Research of In-Service Regulatory Signs Sheeting, Retro-Reflectivity, and Deterioration Characteristics

Author(s):  
Ming Jiang ◽  
Rui Zhou
Author(s):  
Frank Navarro Tamayo ◽  
Ana Luisa Rodriguez Quesada ◽  
Veronica Avila Ayon ◽  
Alexander Justel Betancourt

Environmental pollution and natural degradation of materials cause deterioration in buildings, initiating pathological processes that require conservation actions. Architectural Photogrammetry will be discussed as a tool to identify different pathologies on buildings and to accurately measure deflections. A photographic study was conducted of the most common deflections on reinforced concrete structures, with samples of different ages and locations exposed to various environments within Holguin Province in Cuba to detect deterioration characteristics, causes and possible treatments. A comparative analysis of other common methods and instruments currently used to measure structural pathologies highlights the efficiency of architectural photogrammetry. Photogrammetry is suitable to study the most common pathologies, their causes, and potential solutions. These include: cracks, fissures, deflection in beams, footing settlement, slenderness in columns, and more. In addition to the scope and efficiency of photogrammetry, this technology also facilitates studying inaccessible points on large elements. The instantaneous recording of accurate data about physical objects gives photogrammetry advantages over conventional structural analysis methods.


1997 ◽  
Vol 36 (Part 1, No. 7A) ◽  
pp. 4392-4396
Author(s):  
Changmin Yuan ◽  
Noboru Yoshimura ◽  
Jangseob Lim ◽  
Hiroyuki Miyata ◽  
Toshio Niwa

1988 ◽  
Vol 36 (6) ◽  
pp. 199-203 ◽  
Author(s):  
M. Edge ◽  
N.S. Allen ◽  
T.S. Jewitt ◽  
J.H. Appleyard ◽  
C.V. Rorie

2020 ◽  
Vol 24 (1) ◽  
pp. 55-59
Author(s):  
Guopeng Wu ◽  
Wenwu Chen ◽  
Kai Cui

In order to study the influence of dry-wet cycling on the deterioration characteristics of gypsum rocks and solve the problems encountered in engineering construction, in this study, gypsum rocks are taken as the research object. With the combination of laboratory test and theoretical analysis, the numerical simulation of particle flow is carried out, and the deterioration characteristics of physical and mechanical properties of gypsum rock under dry-wet cycling are studied. The results show that gypsum, quartz, zeolite and dolomite are the main components of gypsum rocks. Gypsum occupies the most components in gypsum rocks, so the various characteristics of gypsum greatly affect the characteristics of gypsum rocks. The process of water absorption and loss of gypsum is similar, which shows that the rate of water absorption or loss of gypsum is faster in the early stage, and tends to be stable in the later stage. The curve of the whole process of water absorption and loss is fitted by negative exponential function, and the effect is better. The larger the porosity of gypsum rock is, the better its water absorption performance is. Intergranular pore, dissolution pore and dissolution pore are the main pore types of gypsum rock. Intergranular pore is the main water absorption channel of gypsum rock. The cumulative water absorption increases with the increase of wetting and drying cycles. The change of water absorption curve is mainly manifested in water absorption rate and time. The more the number of wet-dry cycles is, the higher the water absorption rate in the early stage of water absorption is, the closer the characteristic curve to the coordinate axis of water absorption is, and the shorter the water absorption time is. In contrast, the shape difference of water loss curve is very small. It can be seen from this that in the process of wetting and drying cycle, the hydrophysical and hydrochemical processes promote each other, which changes the crystal structure and pore structure of gypsum rocks, reduces the crystal strength and increases the porosity, thus leading to the deterioration of the mechanical properties of gypsum rocks.


2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Runke Huo ◽  
Tian Qiu ◽  
Yanling Liang ◽  
Shuguang Li ◽  
Meiting Qian

The physicomechanical deterioration characteristics of sandstone subjected to H2SO4, HCl, and H2O solutions of different pH values are studied by the method of long-term accelerated immersion. The quantitative relationships between the damage variables based on CT (computer tomographic identification technology) numbers and the immersion time, the uniaxial compressive strength, the peak point strain, and the elastic modulus of rock samples are analyzed. The test results indicate that the pH value of immersion solutions, the dissolution rate of Ca2+ and Na+, and the quality change of rock samples show visible stage characteristics under acidic environment. With the soaking time extended, the pH value of solutions increases gradually, and the quality change of rock samples decreases gradually. The smaller the pH value of immersion solutions is, the higher the dissolution rate of Ca2+ and Na+ is. However, the cation dissolution rate under a weak acid environment with a high pH value has little difference with that under the distilled water (pH = 7). With the increase of the soaking time and the acidity, the compaction stage of rock samples becomes longer, the elastic stage becomes shorter, the deterioration degree of mechanical parameters becomes more extensive, and the destruction of sandstone samples shows ductility characteristics increasingly. The corrosion degree of corroded sandstone samples is quantitatively represented by microscopic damage variables based on CT numbers. The regression analysis results show that damage variables of acid-corroded sandstone samples have a power function relationship with soaking time and an exponential function relationship with peak strength, peak point strain, and elastic modulus.


Sign in / Sign up

Export Citation Format

Share Document