Relation between Modulus of Elasticity and Compressive Strength of Ultrahigh-Strength Mortar with Mixed Silicon Carbide as Fine Aggregate

Ultrahigh-strength mortar mixed surface-oxidized silicon carbide as a fine aggregate was prepared by means of press-casting followed by curing in an autoclave. The relation between modulus of elssticity up to 111 GPa and compressive strength up to 360 MPa of mortar mixed silicon carbide was discussed and it was revealed that the contributions of the aggregate hardness and of the interfacial strength between the aggregate and the cement paste on the elasticity of mortar were imporant.

Effects of Frost-damage on Mechanical Performance of Concrete

The aim of this study is to provide the quantificational change laws of strength,stiffness,and deformation capacity of frost-damaged concrete relating to a united index,the data were obtained by different researchers.Then the index of relative compressive strength（RCS） was introduced as the indicator of frost damage and a large number of mechanical performance testing data of frost-damaged concrete were collected and analyzed.By curve fitting,the correlations between RCS and the initial elastic modulus,the strain at peak compressive stress,and biaxial compressive strength,and tensile strength,and the strain at peak tensile stress were established.Thereafter,the analytical stress-strain response of frost-damaged concrete under monotonic loading was presented using RCS and compared with that of the experimental data.Moreover,an isotropic elastoplastic damage model of frost-damaged concrete subjected to repeated loading was established.Finally,we can systematically estimate the effects of frost-damage on the mechanical performance of concrete,which can be provided for the numerical simulation of frost-damaged concrete structures.

Mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions

To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation,and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the420 th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.