Study on durability of non-dispersible concrete in seawater environment

2019 ◽  
Vol 11 (3) ◽  
pp. 443-452
Author(s):  
Wu Huijun ◽  
Zhan Diao ◽  
Kaizuo Fan
Keyword(s):  
Chloride Ion ◽  
Mineral Admixtures ◽  
Engineering Practice ◽  
Durability Test ◽  
Test Analysis ◽  
Content Type ◽  
Concrete Mixtures ◽  
Seawater Environment ◽  
Underwater Concrete ◽  
Durability Of Concrete

Purpose The purpose of this paper is to focus on the durability of underwater non-dispersible concrete in seawater environment. Design/methodology/approach In this paper, ten groups of underwater non-dispersible concrete mixtures were designed, and the anti-dispersibility and fluidity of the mixtures were tested. Findings The durability test analysis shows that different pouring methods have different effects on the durability of concrete. The durability of concrete poured on land is better than that poured in water. Different mineral admixtures have different effects on the durability of concrete: the frost resistance of the underwater non-dispersible concrete specimens with silica fume is the best; the impermeability and chloride ion permeability of the non-dispersible underwater concrete specimens with waterproofing agent are the best; and the alternation of wetting and drying has adverse effects on the durability indexes of the non-dispersible underwater concrete. Originality/value The durability of underwater non-dispersible concrete is tested and the results can be used for reference in engineering practice.

Study on mechanical properties of non-dispersible concrete in seawater environment

2019 ◽  
Vol 11 (6) ◽  
pp. 809-818
Author(s):  
Huijun Wu
Keyword(s):  
Mechanical Properties ◽  
Design Methodology ◽  
New Products ◽  
Main Approach ◽  
Content Type ◽  
Concrete Mixtures ◽  
Seawater Environment ◽  
Hardened Properties ◽  
Underwater Concrete ◽  
Working Performance

Purpose The purpose of this paper is to research the hardened properties of non-dispersible concrete in seawater environment, especially in seawater environment. Design/methodology/approach The main approach is according to the experiment. Findings The findings of this paper are: first, because of the washing effect of water, the strength of underwater non-dispersible concrete is lower than that of terrestrial concrete. Second, the strength of non-dispersible underwater concrete with silica fume increases remarkably at different ages. Third, underwater non-dispersible concrete does not produce new products when it is formed and cured in seawater. Originality/value In this paper, underwater non-dispersible concrete is formed and maintained on land, freshwater and seawater by underwater pouring method. The working performance, mechanical properties and durability of underwater non-dispersible concrete mixtures after hardening are tested.

A study of a real-time online monitoring system for the durability of concrete structures

2016 ◽  
Vol 63 (3) ◽  
pp. 184-189
Author(s):  
Mingming Xiao ◽  
Shilong Zhang ◽  
Yanbing Tang ◽  
Zhongmao Lin ◽  
Jiahong Chen
Keyword(s):  
Real Time ◽  
Monitoring System ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Corrosion Current ◽  
Ion Concentration ◽  
Corrosion Monitoring ◽  
Content Type ◽  
System Data ◽  
Durability Of Concrete

Purpose This study aims to explore the effect of corrosion monitoring technology for ensuring concrete structure safety. Design/methodology/approach A new monitoring system scheme with unattended operation to evaluate the durability of concrete structures is presented, which includes four components, namely, a multi-function embedded sensor, a microprocessor data collecting module, a system data analysis and storage module, and a remote server module. Findings The system carries out monitoring of chloride ion concentration and pH in concrete, corrosion current density and of the self-corrosion potential of the reinforcing steel bar. Originality/value This system provides real-time, online, lossless monitoring for concrete structures.

Effect of Mineral Admixtures on Durability of Concrete Structure Subjected to Alkaline Saline Corrosions

2006 ◽  
Vol 302-303 ◽  
pp. 68-72
Author(s):  
Quan Lin Niu ◽  
Nai Qian Feng
Keyword(s):  
Chloride Ion ◽  
Sulfate Attack ◽  
Mineral Admixtures ◽  
Alkali Silica Reaction ◽  
Sulfate Ion ◽  
Diffusion Test ◽  
Alkali Ions ◽  
Furnace Slag ◽  
Drying Test ◽  
Durability Of Concrete

Effect of a combination of alkali ions, sulfate ion and chloride ion on durability of concrete structures was analyzed, and the effect of different mineral admixtures on deterioration caused by Cl- penetration, sulfate attack and alkali-silica reaction was investigated. It is shown from wetting-drying test that sulfate attack on concrete was greatly relieved in high Cl- concentration solution, but diffusion test showed that Cl- diffusion was accelerated by SO4 2- ion existence as SO4 2- may incorporate with aluminum phase prior to Cl- ion. Replacement of cement with mineral admixtures such as ground blast furnace slag (SL) and metalaolin (MK) were beneficial for absorption of Cl- ion penetrated into paste, while ASTM C441 showed that fly ash (FA), metakaolin and natural zeolite (NZ) exhibited effectiveness in controlling Alkali-silica reaction (ASR).

A review on visual criteria of pure milk packaging for parents and their children (case study: Tehran, Iran)

2016 ◽  
Vol 118 (1) ◽  
pp. 83-99 ◽  
Author(s):  
Mohsen Rasouli Valajoozi ◽  
Nosrat Ollah Zangi
Keyword(s):  
Influential Factors ◽  
Test Analysis ◽  
Content Type ◽  
Packaging Design ◽  
Parents And Children ◽  
Children And Parents ◽  
The Aesthetic ◽  
Pure Milk ◽  
Practical Recommendations

Purpose – The purpose of this paper is to compare and find the significance of aesthetic standards related to the packaging design of pure milk among two groups of parents and children in order to help the designers and marketers to identify these two groups of consumers well. Design/methodology/approach – The results of questionnaire were used to get the required data. The selected samples were divided into two groups of 110 parents and children aged between seven and 14 years old who responded to the questions. The subjects were compared and evaluated within the convenience stores in the cosmopolitan city of Tehran based on four independent variables as the influential factors in packaging attractiveness. Data were analyzed through the statistical analysis software using the Independent t-test analysis. Findings – The results of analysis showed that all the variables vary significantly among these two groups. Besides, the importance and priority of variables were determined for each group based on the mean score of each variable. Originality/value – According to the results of this study, it could be concluded that the selection criteria and packaging attractiveness varies among children and parents, and the aesthetic factors of packaging could be used with different priorities for these two groups. And also at the end of research some practical recommendations are presented in order of importance based on parents’ preferences.

Permeability of Lightweight Aggregate Concrete with Mineral Admixture

2013 ◽  
Vol 857 ◽  
pp. 105-109
Author(s):  
Xiu Hua Zheng ◽  
Shu Jie Song ◽  
Yong Quan Zhang
Keyword(s):  
Pore Structure ◽  
Lightweight Concrete ◽  
Chloride Ion ◽  
Lightweight Aggregate ◽  
Total Porosity ◽  
Normal Weight ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete

This paper presents an experimental study on the permeability and the pore structure of lightweight concrete with fly ash, zeolite powder, or silica fume, in comparison to that of normal weight aggregate concrete. The results showed that the mineral admixtures can improve the anti-permeability performance of lightweight aggregate concrete, and mixed with compound mineral admixtures further more. The resistance to chloride-ion permeability of light weight concrete was higher than that of At the same strength grade, the anti-permeability performance of lightweight aggregate concrete is better than that of normal weight aggregate concrete. The anti-permeability performance of LC40 was similar to that of C60. Mineral admixtures can obviously improve the pore structure of lightweight aggregate concrete, the total porosity reduced while the pore size decreased.

Differential blockade of cat dorsal root C fibers by various chloride solutions

1972 ◽  
Vol 36 (5) ◽  
pp. 569-583 ◽  
Author(s):  
J. Stovall King ◽  
Don L. Jewett ◽  
Howard R. Sundberg
Keyword(s):  
Hypertonic Saline ◽  
Choline Chloride ◽  
Isotonic Saline ◽  
Chloride Ion ◽  
Content Type ◽  
Persistent Effect ◽  
C Fibers ◽  
C Fiber ◽  
Intrathecal Infusion

✓ A possible mechanism by which intrathecal infusion of partially frozen saline might relieve patients of chronic pain has been studied by applying hypertonic saline to the dorsal rootlets of cats in vitro. The supernatant of partially thawed normal saline was found to be hypertonic. Persistent block of C fibers, detected by a collision method, occurred after the rootlets had been exposed to saline from 500 to 2500 mOsm/L for 15 min followed by 15 min of isotonic saline. Few of the A fibers were blocked by this procedure, but both A and C fibers were blocked when solutions of 3500 mOsm/L were used. Differential blockage of C fibers could also be produced with hypotonic saline and with distilled water. Localized cooling, to 2°C for 25 min, had no persistent effect on C fiber conduction, and when cooling was combined with hypertonic saline there was no potentiation of the differential blockade caused by the saline. Hypertonic solutions of sucrose or sodium nitrate produced no persistent differential block; most A and C fibers recovered. However, choline chloride was as effective as sodium chloride in giving a differential blockade. It seems that chloride ion plays a major role in establishing the persistent C fiber blockade observed when dorsal rootlets are exposed to hypertonic saline.

scholarly journals Influence of Steam Curing Method on the Performance of Concrete Containing a Large Portion of Mineral Admixtures

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Mengyuan Li ◽  
Qiang Wang ◽  
Jun Yang
Keyword(s):  
Chloride Ion ◽  
Mineral Admixtures ◽  
Strength Development ◽  
Steam Curing ◽  
Chloride Permeability ◽  
Curing Conditions ◽  
Volume Stability ◽  
Ettringite Formation ◽  
The Impact ◽  
Reaction Degree

A comparison was made between the impact of raising the thermostatic temperature and the impact of prolonging the thermostatic time on the performance of steam-cured concrete containing a large portion of fly ash (FA) or ground granulated blast furnace slag (GGBS) by analysing the form removal strength, chemically combined water content, reaction degree, strength development, chloride permeability, and volume stability. For the materials and test conditions reported in this study, raising the thermostatic temperature is more favourable for concrete containing FA, as indicated by the significantly higher form removal strength and the higher growth of reaction degree of FA compared with prolonging the thermostatic time. With an increase in the thermostatic temperature, the hydration degree of a binder containing FA or GGBS initially increases and subsequently decreases. Although concrete containing FA can obtain satisfactory form removal strength with steam curing at 80°C, the late strength development of concrete containing FA is slow for the same curing conditions. The effect of the late performance of resistance to chloride ion permeability improved by FA is better than the effect improved by GGBS. The risk of destroying the structure of concrete containing a large portion of FA or GGBS due to delayed ettringite formation (DEF) is minimal when specimens were steam-cured at 80°C.

Career choice of real estate students in Nigeria

2019 ◽  
Vol 37 (1) ◽  
pp. 154-176 ◽  
Author(s):  
Timothy Oluwafemi Ayodele
Keyword(s):  
Real Estate ◽  
Career Choice ◽  
Third Party ◽  
Southwestern Nigeria ◽  
Test Analysis ◽  
Content Type ◽  
The Real Estate ◽  
Factors Influencing ◽  
Real Estate Sector ◽  
Career Preferences

Purpose The purpose of this paper is to examine the career preferences of real estate students and the predisposing factors influencing the choice of career. The study also analysed the gender and socioeconomic variations with respect to the career preferences and factors influencing the career choice of real estate students in an emergent market like Nigeria. Design/methodology/approach Closed-ended questionnaires were administered on final year real estate students in the three Federal universities offering real estate in Southwestern Nigeria. Data were analysed using frequency counts, percentages, mean ranking, independent t-test, analysis of variance and correlation analysis. Findings The findings showed that the predominant individual factors influencing career choice of real estate students were personal career interest, the magnitude of initial salary, future financial prospects and job security. Furthermore, while intrinsic and economic/financial factors were the major themes influencing respondents’ career choice, the influence of a third party was less a likely determinant. Analysis of gender differences showed that there was a statistical difference between the male and female respondents with respect to the intrinsic and career exposure factors. Research limitations/implications The study has implications for real estate students, career advisers/academic counsellors, organisations employing the services of real estate graduates, and educational institutions and policy stakeholders in the real estate sector. The study also has implication for real estate professional bodies in Nigeria and other emergent markets. Originality/value This is perhaps the first attempt that examined the factors influencing the career choice of real estate students in an emergent market like Nigeria, especially from the perspectives of gender and socioeconomic variations.

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