Radiation shielding concrete is widely used in nuclear power plants, accelerators, hospitals, etc. With the development of nuclear industry technology, research on radiation shielding material properties is of great importance. Research on properties of radiation shielding concrete with different aggregates or admixtures and the effect of high temperature on the performance of shielding concrete are introduced. Along with the nuclear waste increase, shielding concrete durability and nuclear waste disposal are getting paramount.
Based on the current color fastness standard of textiles at home and abroad, this paper gives a comparative analysis of the testing standard of related indicators, discuss the major color fastness of textiles including color fastness to water, to perspiration, to rubbing, to laundering. The quantified data of the sample test results show that there are some differences among the test methods, the equivalent of quantitative values and the requirements of indicator in GB, ISO, AATCC.
This paper carries out dynamic tests of self-compacting prestressed concrete beams, 10 simply-supported and 5 free, then simulates modal analyses. It shows that, via comprehensive analyses of the first four natural frequencies and modes, the simple support can not achieve the ideal confinement effect for dynamic tests. Especially the tested high frequencies and modes are obviously different from corresponding theoretical values, instead the same as elastic-supported beams. The support plays the role of elastic one. The conclusions will provide meaningful references to further researches on prestressed concrete beams such as improving the accuracy of tests, dynamic analyses and theoretical frequency calculation.
In this paper, modal characteristics of self-compacting concrete (SCC) beams were studied through experiment. 3 self-compacting concrete beams were gradually damaged and then subjected to vibration test in free-free boundary conditions after each load step. From analysis, eigenfrequencies could indicate the existence of damage but it could not represent the damage locations. Modal Assurance Criterion (MAC) is lesser reliable to indicate crack damage compare to eigenfrequencies. Next to these, capacity for damage detection and localization of Coordinate Modal Assurance Criterion (COMAC) and the flexibility matrix method are also examined and compared. This paper introduces in detail the dynamic properties and damage localization methods in SCC, which provide basal databases of damage diagnosis for SCC structures and promote the popularization of SCC in civil infrastructures.
The high temperature stability of AC-16, AC-13, AC-20 under specimen thickness of 5cm and 6cm is studied through indoor asphalt mixture high rutting test, Through comparison and analysis about experimental data, it is found that the stability of AC-16, AC-13, AC-20 asphalt mixture at high- temperature decreases in turn. It is shown that thickness changes did not affect the change trend of the high temperature stability under gradation change, and the stability of AC-16 at high-temperature is the best, the AC-13 is second and the AC-20 is less.
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