The recycle of the building and demolition waste could reduce project expenses and save natural resources as well as solve problem about environmental risks incurred during the disposal of building waste. In this study, waste C30 concrete is taken an experimental material. The mass loss, ultrasonic velocity, dynamic modulus of elasticity and cubic compressive strength of recycled coarse aggregate concrete whose coarse aggregate replacement percentage is 25%, 50%, 75%, and 100% are tested and compared with NAC when the cycles of freezing and thawing are 0, 25, 50, 75, 100, 125, 150, 175, and 200 times. The results show: (1) Generally, the loss of mass, ultrasonic velocity, dynamic modulus of elasticity and cubic compressive strength constantly increase with the growth of freezing and thawing cycles. (2) Compared with the recycled concrete of other replacement percentages, the RAC50 shows relatively close performance to NAC in mass loss, the change of dynamic modulus of elasticity and cubic compressive strength. (3) Performances of RAC25 specimens are better than the other RAC specimens for the ultrasonic wave velocity.
Liquid forging alias squeeze casting gives the combined advantage of casting and forging. Optimum process parameters are important to get a cost-efficient process. In this study, four materials have been identified, which are extensively used in industries. These materials are commercially pure Al and three Al-alloys namely, 2124, 2218 and 6063. The pouring temperature and the mold temperature is maintained at 700oC and 250oC respectively. The materials were developed at seven pressure variations from 0 to 150 MPa. The effect of the pressure on the microstructures, porosity, and hardness has been reported. The coefficient of solubility is estimated for all materials and a polynomial relationship is found to be the best fit with the applied pressure. The pressure of 100 MPa gives better increment in hardness. The melting point and the freezing coefficient of the materials under study have been determined. A linear relationship between the pressure and the freezing time is deduced. It is observed that the solubility and the freezing coefficients depend on the pressure as well, in addition to the composition and temperature.