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Methods previously developed to predict the performance of AM2 aluminum airfield matting subjected to single-wheel aircraft loads were evaluated in this paper to determine their validity for the complex six-wheel Boeing C-17 main landing gear. These methods, derived from full-scale accelerated Boeing F-15E trafficking, were used to predict deformation of the subgrade as a function of the California bearing ratio (CBR) and the number of aircraft passes. The same data set was also used to predict fatigue failure of the mat system's joints over any CBR. A laboratory test fixture and procedure were designed to mimic the boundary conditions experienced by the mat during full-scale experiments (single-wheel F-15E in the original experiments) so that variations of the joints and any subgrade CBR can theoretically be tested in fatigue without the expense of full-scale experiments. Results presented in this paper showed that, even with a more complex loading configuration (i.e., C-17), the trends published previously for the F-15E were supported, and the procedures offered reasonable predictions for AM2. [ABSTRACT FROM AUTHOR]

Aggressive use of supplementary cementitious materials (SCMs) in concrete is becoming more appealing due to potential for cost effectiveness, reduced environmental impact, enhanced durability, and increased sustainability. Constructability, though, is often less attractive as time of set and early strength development can be delayed. This paper investigated the merits of incorporating portland-limestone cement (PLC) to improve concrete sustainability and performance when rounded gravel aggregates (most sustainable for some markets) were used in conjunction with dual SCMs proportioned for 50 % to 70 % total cement replacement. The family of concrete mixtures evaluated have not been widely studied with PLC (in the US or elsewhere). Mixtures containing PLC designed for improved synergies in the US construction market were compared to similar variations containing ordinary portland cement (OPC). PLC was shown to be able to produce concrete mixtures of greater compressive strength and lower set times compared to OPC in some, but not all, conditions. Individual mixture performance varied based on SCM use, PLC properties, and aggregate properties. [ABSTRACT FROM AUTHOR]