Effect of fibres on early age cracking of concrete tunnel lining. Part I: Laboratory ring test

2016 ◽  
Vol 59 ◽  
pp. 215-220 ◽  
Author(s):  
M. Briffaut ◽  
F. Benboudjema ◽  
L. D’Aloia
Keyword(s):  
Tunnel Lining ◽  
Ring Test ◽  
Early Age

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.

Evaluation of Recycled Aggregate Concrete Cracking through Ring Test

2012 ◽  
Vol 174-177 ◽  
pp. 1475-1480 ◽  
Author(s):  
Valeria Corinaldesi ◽  
Giacomo Moriconi
Keyword(s):  
Numerical Models ◽  
Creep Behaviour ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Tensile Creep ◽  
Ring Test ◽  
Early Age ◽  
Concrete Aggregate ◽  
Free Shrinkage

Cracks can reduce the service life of a concrete structure by allowing aggressive agents to penetrate through it in easy ways. Free shrinkage evaluation alone is not enough to determine if cracking can be expected in a structure since concrete creep behaviour, stiffness and toughness also influence the potential for cracking. Consequently, it is rather interesting to perform restrained shrinkage tests, such as the ring test according to ASTM C 1581–04. The testing procedure involves concrete ring specimens restrained by an inner steel ring on which strain gauges are placed to determine the age of cracking, since abrupt changes in the steel strain occur when concrete is cracked. Both the ring test and free shrinkage test should be carried out in the same exposure conditions, 21°C and 50% relative humidity. Moreover, compressive and tensile strengths of concrete were evaluated on cubic specimens at the time of its cracking and up to 28 days of curing. By means of analytical and numerical models of the ring specimen, some useful information on the stress induced in the material and on the tensile creep behaviour of concrete can be extrapolated thus allowing to better interpret the experimental results. This experimental procedure enables to study the influence of concrete mixture composition on the potential for early-age cracking of concrete. In particular, in this work the influence on early-age cracking of recycled-concrete aggregate partially replacing virgin sand was tested.

An Evaluation on the Restrained Shrinkage of Ultra-High Performance Concrete

2012 ◽  
Vol 525-526 ◽  
pp. 449-452 ◽  
Author(s):  
Jung Jun Park ◽  
Doo Yeol Yoo ◽  
Sung Wook Kim ◽  
Young Soo Yoon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Tensile Creep ◽  
Ring Test ◽  
Early Age ◽  
Restrained Shrinkage ◽  
Reinforcing Bars ◽  
Ultra High Performance Concrete ◽  
Shrinkage Cracking ◽  
Coarse Aggregates

Since ultra-high performance concrete (UHPC) is subject to large occurrence of shrinkage at early age due to its low water-to-cement ratio, the mixing of large quantities of powdered admixtures and the absence of coarse aggregates, UHPC presents large risks of shrinkage cracking caused by the restraints provided by the form and reinforcing bars. Accordingly, this study intends to evaluate the shrinkage behavior of UHPC under restrained state by performing restrained shrinkage test using ring-test. The test results reveal that increasing thickness of the inner ring increases the tensile creep at early age leading to the reduction of the average strain and residual stress of the inner ring.

scholarly journals Evaluation of early age cracking in rendering mortars with polypropylene fibers

2018 ◽  
Vol 18 (2) ◽  
pp. 21-32
Author(s):  
Renata Monte ◽  
Mercia Maria Semensato Bottura Barros ◽  
Antonio Domingues de Figueiredo
Keyword(s):  
Crack Width ◽  
Hydrated Lime ◽  
Test Method ◽  
Ring Test ◽  
Early Age ◽  
Polypropylene Fibers ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Restrained Shrinkage Cracking ◽  
Fresh State

Abstract The incorporation of fibers in concrete produces an improvement in the characteristics of the material as observed in different studies. In order to obtain the same good results, fibers are added to rendering mortars to reduce some of their drawbacks. However, this type of mortar has some specific characteristics, such as hydrated-lime utilization or higher air, which is not usual in concrete. Thus, this study aims to evaluate the potential of polypropylene fibers to reduce early age cracking caused by restrained shrinkage in rendering mortars. Two types of mortars were used to verify possible differences in the way they responded to the introduction of fiber. The influence of the fiber content was also investigated. Mortars were evaluated in fresh state, and mechanical behaviors were measured at several ages. The restrained shrinkage cracking was followed for 21 days using the ring test method. The use of polypropylene fibers leads a smaller value of total crack width and a delay of the first crack. Also, the elastic modulus shows a higher correlation with the mortars crack width. Both parameters were successfully used to predict the mortars crack width. The ring test method may be a suitable test method to evaluate the capacity of fibers to control the crack formation in rendering mortars.

Determination of Tensile Creep and Stress Relaxation of Concrete by Ring Test

2014 ◽  
Vol 584-586 ◽  
pp. 1172-1175
Author(s):  
Si Chen Li ◽  
Ting Yao ◽  
Yu Jiang Wang ◽  
Hua Li ◽  
Jun Cheng ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Testing Machine ◽  
Tensile Creep ◽  
Ring Test ◽  
Shrinkage Stress ◽  
Early Age ◽  
Free Shrinkage ◽  
Binder Ratio ◽  
Creep And Stress Relaxation ◽  
Accurate Stress Analysis

The understanding of stress relaxation and tensile creep behavior is extremely important in accurate stress analysis and crack prediction of early-age concrete. The free shrinkage deformations of concrete with different strength grade were examined. The early-age tensile elastic modulus of concrete was investigated through temperature-stress testing machine. The tensile creep and shrinkage stress were obtained through the modified restrained ring test. The results indicate that the development of free shrinkage coordinates well with the inner strain of steel ring. Tensile creep decreases as water-binder ratio increases. Creep counteracts tensile stress of concrete by 28%~40% , decreases the possibility of cracking of concrete at early ages.

Quantifying Early-Age Stress Development and Cracking in Low Water-to-Cement Concrete: Restrained-Ring Test with Acoustic Emission

2003 ◽  
Vol 1834 (1) ◽  
pp. 24-32 ◽  
Author(s):  
Akhter B. Hossain ◽  
Brad Pease ◽  
Jason Weiss
Keyword(s):  
Acoustic Emission ◽  
Stress Relaxation ◽  
Length Change ◽  
Ring Test ◽  
Early Age ◽  
Free Shrinkage ◽  
Stress Development ◽  
Complex Interactions ◽  
Degree Of Restraint ◽  
Restrained Ring Test

Early-age cracking has been found to occur in some concrete bridge decks, slabs, and pavements when the volumetric changes associated with drying, hydration, and temperature reduction are prevented. While free-shrinkage tests can quantify length change, they may not always be sufficient for detecting materials that are prone to cracking, since the potential for cracking is influenced by complex interactions of strength gain, stiffness development, creep, shrinkage, the degree of restraint, and toughness. The simplicity of the ring test enables it to be used as a comparative test to screen potential mixture designs. From the use of this test, AASHTO developed a provisional standard ring test that establishes specimen geometry; however, the provisional standard does not provide an approach for quantifying stress development or indicating how close a specimen may be to failure. Described is a simple stress solution for quantifying the results of the ring test. Issues related to ring and free-shrinkage specimen geometries are discussed to improve the fundamental understanding of the information provided by the ring test. Also described is how elastic stress and actual stress can be compared to measure the stress relaxation in a material. To better illustrate the microcracking and visible-crack development process, acoustic-emission testing was performed. These experiments indicated that specimens with a higher level of restraint exhibited more microcracking as a part of the stress relaxation process.

Sign in / Sign up

Export Citation Format

Share Document