Resource-efficient design of ultra-high performance concretes

This research introduced and implemented the resource-efficiency factor (R) for the development of non-proprietary UHPC considering relative workability, compressive strength, cost, and carbon footprint (CFP) of the UHPC matrix. The effect of each of these four parameters of material performance is linked with the structural performance of a reinforced beam, a short column and a closure pour connection. The process of resource-efficient design has been exemplified by the development of non-proprietary UHPC using suitable materials available in the New England area in the United States. At first, different locally available materials and their combinations were selected to design 30 UHPC matrices at same proportion. Then the R-factor was used to evaluate their resource-efficiency leading to an optimized matrix with R-factor of 1.36. Afterwards, optimizing the aggregate to cement (A/C) ratio resulted in an R-factor of 2 which is 67 % higher than that of most non-proprietary UHPC matrices in the US. In the next step, an optimized matrix was used to design UHPCs with different A/C ratios and one type of steel fiber reinforcement of volume fractions of 1 %, 1.5 % and 2 %. The results were compared to commercially available UHPC mixtures and non-proprietary UHPC mixtures in the US. In addition, the optimized UHPC matrix was further optimized by proportioning the amount of silica fume and ground granulated blast furnace slag which increased the R-factor by 6 %. Overall, this research showed that UHPC can be successfully designed using the R-factor methodology. Compressive strength of 156 MPa-233 MPa were achieved without the use of special treatment at current material cost and CFP of about US$500/m3 and 500 kg/m3 without fibers, and in between US$700 to US$1100/m3 and 800 kg/m3 with fibers available in the US.