Suitable methods for enhancing the volume stability of steel slag utilized as fine aggregate were determined. The effects of steam treatment at 100 ℃ and autoclave treatment under 2.0 MPa on the soundness of steel sl...Suitable methods for enhancing the volume stability of steel slag utilized as fine aggregate were determined. The effects of steam treatment at 100 ℃ and autoclave treatment under 2.0 MPa on the soundness of steel slag sand were investigated by means of powder ratio, linear expansion, compressive and flexural strength. DTA, EDX, XRD and ethylene glycol methods were employed to analyze both the treated slags and susceptible expansion grains. Experimental results indicate that powder ratio, content of free lime and rate of linear expansion can express the improvement in volume stability of different treated methods. Steam treatment process cannot ultimately prevent specimens from cracking and decrease of strength, but mortar made from autoclave treated slag keeps integration subjected to hot water of 80℃ until 28 d and its strength do not show significant decrement. The hydration of over-burn free lime and periclase phase are the main cause for the disintegration or crack of untreated and steam treated steel slag＇s specimens. Autoclave treatment process is more effective than steam treatment process on enhancement of volume stability of steel slag.展开更多
James Watt contributed significantly to the development of the thermodynamics of energy conversion as a science. Several of his ideas are now integral part of thermodynamics, but Watt as their creator is not mentioned...James Watt contributed significantly to the development of the thermodynamics of energy conversion as a science. Several of his ideas are now integral part of thermodynamics, but Watt as their creator is not mentioned. This paper presents some of Watt’s concepts of energy conversion, including his thermodynamic analysis of the Newcomen steam engine that marks the beginning of thermal engineering. The analysis illuminated the causes of the enormously high heat losses in the installation and showed the ways for their reduction. This led him to a new conception of the steam engine with a separate condenser. Not less important was Watt’s determination of some physical properties of water and steam used as the working substance. In the experiments he observed the decrease of the latent heat of steam with increasing temperature and its disappearance at very high temperature led him to postulate the existence of a thermodynamic critical state of water. He introduced the work associated with volume change into thermodynamics and illustrated it graphically. Several of Watt’s numerous ideas deserve to be included into the history of the thermodynamics of energy conversion but they are rarely mentioned in the scientific literature. Arguably the most important is the First Law of Thermodynamics, which he introduced in his 1769 patent and related works in 1774 and 1778.展开更多
基金the National Natural Science Foundation of China (No.50678139)
文摘Suitable methods for enhancing the volume stability of steel slag utilized as fine aggregate were determined. The effects of steam treatment at 100 ℃ and autoclave treatment under 2.0 MPa on the soundness of steel slag sand were investigated by means of powder ratio, linear expansion, compressive and flexural strength. DTA, EDX, XRD and ethylene glycol methods were employed to analyze both the treated slags and susceptible expansion grains. Experimental results indicate that powder ratio, content of free lime and rate of linear expansion can express the improvement in volume stability of different treated methods. Steam treatment process cannot ultimately prevent specimens from cracking and decrease of strength, but mortar made from autoclave treated slag keeps integration subjected to hot water of 80℃ until 28 d and its strength do not show significant decrement. The hydration of over-burn free lime and periclase phase are the main cause for the disintegration or crack of untreated and steam treated steel slag＇s specimens. Autoclave treatment process is more effective than steam treatment process on enhancement of volume stability of steel slag.
文摘James Watt contributed significantly to the development of the thermodynamics of energy conversion as a science. Several of his ideas are now integral part of thermodynamics, but Watt as their creator is not mentioned. This paper presents some of Watt’s concepts of energy conversion, including his thermodynamic analysis of the Newcomen steam engine that marks the beginning of thermal engineering. The analysis illuminated the causes of the enormously high heat losses in the installation and showed the ways for their reduction. This led him to a new conception of the steam engine with a separate condenser. Not less important was Watt’s determination of some physical properties of water and steam used as the working substance. In the experiments he observed the decrease of the latent heat of steam with increasing temperature and its disappearance at very high temperature led him to postulate the existence of a thermodynamic critical state of water. He introduced the work associated with volume change into thermodynamics and illustrated it graphically. Several of Watt’s numerous ideas deserve to be included into the history of the thermodynamics of energy conversion but they are rarely mentioned in the scientific literature. Arguably the most important is the First Law of Thermodynamics, which he introduced in his 1769 patent and related works in 1774 and 1778.
