Shrinkage and Cracking Behavior of Cement Based Materials Containing Undercalcined MgO-Based Expansive Agent

2013 ◽  
Vol 357-360 ◽  
pp. 1148-1153
Author(s):  
Shou Zhi Zhang ◽  
Qian Tian ◽  
Ting Yao ◽  
Fei Guo
Keyword(s):  
Drying Shrinkage ◽  
Length Change ◽  
Experimental Results ◽  
Shrinkage Cracking ◽  
Cracking Behavior ◽  
Expansive Agent ◽  
Restrained Condition ◽  
Cement Based Materials ◽  
Single Ring ◽  
Drying Condition

This paper gives a comprehensive investigation on the effects of undercalcined MgO-based expansive agent (UMEA) on the shrinkage and associated cracking behavior of cement based materials, including length change under drying condition and restrained condition, and cracking under single-ring restraint. Experimental results showed that the UMEA could reduce the drying shrinkage as well as restrained shrinkage of cement based materials effectively. The measured shrinkage reduction was up to 55.3% at the age of 180d of drying. It was also found that the addition of shrinkage could effectively improve the shrinkage cracking resistance of cement based materials even under drying condition. The experimental results of autoclaving testing showed that the UMEA has a larger dosage of stability. If the dosage in cement is controlled according to the requirement of concrete construction, the UMEA can be used to compensate the shrinkage as designed.

Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
The Other ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Compressive Properties ◽  
Shrinkage Cracking ◽  
Steel Fibre Reinforced Concrete ◽  
Expansive Agent ◽  
Concrete Matrix

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

Multiaxial Fatigue of 16MnR Steel

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Zengliang Gao ◽  
Tianwen Zhao ◽  
Xiaogui Wang ◽  
Yanyao Jiang
Keyword(s):  
Pure Shear ◽  
Ambient Air ◽  
Shear Loading ◽  
Multiaxial Fatigue ◽  
Experimental Results ◽  
Pressure Vessel Steel ◽  
Critical Plane ◽  
Cracking Behavior ◽  
Vessel Steel ◽  
Axial Torsion

Uniaxial, torsion, and axial-torsion fatigue experiments were conducted on a pressure vessel steel, 16MnR, in ambient air. The uniaxial experiments were conducted using solid cylindrical specimens. Axial-torsion experiments employed thin-walled tubular specimens subjected to proportional and nonproportional loading. The true fracture stress and strain were obtained by testing solid shafts under monotonic torsion. Experimental results reveal that the material under investigation does not display significant nonproportional hardening. The material was found to display shear cracking under pure shear loading but tensile cracking under tension-compression loading. Two critical plane multiaxial fatigue criteria, namely, the Fatemi–Socie criterion and the Jiang criterion, were evaluated based on the experimental results. The Fatemi–Socie criterion combines the maximum shear strain amplitude with a consideration of the normal stress on the critical plane. The Jiang criterion makes use of the plastic strain energy on a material plane as the major contributor to the fatigue damage. Both criteria were found to correlate well with the experiments in terms of fatigue life. The predicted cracking directions by the criteria were less satisfactory when comparing with the experimentally observed cracking behavior under different loading conditions.

scholarly journals STUDY ON DRYING SHRINKAGE CRACKING PROPERTIES OF FLY ASH MORTAR UNDER DIFFERENT DRYING CONDITIONS

2017 ◽  
Vol 71 (1) ◽  
pp. 386-393
Author(s):  
Satoshi YOSHIKAWA ◽  
Yoshiaki SATO ◽  
Toshihiro OTANI ◽  
Kenji UEDA
Keyword(s):  
Fly Ash ◽  
Drying Shrinkage ◽  
Shrinkage Cracking ◽  
Drying Conditions

Control of Cracking with Shrinkage-Reducing Admixtures

1997 ◽  
Vol 1574 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Surendra P. Shah ◽  
Shashidhara Marikunte ◽  
Wei Yang ◽  
Corina Aldea
Keyword(s):  
Drying Shrinkage ◽  
Plain Concrete ◽  
Type Specimen ◽  
Wire Mesh ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Restrained Shrinkage Cracking ◽  
Tensile Forces ◽  
Parking Garages ◽  
Shrinkage Reducing Admixtures

Shrinkage cracking can be a critical problem in concrete construction, especially for flat structures such as highway pavements, slabs for parking garages, and bridge decks. One way to reduce the shrinkage cracking is to provide reinforcement in the form of wire mesh to resist tensile forces. In recent years, short, randomly distributed fibers have been used to control shrinkage cracking. The efficiency of shrinkage-reducing admixtures (SRAs) in controlling restrained shrinkage cracking of concrete is reviewed. A ring-type specimen was used for restrained shrinkage cracking tests. The SRA selected for this investigation was a propylene glycol derivative, which was used at 1 and 2 percent by weight of cement. Free (unrestrained) shrinkage, weight loss, compressive strength, and fracture toughness were also investigated. The results of SRA concretes were compared with that of plain concrete with the same water-to-cement ratio. A theoretical model based on nonlinear fracture mechanics was developed for predicting transverse cracking of the concrete ring specimen caused by drying shrinkage. The model prediction of time to cracking compared well with the experimental data. The model can be extended to different geometries and dimensions than those considered in this research.

Drying shrinkage cracking of concrete using dune sand and crushed sand

2016 ◽  
Vol 126 ◽  
pp. 517-526 ◽  
Author(s):  
Euibae Lee ◽  
Sangjun Park ◽  
Yongjic Kim
Keyword(s):  
Drying Shrinkage ◽  
Dune Sand ◽  
Shrinkage Cracking

scholarly journals The Linear Hygroscopic Expansion Coefficient of Cement-Based Materials and Its Determination

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Depeng Chen ◽  
Qilin Zhu ◽  
Zhifang Zong ◽  
Tengfei Xiang ◽  
Chunlin Liu
Keyword(s):  
Finite Element ◽  
Drying Shrinkage ◽  
Simple Calculation ◽  
Thermal Shrinkage ◽  
Element Analysis ◽  
Concrete Shrinkage ◽  
Temperature Load ◽  
Cement Based Materials ◽  
The Common ◽  
Inversion Analysis

A crack caused by shrinkage could remarkably increase the permeability, heavily deteriorate the durability, and heavily deteriorate the service life of a concrete structure. However, different forms of thermal shrinkage can be predicted by directly applying a temperature load on a node. The prediction of moisture-induced stresses in cement-based materials by using the common finite element method (FEM) software is a big challenge. In this paper, we present a simple numerical calculation approach by using the proposed coefficient of hygroscopic expansion (CHE) to predict the moisture-induced deformation of concrete. The theoretical calculation formula of the linear CHE (LCHE) of cement-based material was deduced based on the Kelvin–Laplace equation and the Mackenzie equation. The hygroscopic deformation of cement mortar was investigated by inversion analysis; based on the results, the LCHE could be determined. Moreover, a case analysis of the application of LCHE to concrete is also conducted. The simulated results of concrete shrinkage were close to the experimental ones. As a whole, it is feasible to predict the drying shrinkage of concrete through simple calculation by using the proposed LCHE, which is also beneficial to the direct application of moisture loads on nodes in finite element analysis (FEA).

scholarly journals Self-consolidating mortar incorporating higher volume blended pozzolans for concrete repair

2019 ◽  
Vol 276 ◽  
pp. 01016
Author(s):  
M. Jamil ◽  
A. B. M. A. Kaish ◽  
E. I. Sahari ◽  
N. L. Fong ◽  
L. Nahar
Keyword(s):  
High Strength ◽  
Experimental Results ◽  
Cementitious Composites ◽  
Fiber Reinforced ◽  
Structural Concrete ◽  
Concrete Repair ◽  
Cement Based Materials

The challenge of repairing cracked or damaged concrete has been increasing worldwide. Several cement-based materials, such as ferrocement, fiber-reinforced cementitious mortar (FRCM), and textilereinforced mortar (TRM), have been developed and used to address the aforementioned challenge. Self-consolidating mortar is required to accelerate structural concrete repair using cementitious composites (e.g., ferrocement, FRCM, and TRM). In this study, a high-strength selfconsolidating mortar is developed using higher-volume (50% by weight of cement) blended pozzolans. Experimental results exhibit potential in terms of flowability and strength. Therefore, this type of cementitious selfconsolidating mortar can be used to expedite concrete repair or strengthening using cementitious composites.

scholarly journals Influence of Restrained Condition on Mechanical Properties, Frost Resistance, and Carbonation Resistance of Expansive Concrete

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2136
Author(s):  
Nguyen Duc Van ◽  
Emika Kuroiwa ◽  
Jihoon Kim ◽  
Hyeonggil Choi ◽  
Yukio Hama
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Frost Resistance ◽  
Total Porosity ◽  
Length Change ◽  
Ratio Test ◽  
Expansive Concrete ◽  
Restrained Condition ◽  
Carbonation Resistance ◽  
Compressive Strength Test

This paper presents the results of an experimental investigation of the effect of the restrained condition on the mechanical properties, frost resistance, and carbonation resistance of expansive concrete with different water–binder ratios. In this study, length change ratio test, expansion strain test, compressive strength test, mercury intrusion porosimetry test, underwater weighing test, freezing–thawing test, and accelerated carbonation test were performed to evaluate the mechanical properties, pore size distribution, total porosity, and durability of expansive concrete under both restrained and unrestrained conditions. The test results indicate that the length change ratio and expansion strain of the expansive concrete were controlled by the restrained condition. The compressive strength of expansive concrete was enhanced by the triaxial restraining when the amount of expansive additive was 40 kg/m3 of concrete. Two hypotheses were described to explain the change of pore structure change expansive mortar. The results also indicate that the carbonation resistance and frost resistance were improved by the uniaxial restrained condition. Furthermore, the effect of the restrained condition must be considered to evaluate not only the experimental results of the expansive concrete with a high EX replacement level but also the expansive concrete combining other cement replacement materials.

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