Using mixture design method for developing and optimizing eco-friendly ultra-high performance concrete characteristics

Due to its high cement content, ultra-high performance concrete (UHPC) is not an eco-friendly material. Utilizing alternative materials as a replacement of cement could improve UHPC's sustainability and reduce environmental impact. This study intends to examine the impact of using different alternative filler materials such as quartz powder (QP), limestone powder (LP), granite powder (GP) and basalt powder (BP) along with silica fume (SF) as a cement replacement on mechanical characteristics and durability of UHPC. The total powder content composed of 60% cement, 20% SF, and 20% filler materials (QP, LP, GP, and BP). Mixture design method in Minitab program was used to design concrete mixtures. Flowability, compressive strength, water permeability, rapid chloride permeability, sulfate resistance and concrete microstructure were the tests performed on the concrete mixtures. Utilizing QP, LP, BP, and GP as a partial replacement of cement in the production of UHPC resulted in significant negative impact on concrete flowability. UHPC with low environmental impact and compressive strength more than 120 MPa with higher durability could be produced using QP, LP, BP, and GP as a replacement of cement. Mixture composed of 711 kg/m3 cement, 237 kg/m3 SF, 118.5 kg/m3 QP, 118.5 kg/m3 BP, 1017 kg/m3 sand, 142.2 kg/m3 water, 31.3 kg/m3 super plasticizer, and 156 kg/m3 steel fibers achieved the highest compressive strength at age 7, 90, 180 days, the strength were 85 MPa, 123 MPa, and 126.1 MPa respectively. The findings demonstrated the development of a strong relationship between responses and constituent materials in predicting and optimizing compressive strength of UHPC, enabling construction implementers to obtain mixture design proportion to obtain UHPC with certain desirable properties using the proposed models without resorting to making experimental mixtures using a trial-and-error method, which consume time and effort.