Facing the cement and concrete development process, reducing greenhouse gases and the consumption of natural resources has become an important issue. To reduce the cement content in concrete, the increased use of concrete combining large amounts of industrial by-products is expected. Ground granulated blast furnace slag (GGBFS) has been used as a supplementary cementitious material in ordinary Portland cement (OPC) concrete. In this study, GGBFS at different cement replacement ratios of 0%, 20%, 40%, and 60% by weight were used to produce concrete. Compressive strength test, water absorption, electrical resistivity, and rapid chloride penetration test (RCPT) were performed to investigate the effect of GGBFS on compressive strength and durability of concrete. Test results show that GGBFS concrete with 40% cement replacement (G40) has the highest compressive strength. The water absorption and chloride permeability reduced with the increasing cement replacement percentage by GGBFS. Meanwhile, the electrical resistivity increased with an increasing GGBFS replacement percentage. Based on the results, GGBFS concrete with 40% cement replacement seems to be the optimum replacement in this study.

The research aims to investigate the effect of elevated temperature on the compressive strength of concrete containing waste tile aggregate. Two water-to-cement ratios (w/c = 0.4 and 0.6) and three replacement ratios of waste tile aggregate (0%, 50% and 100%) were selected for producing concrete specimens. Experiment results showed that the slump of concrete were increased with the increase of the replacement ratio of waste tile aggregate. The compressive strength of concrete decreased with the increase of waste tile aggregate. The concrete with higher w/c of 0.6 can present equivalent compressive strength for that of the replacement ratio of waste tile aggregate under 50%; on the contrary, the concrete with lower w/c of 0.4 can have higher compressive strength for the replacement ratio increased to 100%. In addition, when the subjected temperature exceeded 440°C and raised to 800°C, the compressive strength of concrete decayed seriously and the residual strengths was almost the same at 800°C. Consequently, the fire resistance of waste tile aggregate concrete may be comparable to that of natural aggregate concrete.

In view of the fact that construction of modern buildings tends to use a high ratio of iron materials, this study aimed to obtain the ratio of components of steel’s microstructure under different test conditions by heating a A36 steel sheet commonly used in buildings, and applying metallographic replication testing. When the steel sheet was heated above 800°C and then rapidly cooled by water, the ratio of components of the structure were changed dramatically: components such as pearlite disappeared, ferrite was reduced from 90% to a low of 20%, bainite was increased to a maximum of 35%, and martensite was increased to a maximum of 45%. Since the substantial increase of martensite phase in this study led the microstructure of iron material to become thinned out and scattered, the ductility of such material was significantly reduced accordingly, thereby making the steel sheet easily broken. This study expected to provide the test findings of the mechanical behavior and metallographic structure of steel, after being heated to a high temperature and then naturally cooled, to other relevant units of construction engineering to serve as reference for their evaluation of non-destructive testing of steel structures.