Papers by Keyword: Reactive Powder Concrete (RPC)

Abstract: Basing on the basic preparation principle of reactive powder concrete, through mixing the new active component of slag, this thesis aims to confect new-type cement-based material with super high performance. As illustrated from the experiments of resistance to chlorine ion permeability, this type of concrete is with extremely compact structure and higher resistance to chlorine ion permeability compared with other cement-based materials. Silica fume presents the most important promotion effect on its resistance to chlorine ion permeability. Steel fiber and standard sand also help to enhance its impermeability. Through the analysis and the research on microstructure realized by X-ray Diffraction, mercury penetration experiment and SEM, all these views have been proved.

Abstract: 87 prismatic flexural steel fiber-reinforced reactive powder concrete (RPC) specimens with the size of 40mm×40mm×160mm were tested as well as 87 dumbbell-shaped axis tensile RPC specimens after being exposed to different high temperatures. The effect of steel fiber content and heating temperature on the flexural and tensile strength of steel fiber-reinforced RPC was analyzed. With the steel fiber content increasing, the flexural and tensile strength of steel fiber-reinforced RPC after high temperature improve significantly, and they increase first and then decrease with the heating temperature elevated, and the critical temperatures are 200¡æ and 120¡æ, respectively. Equations are established to express the relationship between the flexural and tensile strength of steel fiber-reinforced RPC and the heating temperature. The theoretical curves are in good agreement with the test data.

Abstract: In this paper, the thermophysical properties, such as thermal conductivity, thermal diffusivity, specific heat capacity and linear thermal expansion of reactive powder concrete (RPC) with different steel fiber volumetric fractions are investigated by means of thermophysical experiments. The empirical relationships of thermophysical properties with temperature and fiber volume are established. The results indicate the temperature and fiber volumetric fractions have different effects on the thermal properties of RPC.

Abstract: The excellent mechanical properties of reactive powder concrete (RPC) are tested with under the condition of hot water conservation. Four batches of 19 specimens are prepared to determine the best ratio of RPC component materials. The variation of strength (compressive strength, flexural strength) of RPC with fly ash or tailings powder is studied with two batches of 10 specimens, and its optimal dosage is determined.

Abstract: Based on the data obtained by the strength test of simply supported Reactive Powder Concrete (RPC) plate, the calculation method of simply supported RPC plate is studied and the method is proved to be feasible. In addition, based on the analysis of the steel fiber in the simply supported RPC plate, some suggestions, which can improve the flexural strength of simply supported RPC plate, are proposed。

Abstract: Based on uniaxial tensile test, the complete uniaxal tensile stress-strain curve of Reactive Powder Concrete (the steel fiber content by volume is V_f =1%, 2%) was obtained, and the fracture energy of RPC specimens with cross-section of 100mm by 100mm was calculated. The test was finished through Universal Testing Machine without any stiffness-strengthen devices. In order to solve the stress concentration problem, a self-designed uniaxial tensile test equipment was developed, and a dumbbell-shaped specimen was used in the test. The results indicate that the fracture energy of RPC increased as well as the increasing of V_f.

Abstract: Reactive powder concrete (RPC) containing blast furnace slag prepared for hydraulic structure with a designed strength of 150 MPa is examined. We first investigate mixture proportions of RPC to fit the strength requirement, and then, concentrate on the material with 50% replacement of silica fume by blast furnace slag to study seismic resistant properties. Results indicate that curing process and steel fiber can enhance the compressive strength, flexural strength, shear strength and fracture toughness. With 210°C curing, flexural strength of RPC containing 2% steel fibers reaches 91 MPa, almost three times without the fibers. Meanwhile, the shear strength is 47.8 MPa. Dynamic stress-strain curves determined by SHPB test display that the compressive strength of RPC increases with increasing applied strain rate. Applied strain rate dominates the stress-strain behavior and fracture energy of RPC. Toughness index of RPC is improved powerfully by adding a few steel fibers. The fracture toughness of RPC with 50% slag replacement comes to 1.08 MPa·m^1/2, and reaches 2.67 MPa·m^1/2 as 2% steel fibers are added.

Abstract: Close packing of the fine particles is one of the core technologies of preparation of reactive powder concrete. This paper introduces the concept of soil liquid limit in close packing evaluation. Theoretically, the closer of particles pack, the lower is the water demand. The mixture with a lower water demand is expected to have a lower liquid limit. Mixtures were obtained by measuring the cone penetration at different moisture content. By means of numerical fitting and linear interpolation, the liquid limits of the mixtures were obtained，where the software of Matlab was used. The close packing condition of the powders particles could be predicted according to the liquid limits. Strength test confirmed that application of liquid limit in mixing proportion design of reactive powder concrete is feasible. So, this may be a new way for the preparation of reactive powder concrete.

Abstract: In order to systematically study dynamic mechanics character of reactive powder concrete (RPC), impact compression experiments and impact flattened Brazilian disc specimens of RPC have been investigated with modified split Hopkinson pressure bar (SHPB) experimental facility using brass pulse shaper, curves about stress versus strain and other parameters at strain rates of 20.3/s~137.0/s were obtained from impact compression. The dynamic tensile strength and tensile failure strain at strain rates of 3.4/s~26.2/s were obtained from impact flattened Brazilian. For comparison, the quasi-static compress and split tension of RPC were obtained with an MTS 810 materials test system and CSS-88500 electron universal material testing machine.The experimental result show that dynamic compression strength , elastic modulus and failure strain,dynamic tensile strength and failure strain significantly increase comparing to quasi-static experiment, RPC have the character of impact harding and ductility enhancement. RPC exhibit excellent failure patterns at high strain rate. Whether impact compression or impact splitting under strain rate including this paper ’s experiments, the relationship between the DIFC or DIFT and the logarithm of strain rateis linear.

Abstract: Based on experiments of uniaxial compression and flexural experiments, the basic mechanical properties (compressive strength and flexural strength) of reactive powder concrete (RPC) were investigated, the effect of the steel fiber content on mechanical properties of RPC was studied in this work. The resu1ts indicate that the axial compressive strength of RPC had no obvious change with the change of steel fiber content. When the steel fiber content varied from 1.0% to 2.0%, the flexural strength of RPC had no obvious change.When the steel fiber content varied from 2.0% to 5.0%, the flexural strength of RPC increased dramaticlly with the increase of steel fibers content. According to experiment curves, an equation for the compressive stress-strain curve of RPC was deduced with different stee1 fiber content.