Reactive Powder Concrete (RPC) is a newly emerging concrete material that is being used for various applications where high-strength concrete is required. RPC is obtained by removing coarse aggregates and adding fine powders such as silica fume into the concrete mixture. This research has focused on the proportioning and characterization of RPC mixture to be used as a material for energy storage pile application. For mixture parameters, the water-to-binder ratio (WB), silica fume (SF) content, and normal and warm temperature curing have been selected. The relative flowability, penetration resistance, setting time, drying shrinkage, and compressive and flexural strengths were evaluated. Based on the test results, the mixture with WB = 0.22 and SF = 20% was the best mixture with the highest tensile strength and other characteristics. Response surface methodology (RSM) was used to design the experiments and find the optimum mixture proportions to achieve the highest compressive strength. The optimum WB and SF content to achieve the highest strength for combined ages (7 days, 28 days, and 56 days) was determined to be WB = 0.213 and SF = 20%. Through the comparison between the test results and the required strength from analytical simulations, the RPC studied in this paper was deemed to be suitable for the energy storage pile.

This research investigates the effects of aggregate packing degree on the strength of Reactive Powder Concrete (RPC) mixtures on the basis of the Toufar model. To optimize the packing degree of sand for strength development of RPC, various sand blends with the combination of different fraction size were used. In addition, 10 different blends that showed best packing degree were chosen to investigate the compressive strength of RPC. It was found that experimental verification results conform to Toufar model calculations. The test result shows that packing degree had a significant effect on the strength of RPC: Mixtures with higher packing degree can achieve higher compressive strength. Furthermore, Results indicate the Toufar model can predict packing degree of aggregate blends.

A new reinforced concrete foundation system is being proposed to store renewable energy through the compressed air energy storage technology. For this application, the concrete is required to resist considerable tensile strength and to have low air permeability, which is not observed in normal concrete. Therefore, this paper is proposing to use reactive powder concrete for the suggested foundation system. Reactive powder concrete (RPC) is obtained by introducing either micro-cementitious materials like silica fume or fine powders like crushed quartz into the concrete mixture from where coarse aggregates had been removed. RPC has low water content and dense particle packing which lead to high strength and low air permeability characteristics. This paper conducts preliminary experimental investigations on the strength and air permeability of the RPC. Two important mix design parameters are studied including water-to-binder ratio ad silica fume content. Preliminary correlations between mix design parameters and strength/air permeability are developed. From the preliminary test results, it is concluded that the reactive powder concrete has potential to meet the high strength and low air permeability requirements, and is suitable for the proposed energy storage foundation system.

The main goal of this study was to optimize the compressive strength of reactive powder concrete (RPC) for an energy storage pile application using response surface method (RSM). The compressive strength of 9 different RPC mixtures along with 3 plain concrete mixtures was determined. Silica fume (SF) content and the water-to-binder ratio (w/b) were selected as parameters to influence the compressive strength of the concrete mixture. RSM regression analysis was used to develop a prediction model of compressive strength. Based on test results and linear interpolation, the combination of 20.46% SF and w/b=0.20 was determined to achieve the highest compressive strength.

This paper is the study of sulfate attack resistance of reactive powder concrete (RPC). RPC that is also known as ultra-high performance concrete is a special type of concrete material obtained when fine powders like silica fume (SF) are added into the concrete mortar along with very low waterto-binder ratio (w/b). SF is a pozzolanic material obtained as a by-product of silicon metal or ferrosilicon alloys production. In this study, total 6 different RPC mixtures with various w/b (0.18, 0.22 and 0.26) and various SF content were studied. SF was added into the concrete mixtures in the amount of 15%, 20% and 25% of cement by weight. The other testing parameter includes 3 different concentrations of sodium sulfate (Na2SO4) solutions (0.35 M, 0.7 M and 1.4 M concentrations). Broad laboratory investigations of behavior of the RPC mixtures were conducted in terms of compressive strength and mass gain of cubes (50×50×50 mm 3) and expansion and mass change as in accordance with ASTM C1012. Test results had been analyzed and assessed by Taguchi method. The significance level of experimental parameters was determined by using Analysis of variance (ANOVA) method. According to statistical and analytical results it was observed that RPC has high sulfate attack resistance. Moreover, addition of optimal amount of SF into the RPC mixtures as well as decreasing w/b can significantly improve Na2SO4 resistance of RPC.