scholarly journals Research on Deterioration Mechanism of Concrete Materials in an Actual Structure

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Shiping Zhang ◽  
Xiang Dong ◽  
Houxian Zhang ◽  
Min Deng
Keyword(s):  
Concrete Structure ◽  
Frost Resistance ◽  
Field Survey ◽  
Petrographic Analysis ◽  
Actual Structure ◽  
Freeze Thaw ◽  
Alkali Aggregate Reaction ◽  
Deterioration Mechanism ◽  
Concrete Materials

The cause for deterioration of the concrete structure located in severe environment has been explored both in field and in laboratory. Serious cracking and spalling appeared upon surface of the concrete structure soon after the structure was put into service. Both alkali-aggregate reaction and freeze-thaw cycles may result in similar macro visible cracking and spalling. The possibility of alkali-aggregate reaction was excluded by both field survey and lab examination such as chemical analysis, petrographic analysis, and determination of alkali reactivity of aggregates. According to results of freeze-thaw cycles, impermeability testing, and microstructure analysis, it is deduced that the severe environmental conditions plus the relatively inferior frost resistance cause the deterioration of concrete. Usage of air entraining admixture can improve frost resistance and impermeability. Furthermore, new approaches to mitigate the deterioration of concrete used in severe environmental condition are discussed.

Effect of Steel Fiber on Comprehensive Performance of Concrete Materials

2015 ◽  
Vol 723 ◽  
pp. 440-444
Author(s):  
Liang Feng Dong ◽  
Shi Ping Zhang
Keyword(s):  
Flexural Strength ◽  
Frost Resistance ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Freeze Thaw ◽  
Comprehensive Performance ◽  
Concrete Materials ◽  
Compressive And Flexural Strengths

This paper presents the results on the influence of steel fiber on the performance of concrete materials. The performance of steel fiber reinforced concrete was studied through mechanical testing, frost resistance, carbonation and impermeability testing. Experimental results showed that steel fibers can improve compressive and flexural strengths, and especially can significantly improve flexural strength. Frost resistance can also be improved, and the higher the volume of steel fibers added, the more the freeze-thaw cycles that concrete could resist. Furthermore, steel fiber can not only slow down the carbonation rate indirectly, but also improve the impermeability of concrete, and impermeability enhanced with the increase of steel fiber.

Dependence of Relative Decreasing in Strength by Rate of Strain for the New Rapid Method for Determination of Concrete Frost Resistance

2015 ◽  
Vol 725-726 ◽  
pp. 505-510
Author(s):  
Olga Pertseva ◽  
Sergey Nikolskiy
Keyword(s):  
Tensile Strength ◽  
Rapid Method ◽  
Frost Resistance ◽  
New Method ◽  
Basic Method ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Freezing And Thawing Cycles ◽  
Non Destructive

The task of the project is obtaining the dependence between the relative decreasing of strength and rate of strain and substantiation of the new method for determination of concrete frost resistance. It has been analytically proved that using concrete’s rate of strain ε as a measure of damage, instead of decreasing of tensile strength R, increases freeze-thaw resistance’s accuracy of estimation a lot under otherwise equal conditions by the time of freeze-thaw cycling. Also it has been experimentally shown that ratio of relative decreasing R to ε in direction, perpendicular to compression, is assumed to be independent on values R and ε for a given concrete and on the ways of achieving them during mechanical or freeze-thaw cycling. To determine the dependence δR/R by ε (z) 8 specimens were tested by non-destructive method (RU 2 490 631) and two baths of 50 specimens by basic method (thermo cycling). Results of the non-destructive method are different from results by basic method for 6,3%. Dependence of relative decreasing in strength by rate of strain is near to linear and, therefore, value of z is constant. Taking this into account patented methods for estimation of concrete’s freeze-thaw resistance as per values R and ε received after freezing and thawing cycles of some specimens and their postlimenary failure by linear compression was substantiated.

Bestimmung der Dauerhaftigkeit von Hochleistungsbeton mit Hilfe des CDF-Tests / Determination of the durability of high performance concrete by means of CDF-test

1999 ◽  
Vol 5 (1) ◽  
pp. 29-40
Author(s):  
R. Krumbach ◽  
U. Schmelter ◽  
K. Seyfarth
Keyword(s):  
Frost Resistance ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Strength Concrete ◽  
Factors Influencing

Abstract Variable obsen>ations concerning frost resistance of high performance concrete have been made. The question arises which are the decisive factors influencing durability under the action of frost and de-icing salt. The proposed experiments are to be carried out in cooperation with F.A.- Finger - Institute of Bauhaus University Weimar. The aim of this study is to determine possible change of durability of high strength concrete, and to investigate the origin thereof. Measures to reduce the risk of reduced durability have to be found.

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

Optimization Research of Mix Proportion of Frost Resistance Construction of Concrete Based on the MATLAB Language

2014 ◽  
Vol 584-586 ◽  
pp. 1917-1921
Author(s):  
Jun Jie Zhang ◽  
Rui Hong Shao ◽  
Xiang Yi Meng
Keyword(s):  
Compressive Strength ◽  
Objective Function ◽  
Frost Resistance ◽  
Unit Volume ◽  
Influence Factors ◽  
Multi Objective Optimization ◽  
Cold Region ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Mix Proportion

Analyze the influence factors of mix proportion affecting concrete freeze-thaw damage. Use the five main performance indexes of the concrete, which are compressive strength, strength of extension, impermeability grade, and frost resistance grade and per unit volume cost concrete, as the objective function of multi-objective optimization equation. Invoke the fgoalattain function in the MATLAB Optimization Toolbox to solve. The optimized parameters of mix proportion of frost resistance construction of unit concrete in cold region are: concrete 1532.6kg, water 910kg, sand 5510.6kg, 5-20mm cobblestone 3747.2kg、20-40mm cobblestone 3658.6kg、40-80mm cobblestone 4733.5kg、80-150mm cobblestone 4738.1kg, and the dosage of water reducing agent is 7.3kg.

Measurement of progesterone in sheep using a commercial ELISA kit for human plasma

2021 ◽  
pp. 104063872110435
Author(s):  
Valeria Pasciu ◽  
Maria Nieddu ◽  
Elena Baralla ◽  
Cristian Porcu ◽  
Francesca Sotgiu ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Human Plasma ◽  
Method Validation ◽  
Plasma Progesterone ◽  
Freeze Thaw ◽  
Elisa Kit ◽  
Stability Data ◽  
Human Use ◽  
Species Specific

Determination of serum or plasma progesterone (P4) concentrations is important to recognize pregnant and non-pregnant ewes, and also to predict the number of carried lambs. The 2 most common methodologies for the detection of plasma P4 are radioimmunoassay (RIA) and enzyme immunoassay (EIA). RIA is very expensive, and not all laboratories are equipped to perform this test; EIA is commercially available for human use, but only a few companies produce species-specific kits, which are expensive. We verified for ovine plasma a less expensive and easily available ELISA kit (DiaMetra) designed to quantify P4 in humans. Pools of ovine and human plasma were used to compare repeatability, accuracy, sensitivity, and stability of P4 measured by the DiaMetra kit. Repeatability data were within 15%, and accuracy values were ~90% for both plasma matrices. Stability data showed a loss of <20% for freeze–thaw and <30% for 30-d storage. All parameters were acceptable under international guidelines for method validation. The human ELISA kit was used successfully to quantify plasma P4 in 26 ewes during pregnancy until delivery. P4 concentrations were also correlated with the number of carried lambs.

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