In recent years,mineral admixtures are finding increasing applications in buildings and infrastructural development due to numerous advantages,such as higher strength and durability,concretes with these cementitious materials have similar properties with conventional concretes.Structural members made in combination with supplementary cementitious materials,when used in buildings,have to satisfy the durability,strength,and fire resistance requirements specified in designated building codes and standards.Although conventional concrete members have good fire resistance,some may not be true for concrete members casted with supplementary cementitious materials due to faster degradation of strength with temperature and occurrence of fire induced spalling.In addition,one of the primary problems related to concrete structures is corrosion of reinforced concrete induced by carbonation of concrete and chloride-ion ingress.In many cases,depth of carbonation on concrete structures is used to evaluate concrete service life.Factors that can substantially affect carbonation and chloride-ion resistance of concrete are temperature,relative humidity,cement composition,concentration of external aggressive agents,quality of concrete,and depth of concrete cover.At present,there is lack of data on properties of concrete under high temperature exposure specific to different replacement of ground-granulated blast-furnace slag（GGBS）cement（0%（reference）,30%（slag）,50%（slag）,and 70%（slag））,in different curing environments.Also,there is no methodology to account for the effect of heating duration on fire resistance of GGBS cement concrete.To overcome these knowledge gaps,an experimental study is undertaken as part of this thesis.The effect of curing temperature on the properties of slag cement concrete after high-temperature exposure was studied,and elevated curing temperature（45 ±2 ℃and 95%relative humidity（RH））was selected to compare with the standard curing temperature（20±2℃ and 95%RH）.Four different concrete mixes with the same mix proportion,except for different slag replacement ratios,were used:0%（reference）,30%（slag）,50%（slag）,and 70%（slag）.After high temperature exposure at 200,400,600,and 800℃,the effect of slag replacement,high temperature,and curing temperature on the compressive strength and mineralogical and microstructural properties of slag cement concrete were studied.The microstructural and mechanical properties of concrete containing high volume slag（ground granulated blast furnace slag）cement activated by Ordinary Portland cement（OPC）were also investigated at standard curing temperature and at a range of progressively high temperature.The slag cement was activated by portlandite（CH）formed during the hydration of OPC.The durability of concrete produced by combining ordinary Portland cement（OPC）with ground-granulated blast-furnace slag（GGBS）was investigated as part of the durability study.Concrete specimens casted with OPC and various percentages of GGBS（0,30,50,and 70%）were subjected to extensive experimental tests reproducing basic freeze-thaw cycles and a chloride-ion attack to determine their combined effects and the resultant concentrations of free water-soluble chloride ions within the concrete samples.The porosities and pore-size distributions were determined via mercury intrusion porosimetry（MIP）.Furthermore,the chloride ion threshold levels and diffusion coefficients were analyzed using NELD-CL420 ion-selective electrodes and NELD-AL492 rapid chloride permeability test apparatus,respectively.Furthermore,the concretes with OPC were compared to concretes with various percentages of GGBS,to assess the carbonation depth as well as rate of carbonation of GGBS-based concretes,under both accelerated carbonation（15±2%carbon dioxide（CO2）concentration）and natural carbonation exposure conditions.Test results indicated that the compressive strength of concrete cured for 7 d at elevated temperatures was increased by 28.2%,20.7%,28.8%,and 14.7%compared with that cured at the standard curing condition at slag percentages of 0,70,50,and 30%,respectively.X-ray diffraction（XRD）and scanning electron microscope（SEM）results revealed that concrete cured at elevated temperatures exhibited a more condensed phase and contained a higher percentage of hydrates than that cured for 7 d in the standard curing condition.However,after 56 d of curing,concrete in the standard curing condition exhibited a more stable phase and a higher concentration of hydrates.When the exposure temperature increased from 200℃ to 400℃,the compressive strength was increased for all concrete groups except for the group casted from 30%OPC and 70%slag cement.The SEM results for the 7th and 56th day curing the concrete groups casted from 30%slag and 70%OPC,50%slag and 50%OPC showed a well-structured C-S-H gel compared to the reference concrete group casted from 70%slag and 30%OPC.In addition,the SEM investigation revealed that the concrete casted from 30%slag and 70%OPC have more structured C-S-H gels and better fire resistance compared to the other concrete groups.The presence of slag cement in concrete mix has an influence on the thermal diffusivity property.Test data is used as a function of temperature and slag replacement to establish high temperature relations for thermal properties.The proposed thermal property relationships can be used as input data for validation in computer programs and to evaluate the response of OPC and slag blended Portland cement concrete structures subjected to high temperature exposure.Result for durability of GGBS concrete test shows that,concrete specimens containing GGBS exhibited greater resistance to chloride ion penetration than the conventional concrete specimens.Further,this resistance increased with the increasing percentage of GGBS,and concrete specimens with higher percentages of GGBS exhibited greater resistance to the combined effects of chloride ion attack and freeze-thaw exposure.Finally,MIP results indicate that the porosities of the specimens decreased with increasing GGBS percentage and resulted in lower concentrations of water-soluble chloride ions.In addition,regarding to carbonation induced corrosion test,the experimental tests reveal that GGBS cement concrete has a lower carbonation resistance than OPC concrete due to the consumption of portlandite by the pozzolanic reaction.The combination of 70%OPC and 30%GGBS behaved well enough with respect to accelerated carbonation exposure,the depth of carbonation being roughly equivalent to that of control group（100%OPC）.The results also show that rate of carbonation becomes more sensitive as the percentage of GGBS replacement increases（binder ratio）rather than duration of curing.Concretes exposed to natural carbonation（indoor）achieved lower carbonation rates than those exposed to accelerated carbonation.