scholarly journals Tensile Creep Model of Slab Concrete Based on Microprestress-Solidification Theory

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3157
Author(s):  
Zhifang Zhao ◽  
Huanmi Zhang ◽  
Bo Fang ◽  
Yukun Sun ◽  
Yangfeng Zhong ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Testing Machine ◽  
Tensile Creep ◽  
Creep Model ◽  
Temperature Deformation ◽  
Early Age ◽  
Cracking Resistance ◽  
Kelvin Model ◽  
Mgo Concrete ◽  
Better Than

Tensile creep is an important factor affecting the early cracking resistance of concrete. The tensile creep model can effectively predict the development of tensile creep. In order to establish an appropriate tensile creep model, a temperature–stress testing machine (TSTM) was employed to test the development of temperature, deformation and restraint stress of benchmark concrete and concrete mixed with the MgO under different temperature curing modes. The development law of early age stress, strain and creep was analyzed via the test data of the TSTM. The early age tensile creep of concrete was predicted with the existing Kelvin creep model. The effect of variable temperature on creep was considered in this study, and an improved Kelvin creep model was proposed. The prediction accuracy of the two models was compared and analyzed. The results indicate that MgO has little influence on the creep and specific creep of concrete. The early age cracking resistance of MgO concrete is better than benchmark concrete. The improved Kelvin model based on the microprestress-solidification (MPS) theory predicts the early tensile creep of concrete more accurately in variable temperature conditions. These are significantly helpful for the application of the MgO expansion agent in dam engineering.

Influence of Aggregates on Cracking Resistance of Concrete at Early Age

2012 ◽  
Vol 151 ◽  
pp. 474-479
Author(s):  
Bo Chen ◽  
Jian Tong Ding ◽  
Yue Bo Cai
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
Stress Testing ◽  
Testing Machine ◽  
Tensile Creep ◽  
Early Age ◽  
Test Results ◽  
Cracking Resistance ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

In order to investigate influence of aggregates on cracking resistance of concrete at early age, four kinds of aggregates, i.e. syenite, basalt, marble and sandstone, were used for the test on cracking resistance of hydraulic concretes by the temperature stress testing machine. Analogy analysis was carried out with test results of concretes with two gradings of aggregates. The results show that aggregates affect elastic modulus, thermal expansion coefficients and tensile creep behavior of concrete at early age. However, the temperature rise of concrete was slightly affected by various types and gradings of aggregate. Moreover, the cracking temperature is reliably to be used to quantitatively evaluate the influence of aggregates on cracking resistance of concrete at early age.

scholarly journals Study on the Tensile Creep Model of the Admixture of Early-Age Concrete and Application Simulation

2015 ◽  
Vol 9 (1) ◽  
pp. 1002-1006 ◽  
Author(s):  
Qin Keli ◽  
Duan Yajuan ◽  
Guo Lixia
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Reference Model ◽  
Polypropylene Fiber ◽  
Model Fitting ◽  
Tensile Creep ◽  
Creep Model ◽  
Early Age ◽  
Concrete Creep ◽  
Factor C

With respect to the recent issue related to the lack of research on tensile creep model of the admixture concrete at early age and simulation, the admixture influence function with factor of the admixture dosage was established based on composite exponential function as reference model based on existed creep rules and appropriate assumption. It has been proposed that contributing factor, c, quantitatively represented the sensitivity of concrete creep changes to the admixture and correlation between concrete creep and the admixture. The model fitting was then made after tensile creep experiment by adding different admixtures such as fly ash, slag, silica fume and polypropylene fiber in contract to reference concrete test. It indicated that the model exhibited a good fitting performance, which is practical and useful as well as readily adopted by simulation. Meanwhile, the contributing factor also demonstrated quantitatively the variation among the effect of the admixtures (fly ash, slag, silica fume and polypropylene fiber) on the tensile creep of the concrete. Finally, the model was applied to an as-built concrete project for extended simulation, the results indicated that tensile creep can effectively improve the distribution of surface tensile stress and alleviate detrimental effect due to day-night temperature differences.

The Effects of Water-Reducer on Early-Age Plastic Shrinkage of Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 1113-1118
Author(s):  
Hong Gen Qin ◽  
Zhi Hua Fei ◽  
Wei Guo ◽  
Qian Tian
Keyword(s):  
Capillary Pressure ◽  
Evaporation Rate ◽  
Mechanical Performance ◽  
Important Influence ◽  
Early Age ◽  
Cracking Resistance ◽  
Plastic Shrinkage ◽  
Effect Of Water ◽  
Better Than

Water-reducer is one of the dispensable components in modern concrete, can improve the workability and mechanical performance of concrete, and also has an important influence on the plastic cracking resistance of concrete. In this paper, the flat cracking test was used to evaluate the effect of water reducer on the plastic cracking resistance of concrete, meanwhile, capillary pressure; plastic settlement and evaporation rate were also tested. The results showed that water-reducer could improve the plastic cracking resistance of concrete significantly, and the effectiveness of polycarboxylate water reducer were o better than that of wood calcium and naphthalene water reducer.

Tensile creep and cracking resistance of concrete with different water-to-cement ratios at early age

2017 ◽  
Vol 146 ◽  
pp. 410-418 ◽  
Author(s):  
Dejian Shen ◽  
Jinliang Jiang ◽  
Wenting Wang ◽  
Jiaxin Shen ◽  
Guoqing Jiang
Keyword(s):  
Tensile Creep ◽  
Early Age ◽  
Cracking Resistance

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.

scholarly journals Study on creep performance of launch canister under long-term storage

2019 ◽  
Vol 43 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Cun-Gui Yu ◽  
Tong-Sheng Sun ◽  
Guang-Yuan Xiao
Keyword(s):  
Residual Deformation ◽  
Bottom Layer ◽  
Tensile Creep ◽  
Creep Model ◽  
Model Parameters ◽  
Creep Tests ◽  
Software Environment ◽  
Long Term Storage ◽  
Term Storage

In this paper, the creep performance of a multi-barrel rocket launch canister under long-term stacking storage is studied. Based on the Bailey–Norton model, a creep model for the frame material of a launch canister was established. Constant stress tensile creep tests under different stress levels at room temperature were carried out on the frame materials of the launch canister and the creep model parameters were obtained by test data fitting. The three-dimensional finite element model of the launch canister was established in the ABAQUS software environment and the creep deformation of the launch canister after long-term stacking storage was studied. The results indicated that the bottom layer of the launch canister frame presented an extended residual deformation when the stacking storage solution with the original support pad was used. Therefore, a position adjustment program of the support pad was put forward. The residual deformation of the launch canister frame after long-term storage could be significantly reduced, thus the performance requirements for the launch canister are guaranteed.

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