Resistance of Concrete to Na2SO4 Freeze-Thaw Cycles and Failure Mechanism Analysis

2016 ◽  
Vol 711 ◽  
pp. 335-342 ◽  
Author(s):  
Guo Li ◽  
Jian Min Du ◽  
Xiao Suo Wu ◽  
Kun Yang
Keyword(s):  
Tap Water ◽  
Mechanism Analysis ◽  
X Ray Diffraction ◽  
Freeze Thaw ◽  
Ettringite Formation ◽  
Mass Losses ◽  
Thaw Cycle ◽  
Concrete Failure ◽  
Gypsum Formation ◽  
Freeze Thaw Cycle

Rapid freeze–thaw cycle experiments were carried out on concrete specimens with 0.4, 0.5, and 0.6 water–cement (w/c) ratio in 0% (tap water), 1%, and 5% Na2SO4 solutions, respectively, to study the performance of ordinary concrete resistance to sulfate freeze–thaw cycle. The specimens underwent visual inspection, and mass losses and relative dynamic elastic modulus (RDEM) were measured regularly. Scanning electron microscope observation and X-ray diffraction analysis were conducted on partial specimens after the freeze–thaw cycle experiment. Research results show that due to the coupling effects of freeze–thaw cycle and sulfate corrosion, freeze–thaw cycles of concrete in Na2SO4 solution caused more damages than in tap water. Higher Na2SO4 concentration produced severe damages. Concrete with different w/c ratios exhibit different sulfate freeze–thaw cycle resistances, and concrete with lower w/c ratio usually produces stronger resistance. RDEM loss is considered the control index to determine concrete failure. The corrosion products in Na2SO4 solution freeze–thaw cycle are mainly ettringite and gypsum. With the increase in Na2SO4 concentration, ettringite formation gradually decreases and gypsum formation gradually increases.

A Preliminary Research on Alkali-Activated Slag Concrete as Tunnel Lining in Severe Frigid Regions

2013 ◽  
Vol 668 ◽  
pp. 65-69 ◽  
Author(s):  
Heng Shu
Keyword(s):  
Frost Damage ◽  
Sem Analysis ◽  
Tunnel Lining ◽  
X Ray Diffraction ◽  
Alkali Activated Slag ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Activated Slag ◽  
Alkali Activated

The main structure materials of tunnel lining are concrete and steel, and the concrete frost damage is a typical degradation phenomenon of the tunnel linings in cold regions. Alkali-activated slag concrete (ASC) has a better freeze-thaw resistance, which can be used for tunnel lining in severe frigid regions. Freeze-thaw resistance, performance mechanism of ASC and microstructure were investigated by freeze-thaw cycle, X-ray diffraction (XRD) and Scanning electron microscope (SEM) analysis. The experimental results show that, ASC has excellent freeze-thaw resistance, and hydration products of ASC are mostly C-S-H, alkaline aluminosilicate. ASC has a good compact degree and uniformity of structure, and its high compressive strength also makes high freeze-thaw resistance. ASC may be selected as tunnel lining production materials in severe frigid regions because of the less reduction in the dynamic elastic modulus and mass loss of concrete.

Experiment Study on the Effect of GGBFS on Frost Resistance of Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 207-212 ◽  
Author(s):  
Shi Yi Zhang ◽  
Ying Fang Fan ◽  
Qi Wang
Keyword(s):  
Electron Microscopy ◽  
High Performance ◽  
Plain Concrete ◽  
Industrial Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Scanning Electron

High volume utilization of industrial wastes and by products is the solution for high disposal coast. The anti-frost of high performance concrete is a key factor for safe utilization of concrete structure containing industrial wastes under severe environment. In this paper, to understand the property on anti-frost of high performance containing ground granulated blast furnace slag (GGBFS) under cold marine environment. Some comparison studies were conducted on plain concrete by rapid freeze-thaw cycle test. During the rapid freeze-thaw cycle test, the mass loss and relative elastic modulus were measured regularly at the prescribed conditioning ages. The development of microstructure in concrete was analyzed through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The rapid freeze-thaw cycle test results show that the plain concrete was destroyed severely at 150 freeze-thaw cycles. After 225 freeze-thaw cycles, the mass loss and the relative dynamic modulus of elasticity of GGBFS concrete decrease 1.3% and 26.11%, respectively, that indicates that GGBFS significantly improve the anti-frost performance of concrete; The addition of GGBFS can accelerate the cement hydration reaction, promote more Ca (OH)2 crystals shift to C-S-H gel and help to increase the density of the micro-structure of concrete, which can prevent the formation of micro-cracks and suppress the propagation of cracks and thus effectively improve the durability of concrete. KEY WORDS: GGBFS; freeze-thaw durability; microstructure; scanning electron microscopy; X-ray diffraction.

scholarly journals Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Longxiao Chen ◽  
Kesheng Li ◽  
Guilei Song ◽  
Deng Zhang ◽  
Chuanxiao Liu
Keyword(s):  
Mechanical Properties ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Physical And Mechanical Properties ◽  
Freeze Thaw ◽  
Damage Characteristics ◽  
Large Pore ◽  
Natural Rock ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

Non-linear creep damage model of sandstone under freeze-thaw cycle

2021 ◽  
Vol 28 (3) ◽  
pp. 954-967
Author(s):  
Jie-lin Li ◽  
Long-yin Zhu ◽  
Ke-ping Zhou ◽  
Hui Chen ◽  
Le Gao ◽  
...  
Keyword(s):  
Damage Model ◽  
Creep Damage ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Linear Creep ◽  
Non Linear ◽  
Freeze Thaw Cycle ◽  
Creep Damage Model

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

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.

Protection of osteoblastic cells from freeze/thaw cycle-induced oxidative stress by green tea polyphenol

2005 ◽  
Vol 27 (9) ◽  
pp. 655-660 ◽  
Author(s):  
Dong-Wook Han ◽  
Hak Hee Kim ◽  
Mi Hee Lee ◽  
Hyun Sook Baek ◽  
Kwon-Yong Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Green Tea ◽  
Osteoblastic Cells ◽  
Tea Polyphenol ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Green Tea Polyphenol ◽  
Freeze Thaw Cycle
Sign in / Sign up

Export Citation Format

Share Document