filling of the formwork. The mixture proportioning of SCC is complex and involves the tailoring of several variables to strike a bal- ance between the workability requirements affecting the sucessful casting of SCC. Flowability through restricted Editorial Note Prof. Dr. Kamal Khayat is a RILEM Staff Member. He participes in RILEM TCs 145-WSM (Workability of Special concreteMixes) and 174-SCC (Self-Compacting Concrete). 1359-5997/00 @RILEM 338