Effect of Water-to-Cement Ratio on Cracking Resistance of Concrete at Early Age in Restrained Ring Specimens

2021 ◽  
Author(s):  
Dejian Shen ◽  
Yang Jiao ◽  
Ci Liu ◽  
Jiacheng Kang ◽  
Xiaojian Tang
Keyword(s):  
Development Rate ◽  
Ring Test ◽  
Engineering Practice ◽  
Early Age ◽  
Cracking Resistance ◽  
Multiple Parameters ◽  
Concrete Mixtures ◽  
Water To Cement Ratio ◽  
Study Results ◽  
The Impact

Nowadays, low water-to-cement (w/c) ratio has been put into widespread use in engineering practice. However, low w/c ratio may give rise to high self-desiccation, which may lead to the decrease of early-age cracking resistance. Investigating the impact of w/c ratio on cracking resistance is utterly meaningful to understand the cracking mechanism of concrete better. However, the corresponding investigations remain lacking, especially when the ring test is utilized. Ring tests for three concrete mixtures with different w/c ratios were conducted to investigate the early-age cracking resistance of concrete from multiple parameters in the present study. Results showed that: (1) the development rate of shrinkage of concrete for Mixture W50 was slower than Mixture W33 and W40; (2) the value and development rate of residual stress of concrete decreased when the w/c ratio increased; (3) the relaxed stress for all mixtures developed rapidly at very early age, and reached the maximum quickly; (4) the cracking resistance of concrete increased as the w/c ratio increased at early age.

The Research of GGBS’ Influence on the Cracking Resistance of Concrete

2014 ◽  
Vol 919-921 ◽  
pp. 1864-1867
Author(s):  
Yan Liu ◽  
Dao Xun Ma
Keyword(s):  
Test Method ◽  
Early Age ◽  
Cracking Resistance ◽  
Volume Stability ◽  
The Impact

The aim of this paper is to study the impact of GGBS on the early age cracking resistance of concrete. To assess the volume stability of premixed concrete under different dosage of GGBS an innovative cracking test method is adopted, and the causes and effect mechanisms of that are analyzed.

scholarly journals Soft Computing and Multi-Scal Model Technics to Predict the Early Age Compression Strength of Cement Paste as a Function of Polymer Contents, Water-to-Cement-Ratio, and Curing Ages

2021 ◽  
Author(s):  
Ahmed Mohammed ◽  
Kawan Ghafor ◽  
Wael Mahmood ◽  
Warzer Sarwar ◽  
Lajan Burhan
Keyword(s):  
Cement Paste ◽  
Compression Strength ◽  
Building Materials ◽  
Training Data ◽  
Early Age ◽  
Polymer Content ◽  
Data Set ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
The Impact

Abstract In this study, the effect of two water reducer polymers with smooth and rough surfaces on the compression strength of Ordinary Portland cement (OPC) was investigated. Three different initial ratios between water and cement (w/c) 0.5, 0.6, and 1 were used in this study. The amount of polymer contents varied from 0 to 0.06 % (%wt) for the cement paste with initial w/c of 0.5 and the polymer contents ranged between 0 to 0.16% (%wt) for the cement paste with initial w/c of 0.6 and 1 were investigated. SEM test was conducted to identify the impact of polymers on the behavior of cement paste. The compression strength of OPC cement was increased significantly with increasing the polymer contents. Because of a fiber net (netting) around cement paste particle was developed when the polymers were added to the cement paste which leads to decrease the void between the particles, binding the cement particles, therefore, increased the viscosity and compression strength of the cement rapidly. In this analysis, the hardness of cement paste with polymer contents has been evaluated and modeled using four different model technics. More environmentally sustainable construction, and lower cost than conventional building materials and early age strengths of the cement. To overcome the mentioned matter, this study aims to establish systematic multiscale models to predict the compression strength of cement paste containing polymers and to be used by the construction industry with no theoretical restrictions. For that purpose, a wide data a total of 280 tested cement paste modified with polymers, has been conducted, analyzed, and modeled. Linear, Nonlinear regression, M5P-tree, and Artificial Neural Network (ANN) technical approaches were used for the qualifications. In the modeling process, the most relevant parameters affecting the strength of cement paste, i.e. polymer incorporation ratio (0-0.16% of cement's mass), water-to-cement ratio (0.5-1), and curing ages (1 to 28 days). According to the correlation coefficient (R), mean absolute error and the root means a square error, the compression strength of cement paste can be well predicted in terms of w/c, polymer content, and curing time using four various simulation techniques. Among the used approaches and based on the training data set, the model made based on the Non-linear regression, ANN, and M5P-tree models seem to be the most reliable models. The sensitivity investigation concludes that the polymer content is the most dominating parameter for the prediction of the compression strength of cement paste with this data set.

Income Diversification and Bank Efficiency in Vietnam

2017 ◽  
pp. 52-67
Author(s):  
Sang Nguyen Minh
Keyword(s):  
Regression Model ◽  
Commercial Banks ◽  
Banking System ◽  
Operational Efficiency ◽  
Commercial Banking ◽  
Tobit Regression ◽  
Income Diversification ◽  
Positive Effects ◽  
Study Results ◽  
The Impact

This study uses the DEA (Data Envelopment Analysis) method to estimate the technical efficiency index of 34 Vietnamese commercial banks in the period 2007-2015, and then it analyzes the impact of income diversification on the operational efficiency of Vietnamese commercial banks through a censored regression model - the Tobit regression model. Research results indicate that income diversification has positive effects on the operational efficiency of Vietnamese commercial banks in the research period. Based on study results, in this research some recommendations forpolicy are given to enhance the operational efficiency of Vietnam’s commercial banking system.

Some reflections on social structure: Theoretical and practical aspects

2020 ◽  
Vol 18 (6) ◽  
pp. 1063-1078
Author(s):  
T.N. Skorobogatova ◽  
I.Yu. Marakhovskaya
Keyword(s):  
Service Industry ◽  
External Factors ◽  
Infrastructure Development ◽  
Social Infrastructure ◽  
Social Sphere ◽  
The Social ◽  
Study Results ◽  
The Republic ◽  
Internal And External Factors ◽  
The Impact

Subject. This article discusses the role of social infrastructure in the national economy and analyzes the relationship between the notions of Infrastructure, Service Industry and Non-Productive Sphere. Objectives. The article aims to outline a methodology for development of the social infrastructure of Russia's regions. Methods. For the study, we used the methods of statistical and comparative analyses. The Republic of Crimea and Rostov Oblast's social infrastructure development was considered as a case study. Results. The article finds that the level of social infrastructure is determined by a number of internal and external factors. By analyzing and assessing such factors, it is possible to develop promising areas for the social sphere advancement. Conclusions. Assessment and analysis of internal factors largely determined by the region's characteristics, as well as a comprehensive consideration of the impact of external factors will help ensure the competitiveness of the region's economy.

The Impact of Bar Service Operation Practices on Organizational Performance in Indian Hotel Industry

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohinder C. Dhiman ◽  
Abhishek Ghai
Keyword(s):  
Organizational Performance ◽  
Hotel Industry ◽  
Demographic Variables ◽  
Study Results ◽  
Service Operation ◽  
Managerial Implications ◽  
Overall Performance ◽  
The Impact ◽  
The Relationship ◽  
Bivariate Test

The paper has a two fold purpose - examine the impact of bar service operation practices (BSOP) on organizational performance (OP) and study the relationship between organizational performance and demographic variables. Based on a survey of 362 bar managers perceptions on the impact of bar service operation practices on organizational performance were assessed by 59 practices and 6 demographic variables. Bivariate test and ANOVA were employed to test the working hypothesis in the study. Results indicated that there is a positive relationship between the bar service operation practices and organizational performance. Further, the results indicate some practical and managerial implications to improve organizational overall performance.

scholarly journals Advances of 2nd Life Applications for Lithium Ion Batteries from Electric Vehicles Based on Energy Demand

2021 ◽  
Vol 13 (10) ◽  
pp. 5726
Author(s):  
Aleksandra Wewer ◽  
Pinar Bilge ◽  
Franz Dietrich
Keyword(s):  
Life Cycle ◽  
Lithium Ion Batteries ◽  
Electric Vehicles ◽  
Energy Demand ◽  
Lithium Ion ◽  
Life Cycles ◽  
Future Research ◽  
Research Areas ◽  
Study Results ◽  
The Impact

Electromobility is a new approach to the reduction of CO2 emissions and the deceleration of global warming. Its environmental impacts are often compared to traditional mobility solutions based on gasoline or diesel engines. The comparison pertains mostly to the single life cycle of a battery. The impact of multiple life cycles remains an important, and yet unanswered, question. The aim of this paper is to demonstrate advances of 2nd life applications for lithium ion batteries from electric vehicles based on their energy demand. Therefore, it highlights the limitations of a conventional life cycle analysis (LCA) and presents a supplementary method of analysis by providing the design and results of a meta study on the environmental impact of lithium ion batteries. The study focuses on energy demand, and investigates its total impact for different cases considering 2nd life applications such as (C1) material recycling, (C2) repurposing and (C3) reuse. Required reprocessing methods such as remanufacturing of batteries lie at the basis of these 2nd life applications. Batteries are used in their 2nd lives for stationary energy storage (C2, repurpose) and electric vehicles (C3, reuse). The study results confirm that both of these 2nd life applications require less energy than the recycling of batteries at the end of their first life and the production of new batteries. The paper concludes by identifying future research areas in order to generate precise forecasts for 2nd life applications and their industrial dissemination.

scholarly journals Robust Step Detection from Different Waist-Worn Sensor Positions: Implications for Clinical Studies

2020 ◽  
Vol 4 (1) ◽  
pp. 50-58
Author(s):  
Matthias  Tietsch ◽  
Amir Muaremi ◽  
Ieuan Clay ◽  
Felix Kluge ◽  
Holger Hoefling ◽  
...  
Keyword(s):  
Clinical Study ◽  
Clinical Studies ◽  
Neurological Diseases ◽  
Human Gait ◽  
Robust Solution ◽  
Step Detection ◽  
Study Protocols ◽  
Study Results ◽  
Wide Range ◽  
The Impact

Analyzing human gait with inertial sensors provides valuable insights into a wide range of health impairments, including many musculoskeletal and neurological diseases. A representative and reliable assessment of gait requires continuous monitoring over long periods and ideally takes place in the subjects’ habitual environment (real-world). An inconsistent sensor wearing position can affect gait characterization and influence clinical study results, thus clinical study protocols are typically highly proscriptive, instructing all participants to wear the sensor in a uniform manner. This restrictive approach improves data quality but reduces overall adherence. In this work, we analyze the impact of altering the sensor wearing position around the waist on sensor signal and step detection. We demonstrate that an asymmetrically worn sensor leads to additional odd-harmonic frequency components in the frequency spectrum. We propose a robust solution for step detection based on autocorrelation to overcome sensor position variation (sensitivity = 0.99, precision = 0.99). The proposed solution reduces the impact of inconsistent sensor positioning on gait characterization in clinical studies, thus providing more flexibility to protocol implementation and more freedom to participants to wear the sensor in the position most comfortable to them. This work is a first step towards truly position-agnostic gait assessment in clinical settings.

scholarly journals IMPACT OF LAPAROSCOPIC COLORECTAL SURGERY ON BODY IMAGE

2021 ◽  
Vol 108 (Supplement_3) ◽  
Author(s):  
A Fernández Candela ◽  
L Sánchez-Guillén ◽  
L García Catalá ◽  
C Curtis Martínez ◽  
M Bosch Ramírez ◽  
...  
Keyword(s):  
Body Image ◽  
Colorectal Surgery ◽  
Laparoscopic Colorectal Surgery ◽  
Wound Complication ◽  
Descriptive Study ◽  
Surgical Quality ◽  
Body Image Scale ◽  
Study Results ◽  
The Impact ◽  
Observational Descriptive Study

Abstract INTRODUCTION The aim of this study is to evaluate the impact of laparoscopic colorectal surgery (LCS) on body image using the validated Body Image Scale (BIS) as a parameter of surgical quality. MATERIAL AND METHODS We conducted an observational descriptive study. Patients who underwent scheduled LCS between June 2015 and December 2019 by a General Hospital Coloproctology Unit were included. RESULTS The sample included 180 patients, 115 men (63.9%) and 65 women (36.1%) with a median age of 67 years. Right hemicolectomies (31.7%) and sigmoidectomies (28.3%) were the main procedures performed. In most patients, a suprapubic (69.4%) or transverse (19.4%) incision was made. 21.9% suffered some type of postoperative complication (13.9% wound complication, 10.6% incisional hernia). The general result of the BIS questionnaire was satisfactory, with a median of 0 in the responses (no alteration of body image). We found that 46.2% of the women had some alteration in body image, compared to 28.7% of the men (p = 0.018) and low and ultra-low anterior resection were the surgeries that obtained worst scores, with 13,5% and 12,5% respectively of patients with a BIS score above 5 (p = 0.044). Patients with a stoma also obtained worst punctuation (25% above 5 vs 6,1%, p = 0.001). No statistically significant differences were found regarding type of incision, presence of complications and anxiety or depression. CONCLUSION Study results show, in general, good post-surgical body image after LCS. However, patients with stoma and women were more dissatisfied. Interestingly, there is no worse body image due to type of incision, so we recommend the least iatrogenic one.

scholarly journals Variation in performance on common content items at UK medical schools

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
David Hope ◽  
David Kluth ◽  
Matthew Homer ◽  
Avril Dewar ◽  
Richard Fuller ◽  
...  
Keyword(s):  
Undergraduate Students ◽  
Standard Setting ◽  
Medical Schools ◽  
Cross Sectional Study ◽  
Pass Rates ◽  
Cross Sectional ◽  
Study Results ◽  
Institutional Differences ◽  
Common Content ◽  
The Impact

Abstract Background Due to differing assessment systems across UK medical schools, making meaningful cross-school comparisons on undergraduate students’ performance in knowledge tests is difficult. Ahead of the introduction of a national licensing assessment in the UK, we evaluate schools’ performances on a shared pool of “common content” knowledge test items to compare candidates at different schools and evaluate whether they would pass under different standard setting regimes. Such information can then help develop a cross-school consensus on standard setting shared content. Methods We undertook a cross-sectional study in the academic sessions 2016-17 and 2017-18. Sixty “best of five” multiple choice ‘common content’ items were delivered each year, with five used in both years. In 2016-17 30 (of 31 eligible) medical schools undertook a mean of 52.6 items with 7,177 participants. In 2017-18 the same 30 medical schools undertook a mean of 52.8 items with 7,165 participants, creating a full sample of 14,342 medical students sitting common content prior to graduation. Using mean scores, we compared performance across items and carried out a “like-for-like” comparison of schools who used the same set of items then modelled the impact of different passing standards on these schools. Results Schools varied substantially on candidate total score. Schools differed in their performance with large (Cohen’s d around 1) effects. A passing standard that would see 5 % of candidates at high scoring schools fail left low-scoring schools with fail rates of up to 40 %, whereas a passing standard that would see 5 % of candidates at low scoring schools fail would see virtually no candidates from high scoring schools fail. Conclusions Candidates at different schools exhibited significant differences in scores in two separate sittings. Performance varied by enough that standards that produce realistic fail rates in one medical school may produce substantially different pass rates in other medical schools – despite identical content and the candidates being governed by the same regulator. Regardless of which hypothetical standards are “correct” as judged by experts, large institutional differences in pass rates must be explored and understood by medical educators before shared standards are applied. The study results can assist cross-school groups in developing a consensus on standard setting future licensing assessment.

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