Evaluation of Carbonation Resistance of Paint Coated Concrete in Real Environment of Nakhon Pathom Province

The article deals with the measurement of dynamic effects that are transmitted to the driver (passenger) when driving in a car over obstacles. The measurements were performed in a real environment on a defined track at different driving speeds and different distributions of obstacles on the road. The reaction of the human organism, respectively the load of the cervical vertebrae and the heads of the driver and passenger, was measured. Experimental measurements were performed for different variants of driving conditions on a 28-year-old and healthy man. The measurement’s main objective was to determine the acceleration values of the seats in the vehicle in the vertical movement of parts of the vehicle cabin and to determine the dynamic effects that are transmitted to the driver and passenger in a car when driving over obstacles. The measurements were performed in a real environment on a defined track at various driving speeds and diverse distributions of obstacles on the road. The acceleration values on the vehicle’s axles and the structure of the driver’s and front passenger’s seats, under the buttocks, at the top of the head (Vertex Parietal Bone) and the C7 cervical vertebra (Vertebra Cervicales), were measured. The result of the experiment was to determine the maximum magnitudes of acceleration in the vertical direction on the body of the driver and the passenger of the vehicle when passing a passenger vehicle over obstacles. The analysis of the experiment’s results is the basis for determining the future direction of the research.

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Carbonization Durability of Two Generations of Recycled Coarse Aggregate Concrete with Effect of Chloride Ion Corrosion

Sustainability ◽

10.3390/su122410544 ◽

2020 ◽

Vol 12 (24) ◽

pp. 10544

Author(s):

Chunhong Chen ◽

Ronggui Liu ◽

Pinghua Zhu ◽

Hui Liu ◽

Xinjie Wang

Keyword(s):

Compressive Strength ◽

Coarse Aggregate ◽

Chloride Ion ◽

Total Porosity ◽

Recycled Concrete ◽

Carbonation Depth ◽

Aggregate Concrete ◽

Recycled Coarse Aggregate ◽

Carbonation Resistance ◽

Two Generations

Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.

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Analysis of Occlusion Effects for Map-Based Self-Localization in Urban Areas

Sensors ◽

10.3390/s21155196 ◽

2021 ◽

Vol 21 (15) ◽

pp. 5196

Author(s):

Yuki Endo ◽

Ehsan Javanmardi ◽

Shunsuke Kamijo

Keyword(s):

Urban Areas ◽

Structural Information ◽

Average Error ◽

High Definition ◽

Geometrical Structures ◽

Real Environment ◽

Surrounding Environment ◽

Localization Errors ◽

Stable Estimation ◽

High Level

A high-definition (HD) map provides structural information for map-based self-localization, enabling stable estimation in real environments. In urban areas, there are many obstacles, such as buses, that occlude sensor observations, resulting in self-localization errors. However, most of the existing HD map-based self-localization evaluations do not consider sudden significant errors due to obstacles. Instead, they evaluate this in terms of average error over estimated trajectories in an environment with few occlusions. This study evaluated the effects of self-localization estimation on occlusion with synthetically generated obstacles in a real environment. Various patterns of synthetic occlusion enabled the analyses of the effects of self-localization error from various angles. Our experiments showed various characteristics that locations susceptible to obstacles have. For example, we found that occlusion in intersections tends to increase self-localization errors. In addition, we analyzed the geometrical structures of a surrounding environment in high-level error cases and low-level error cases with occlusions. As a result, we suggested the concept that the real environment should have to achieve robust self-localization under occlusion conditions.

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Auditory perception versus automatic estimation of location and orientation of an acoustic source in a real environment

Acoustical Science and Technology ◽

10.1250/ast.31.309 ◽

2010 ◽

Vol 31 (5) ◽

pp. 309-319 ◽

Cited By ~ 2

Author(s):

Alberto Yoshihiro Nakano ◽

Seiichi Nakagawa ◽

Kazumasa Yamamoto

Keyword(s):

Auditory Perception ◽

Acoustic Source ◽

Real Environment ◽

Automatic Estimation

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Durability and Time-Dependent Properties of Low-Cement Concrete

Materials ◽

10.3390/ma13163583 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3583 ◽

Cited By ~ 1

Author(s):

Keila Robalo ◽

Eliana Soldado ◽

Hugo Costa ◽

Luís Carvalho ◽

Ricardo do Carmo ◽

...

Keyword(s):

Concrete Cover ◽

Time Dependent ◽

Sustainable Construction ◽

Cement Concrete ◽

Carbonation Resistance ◽

Shrinkage And Creep ◽

Binder Ratio ◽

Reference Curves ◽

Long Lifetime ◽

Formulation Parameters

The sustainability concerns of concrete construction are focused both on the materials’ eco-efficiency and on the structures’ durability. The present work focuses on the characterization of low cement concrete (LCC), regarding time-dependent and durability properties. LCC studies which explore the influence of the formulation parameters, such as the W/C (water/cement ratio), W/Ceq, (which represents the mass ratio between water and equivalent cement), W/B (water/binder) ratio, and the reference curves, on the aforementioned properties are limited. Thus, several LCC mixtures were formulated considering two dosages of binder powder, 350 and 250 kg/m3, the former with very plastic consistency and the latter with dry consistency, which were combined with a large spectrum of cement replacement rates (up to 70%), through adding fly ash and limestone filler, and with different compactness levels. The main objectives were to study the influence of the formulation parameters on the properties: shrinkage and creep, accelerated carbonation and water absorption, by capillarity, and by immersion. The lifetime of structures produced with the studied LCC was estimated, considering the durability performance, regarding the carbonation effect on the possible corrosion of the steel reinforcement. LCC mixtures with reduced cement dosage and high compactness, despite the high W/C ratios, have low shrinkage and those with higher strength have reduced creep, however depending on W/Ceq ratio. Those mixtures can be formulated and produced presenting good performance regarding carbonation resistance and, consequently, a long lifetime, which is mandatory for a sustainable construction. LCC with 175 kg/m3 of cement dosage is an example with higher lifetime than current concrete with 250 kg/m3 of cement; depending on the XC exposure classes (corrosion induced by carbonation), the amount of cement can be reduced between 37.5% and 42%, since the LCC with 175 kg/m3 of cement allows reducing the concrete cover below the minimum recommended, ensuring simultaneously the required lifetime for current and special structures.

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