Papers by Keyword: Reactive Powder Concrete (RPC)

Abstract: Aim & Goff model was used to predict the packing density of cementitious material including cement, ultra-pulverized fly ash and silica fume. The mix proportions of reactive powder concrete (RPC) with different packing density and calcium-silicon ratio of cementitious material were designed, and a strength test was carried out. The study results reveal that the flexural strength and compressive strength of RPC are related to the packing density and calcium-silicon ratio of cementitious material. For the mix proportion of RPC with the calcium-silicon ratio of 1.179, calcium hydroxide reacts with silicon dioxide fully, and the superfluous ultra-pulverized fly ash and silica fume fill the voids of RPC. The packing density of its cementitious material is the largest, and its strength approaches summit.

Abstract: After modification, Toufar model was used to calculate the packing degrees of sand mixtures with different particle sizes. For four gradations of sands, the weight ratios of different types of sands with different size ranges, which achieve maximum packing degrees, have been obtained using the modified Toufar model. A strength test of reactive powder concretes (RPCs) with the four gradations of sands was reported. The test results show that the strength of RPC is related to both the maximum grain size and the packing degree of sand mixture. The smaller maximum grain size and larger packing degree of sand mixture can achieve the higher strength of RPC.

Abstract: In ordinary processing condition, using small amount (2%) of polymer to modify reactive powder concrete (RPC), the performance of modified and unmodified RPC was studied for their corrosion resistance with water-dip-in, acid-dip-in and sulphate solution-dip-in tests and was verified by the strength loss rate. The results show that not only the corrosion resistance but also the strength, especially the flexural strength, has been improved obviously after the polymer modification. The mechanism has been studied with SEM and EDS analysis.

Abstract: This paper presents a review of advances in research on fire resistance of high-strength concrete (HSC) and ultra-high-strength concrete (UHSC). Further research needs in the near future on UHSC, especially on reactive powder concrete (RPC), are also discussed. It is commonly recognized that HSC suffers strength loss in a manner basically similar to that of normal strength concrete. But the main problem of HSC is explosive spalling under high temperature, which can be solved by employing either polymer fiber or steel fiber. Since RPC200 is a type of RPC which has been successfully prepared in many counties and is to be applied to engineering practice, fire resistance of RPC200 needs a series of investigations urgently. The objectives of such investigations are to restrain explosive spalling and minimizing spalling probability, so as to ensure satisfactory fire resistance of RPC. It is expected that a research will be carried out on explosive spalling behavior, fracture properties, and micro-structure, to establish a mechanism as well as technical measures for improving fire resistance of RPC.

Abstract: By means of the three-point bending impact equipment, with the measurement of ultrasonic velocity, the low velocity impact damage evolution of reactive powder concrete (RPC) with 0, 1%, 2% and 3% volume fraction of steel fiber were tested. In this study, the damage variable D pertaining to ultrasonic velocity had been selected to study the damage evolution process of RPC. The results indicate that the fatigue damage process of RPC is linear. The addition of fibers effectively improves the impact energy absorption behavior of RPC matrix, and the damage variable D of RPC with different fiber dosages increases by 1.1~3.5 times than that of plain concrete when it is ultimately destroyed.

Abstract: Reactive powder concrete (RPC) is one of new composite material, which is applied in the pilot project of the railways construction. According to the literature survey and test data report, the major factors which influence the reliability of 32m prestressed RPC girder in railway bridges are given in this paper. Furthermore, combining numerical simulation with finite-element method, the reliability of the prestressed RPC girder is calculated. The results show that the failure probability and reliability parameter can be obtained through direct sampling method and the latin hypercubic sampling method. The reliability parameter of fracture is 3.9 with two methods, while the reliability parameter of deflection control is 4.1 and 4.2 respectively with the two methods, and the reliability parameters meet the demands of norm of railway bridges. Consequently, the RPC is safety to be used in the railway bridges.

Abstract: Reactive Powder Concrete (RPC) is a kind of cement-based composite which has ultra-high strength, high ductility and durability. RPC has great fragility, bad ductility and bursting fragility destruction subjected to high or complicated stress. The fragility performance of RPC will be improved when RPC is cast in steel tubes. The behavior of axially loaded RPC-filled steel tube circular stub columns is presented in this discussion according to the experiment and finite element analysis. An accurate finite element model was developed to carry out the analysis. Accurate nonlinear material models for confined concrete and steel tubes were used. The results obtained from the finite element analysis were verified against experimental results.

Abstract: Aim & Goff model was used to predict the packing degree of cementitious materials including cement and silica fume. The mix proportions of reactive powder concrete (RPC) with different packing degree and calcium-silicon ratio of cementitious materials were designed and a strength test was carried out. The study results reveal that the flexural strength and compressive strength of RPC are related to the packing degree and calcium-silicon ratio of cementitious materials. For the mix proportion of RPC with the calcium- silicon molar ratio of 1.353 that is slightly less than the theoretical value of 1.42, where calcium hydroxide can react with silicon dioxide more fully, its strength of RPC approaches summit although its packing degree of cementitious material is not the largest one.

Abstract: Based on orthogonal array testing strategy (OATS), the effects of sand-binder ratio (S/B), water-binder ratio (W/B), and the ratio of steel fiber volume to reactive powder concrete (RPC) volume (STF/R) on the compressive strength and chloride diffusion coefficient of RPC were investigated using an artificial neural network method. Research results reveal that the compressive strength of RPC approaches summit when STF/R is 2% or W/B is 0.18-0.2%, and decreases with the increasing of S/B. Furthermore, the chloride diffusion coefficient increases with W/B or STF/R and decreases with S/B.

Abstract: Reactive Powder Concrete (RPC) is a new kind of engineering material with high strength, high elastic modulus and high durability. In order to satisfy the low-height requirement, RPC is adopted to design the railway bridge. One simple-supported RPC T-beam with span of 32m is designed and applied in railway bridge engineering. The height of the beam is 1.8m and the height to span ratio is 1/17.8. It is supper low-height beam for railway bridges. The parameters of material properties, mixing proportion, section size and prestressed steel strand cable arrangement of the RPC T-beam are presented. The load bearing capacity, the deflection and the crack resistance safety coefficient are calculated and the results can satisfy the requirements of the code. It is useful for the design and application of RPC in structure engineering.