Materials' and Structures / Matdriaux et Constructions, Vol. 37, October 2004, pp 513-521 Rheology of high flowing mortar and concrete M. A. Noor 1 and T. Uomoto 2 (1) Department of Civil Engineering, The University of Tokyo, Japan (2) Center for Collaborative Research, The University of Tokyo, Japan ABSTRACT Rheology of high flow mortar and concrete was studied using coaxial cylinder rheometer and lifting sphere viscometer. The tests results were compared with the traditional test methods of high flowing mortar and concrete. Generalized equations for viscosity and yield stress of the mortar and concrete were then developed based on this investigation. The Fan'is model was used to calculate the viscosity and a new model was proposed to calculate the yield stress for the generalized equations. These models were validated using test results of different high flow mortar and concrete. The study also revealed that the rheology values obtained using the coaxial cylinder rheometer and lifting sphere viscometer test are significantly different. RESUME La rhOologie de mortiers et bOtons ayant un Ocoulement OlevO a OtO Otudide h l'aide d'un rhOomOtre gl cylindre coaxial et d'un viscosimbtre soulevant une sphOre. Les rOsultats des essais ont OtO comparOs aux mOthodes d'essai traditionnelles des mortiers et bOtons h Ocoulement OlevO. Les Oquations gOnOralis~es pour la viscositO et la contrainte d'Ocoulement des mortiers et bOtons ont OtO dOveloppOes h partir de cette investigation. Le modble de Farris a OtO utilisO pour calculer la viscositO et un nouveau modOle a OtO proposO pour calculer la contrainte d'Ocoulement dans les ~quations gOn~ralisOes. Ces modules ont ~t~ valid~s au moyen des rOsultats des essais portant sur diffOrents mortiers et bOtons ayant un Ocoulement ~levO. L 'Otude a aussi rdvOlOque les valeurs rhOologiques obtenues en utilisant le rhdom~tre h cylindre coaxial et lors de l'essai du viscosimbtre soulevant une sphbre sont consid~rablement diffOrentes. 1. INTRODUCTION High flowable concrete (HFC) is used in highly congested reinforced areas since it can flow easily by its own weight. The HFC has high slump flow and self-leveling capacity in U-box test without reinforcement. A detailed rheology study of the HFC is important to understand the behavior of the concrete. However, no significant attention was paid on this subject until this date. In this research, slump flow test, V-funnel test and rheometer test have been performed on both mortar and concrete to observe their relations with rheology of mortar and concrete. Both coaxial cylinder rheometer and lifting sphere viscometer tests were used to determine the rheology of the materials. Rheometer test results were compared with the traditional test methods of HFC. Mixture proportions were varied to examine the effect of the mixture proportion on the rheology values. The mortar was separately mixed without any wet screening. It was reasonably assumed that the properties of this mortar would be the same as those when it was in the concrete. The study was extended to develop generalized equations of rheology using those mix proportions. The mortar and concrete were assumed to behave as a Bingham fluid. 2. MATERIALS USED The materials used in this study were readily available on the Japanese market. In this research Ordinary Portland Cement (OPC), Ground Granulated Blast Furnace Slag (GGBS), Sand, Gravel and Superplasticizer were used. OPC complying with JIS A 6206 was used. The specific gravity was 3.16. The Bogue equations [1] were used to estimate the theoretical compound composition of OPC, from the chemical composition, which is given in Table 1. In this study, only GGBS, complying with JIS A6206, was used as cement replacement material. A superplasticizer, high range water reducer type, was used for all mixes. The specific gravity of the admixture was 1.05. 1359-5997/04 9 RILEM 513