No abstract

In this work, to further investigate the vegetation concrete technology for slope protection, a total of 10 groups mix proportion specimens of porous concrete were designed and constructed. As a result, the impacts of different parameters include the fly ash and silica fume contents on the mechanical properties and porosity as well as the pH value of porous concrete were discussed. Meanwhile, ecomodified soil with resistance to the erosion of rainwater was sprayed on the surface of porous concrete for the survival of native grass growth. In addition, the growth characteristics of the Festuca arundinacea schreb (Chinese grass) within eco-modified soil on the surface of porous concrete were observed and monitored for 8 weeks including the average height, root system development and relative coverage of grass. The results show that the compressive strength and porosity of porous concrete measured after 28 days were at least 13Mpa and 21% respectively, indicating the porous concrete is suitable for the slope protection in practical engineering. Furthermore, the integration of eco-modified soil and porous concrete was successful, and all grass survived in the eco-modified soil and porous concrete environment for the duration of the observation period, and the coverage rate of vegetation reached 96% or above. It was also found that the roots system has permeated the pores of porous concrete and reached the bottom of porous concrete after 8 weeks.

To investigate the influence of corroded steel bars on seismic performance of reinforced concrete (RC) columns, eight fullscale RC columns were designed and fabricated, which were composed of one uncorroded RC column, three RC columns with longitudinal reinforcement corrosion and four stirrup-corroded RC columns. The electrochemical test was conducted to accelerate the corrosion of steel bars in RC columns, and the low-cyclic repeated loading tests on RC columns with corrosion-damaged steel bars were carried out. The seismic behavior indicators, including the hysteretic curves, skeleton curves, displacement ductility coefficient, stiffness degradation curves and energy dissipation capacity of corroded RC columns and uncorroded columns, were compared and discussed. The experimental results show that with the increase in steel bars corrosion degree, the pinch phenomenon of the hysteretic curve gradually increases, and the energy dissipation capacity, stiffness and plastic deformation capacity of specimen reduce significantly. The ductility and energy dissipation coefficient decreased by 20% and 36%, respectively, when the stirrups corrosion ratio of specimen reaches 15.2%, and a shear failure surface was formed in the plastic hinge zone at the foot of the columns, which leads to the change of failure mode from ductile bending failure to shear failure with poor ductility under the ultimate load for corroded columns. The influence of stirrup corrosion on the failure mode of specimens is remarkable, but the effect of longitudinal reinforcement corrosion is negligible for specimens with the corrosion ratio within 14.7%. The adverse effects caused by over 15.2% stirrup corrosion should be considered in seismic design of structures in seismic zone.

There are many horizontal joints on precast concrete (PC) wall panel structures, which certainly has a significant impact on the seismic behavior of structures. This paper proposes a novel alveolar-type horizontal joint, which has advantages of convenient and rapid assembly. Six precast concrete wall specimens with alveolar-type joints were designed and constructed, and they were weakly connected by spliced rebars anchored into grouted sleeves to meet the requirements of structural performance. The pseudo-static loading tests on these specimens were conducted to investigate the effects of influencing factors, such as the axial compression ratio, the thickness of wall (interface contact area), and the addition of a vertical grouted sleeve connection at the horizontal joint, on the seismic performance of PC walls. Analyses and comparisons were conducted in terms of the cracking propagation pattern, failure modes, force–displacement hysteretic curves, skeleton curves, bearing capacity, ductility factors, and energy dissipation of PC walls. It was concluded that the axial compression ratio and adding grouted sleeve connection had a significant influence on the cracking mode of PC walls, whereas the impact of the wall thickness was slight. The shear capacity and energy dissipation capacity of specimen dramatically enhanced by increasing the axial compression ratio or adding grouted sleeve connection. The PC wall exhibits good ductility after adding the vertical grouted sleeve connection at a horizontal joint. However, the ductility factor increases firstly and then decreases in the enhancement of the axial compression ratio. The reduction in wall thickness has remarkable impacts on the shear strength and energy dissipation capacity of specimens, but the influences on ductility were not significant. The prediction method for calculating the shear capacity of PC walls with alveolar-type horizontal joints was proposed based on the experimental data, and these calculated results are in good agreement with the experimental results.

In this paper, one novel solar adsorption watering tube was designed. Solar watering tube (SWT) is an independent unit producing water from air, which uses solar energy to drive the production process. Compared with the traditional methods of producing water, the production process of SWT bases on adsorption/desorption theory. The influence of operating conditions on the SWT was investigated. Under the typical weather conditions, as follows, the ambient temperature was about 20°C~35°C, ambient relative humidity was about 44%~74%, and the solar radiation was about 22MJ.d-1m-2, the adsorbent bed temperature could reach 222°C in the day and cooled down to about 40°C in the night. A single SWT could produce about 90ml water one day.