This research study used metakaolin as a raw material, a mixed solution of sodium hydroxide and sodium silicate as an alkali excitant, and a graphene dispersant as an additive to manufacture a graphene geopolymer sample. The compressive strength and bending strength of the sample were tested. The results showed that the geopolymer hydration products were observed to be more compact, and the internal porosity was reduced after the addition of the graphene. The geopolymer strengths had been obviously increased, and the compressive strength and bending strength reached 46.9MPa and 6.7MPa, respectively. However, the graphene’s role in improving the strength of the original geopolymer became gradually weakened when the addition amounts of the graphene were increased to a certain extent. Furthermore, the role of the graphene in improving the compressive strength of the geopolymer was determined to gradually decrease with the increase in the content of sodium hydroxide in the alkali excitant.

In this study, in order to examine the impact properties of a stainless steel reinforced concrete bridge pier under the conditions of horizontal impact load effects, a multifunction ultrahigh heavy drop hammer impact test system was utilized. The stainless steel reinforced concrete bridge piers had different impact energies, and the impact force time-history, displacement time-history, and strain time-history curves, as well as the crack developing state, were obtained during the testing. The test results showed that the peak values of the impact force, strain, and displacement increased with the increase of the impact energy under the impact load, and the fluctuation frequency also increased. The crack development was mainly concentrated in the lower frontal section of the bridge pier, as well as the middle and lower sections of the back of the bridge pier.

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Mechanical properties and fracture mechanism of quasi-brittle material are considered largely relied on the mechanical properties of meso-components and the structure of how these components are combined together. In recent practice of numerical simulation, it has become a trend to consider the real structure of materials as accurately as possible. In this paper, macroscopic and mesoscopic bending behaviors of steel fiber reinforced reactive powder concrete (RPC) slabs with fiber volume content between 0.0% and 2.5% were investigated with both experimental tests and numerical simulations. Images obtained from X-ray CT were input into a program named RFPA3D-CT to build a modified 3D FEM model. The results indicate that the steel fibers can help to convert a brittle failure pattern of RPC into a ductile one. Compared with the specimen without fibers, the crack tortuosity and the bending strength of the specimens fiber content of 2.5% are increased by 20.25% and 308.80%, respectively. The bending performance of the numerical results obtained by the modified model are in good agreement with the experimental results, and the relative error values of the tortuosity and bending strength in the simulation compared with those in the experiment are all less than 15%. Moreover, AE parameters and AE curves obtained in RFPA3D-CT can be used to reveal the initiation and propagation process of cracks in RPC.

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