Stone powder and others waste powder causes serious harm to the environment, society, ecosystem and human well-being, applying it to concrete is a path of green and effective. In this study, a series of tests was carried out on manufactured sand concrete with different granite porphyry powder contents. The results showed that when the stone powder content was lower than 8%, the cracking resistance, compressive strength, chloride ion permeability resistance, and sulfate attack resistance of the concrete were significantly improved with an increase in the stone powder content. Although the early shrinkage rate of the concrete also increased with the increase in the stone powder content, the increase rate was slow. At the microstructure level, an appropriate amount of stone powder exhibited the ‶filling effect" and "nucleation effect," which were conducive to the improvement of the concrete mechanical properties and durability. However, with an increase in the stone powder content, the early shrinkage of the concrete increased sharply when the stone powder content exceeded 8%, and the crack resistance, compressive strength, and chloride ion permeability resistance of the concrete decreased. At this time, the stone powder had a "diversified effect" on the microstructure of the concrete, and the existence of a large amount of stone powder was not conducive to the development of certain properties of the concrete. It is feasible to prepare concrete by replacing manufactured sand with an appropriate amount of stone powder and others waste powder, which can not only improve the performance of concrete, but also save cost, energy, avoid manpower and material consumption in waste powder disposal. The research conclusion shows that the allowable value of the stone powder content can be appropriately increased according to the actual application in concrete, which is an efficient, green disposal path for stone powder and other waste powder.

The poor early shrinkage and cracking performances of manufactured sand concrete, waste powder concrete, and recycled aggregate concrete are the main difficulties in engineering applications. To solve these problems, early shrinkage and cracking, strength, and impermeability tests were performed on high-volume stone powder manufactured sand concrete mixed with fly ash and slag powder (FS), a shrinkage-reducing agent (SRA), polyvinyl alcohol (PVA) fibers, and a superabsorbent polymer (SAP). Furthermore, the microstructures and pore structures of these concretes were revealed using nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The results showed that the mixture of FS, SRA, PVA fibers, and SAP could effectively inhibit the shrinkage strain and cracking area of the concrete. The effect of the SAP on reducing the early shrinkage of the concrete is the greatest, and the shrinkage strain can be reduced by 76.49%. The PVA fibers had the most obvious effect on inhibiting the early cracking of the concrete, and the total cracking area was reduced by 66.91%. Significantly, the incorporation of the FS can improve the particle gradation and the pore structure and improve its compactness. The PVA fibers not only provide good carriers for cement-based materials but also enhance the bonding force between the particles inside the concrete, filling the pores inside the concrete, inhibiting the loss of water, and reducing the generation of internal microcracks. The FS and PVA can reduce the shrinkage and cracking risk and improve the strength and impermeability of the concrete. Although the SRA and SAP can reduce the shrinkage and cracking risks, it will lead to a significant decrease in the later strength and impermeability. The main reason is that the SRA leads to an increase in micropores in the matrix and microcracks near the aggregate, which are not conducive to the development of the strength and penetration resistance of the MS. Similarly, the SAP can promote the rapid formation of ettringite (Aft) at an early age and improve the early shrinkage, early cracking, and early strength of the concrete. However, with an increase in age, the residual pores, after SAP dehydration, will cause the deterioration of the concrete pore structure, resulting in the deterioration of the strength and impermeability.

The structure of a variable friction self-centering damper (VFSCD) and the main key parameters for controlling its hysteretic performance are introduced. The performance evaluation index and calculation method of each index of the VFSCD are defined. The theoretical equation and simulation model of the VFSCD are established and compared with the test results. Based on the verified simulation model, the local behavior and stress mechanism of the key components of the VFSCD are further analyzed. The results show that the VFSCD hysteresis curves are full and have good energy dissipation capacity, and there is no residual deformation or damage to each component after unloading. With the increase in the number of wedge groups, the yield load, loading stiffness and bearing capacity of the VFSCD increase significantly, and the unloading stiffness and restoring force decrease obviously. Importantly, the test curve, the theoretical curve, and the finite element hysteresis curve are in good agreement. Although there are some errors in the test results, the theoretical curves are basically consistent with the simulation curves. The simulation model established in this research can effectively reflect the local behavior and stress mechanism of VFSCD.