Exploring engineering properties of sustainable multi‐grade concrete: Materials, structural, and environmental aspects

Abstract

Through experimental and theoretical studies, this research explores the materials, structural, and environmental aspects of multi‐grade concrete (MGC), a potentially sustainable structural concrete. The experimental part investigates the compressive, split cylinder, flexural, and shear strengths of MGC, essential parameters for the design of structural members composed of MGC. It also provides the relationships between various strengths. The compressive behavior is correlated with the cracking pattern and the confinement effect caused by the end platens. The theoretical study involves determining the carbon emissions (CEs) and modifying ASTM/ACI expressions for the flexural tensile strength (FTS) and shear capacity applicable to MGC. Three uni‐grade concretes (UGCs) with distinct materials, properties, and grades: grade 17 (G17), grade 25 (G25), and grade 30 (G30), were poured in layers of varied thicknesses to make two variants of MGC. Experimental investigations showed that the higher‐strength concrete (HSC) confined the lower‐strength concrete (LSC) part thus increasing the compressive strength. Replacing 50% of LSC with HSC led to an increase in compressive and shear strengths by 21% and 40%, respectively. The shear strength values of reinforced MGC beams observed experimentally are aligned with those obtained through the modified expressions developed by the authors. A trade‐off analysis among the strengths, CEs, and costs of UGC and MGC can aid in selecting MGC customized to specific requirements, thereby contributing to the development of sustainable structural concrete.