Mechanical Property Prediction for High Early Strength Self-Consolidating Concrete

Abstract

Concrete design codes include equations to estimate the modulus of rupture (MOR), modulus of elasticity (MOE), and splitting tensile strength (STS) of concrete based on the compressive strength. These equations have been developed based on data from normal strength conventional concrete (CC). Precast/prestressed concrete plants require that the concrete used to fabricate their structural members attain high early strength (HES). Plant conditions lend themselves to the use of self-consolidating concrete (SCC) and HES SCC could be an economical option for use under these conditions. However, limited work has been documented to determine if SCC can achieve high early strengths and limited work has been reported to determine if standard design equations are applicable for HES SCC. SCC is proportioned to achieve good flow while maintaining a homogeneous structure. To achieve this, SCC typically has to have higher paste and lower coarse aggregate volumes than CC. These conditions and the addition of newer chemical admixtures and supplementary cementitious materials (SCMs) could result in the mechanical properties of the SCC being different from those of CC. This research investigated the correlations between the compressive strength and the MOE, MOR, and STS. Results indicate that existing equations in the American Concrete Institute (ACI) and the AASHTO load and resistance factor design specifications can be used to estimate the MOE and STS of HES SCC. However, the applicability of AASHTO lower and upper bound MOR expressions depends on the influence of the compressive strength on measured to predicted MOR values. AASHTO lower and upper bound MOR expressions are considered appropriate design equations for SCC mixtures with measured compressive strengths ranging from 55 to 76 MPa (8 to 11 ksi). Equations developed in this research can be used for similar HES SCC mixtures with compressive strengths ranging from approximately 34 to 110 MPa (5 to 16 ksi).