scholarly journals Damage Evolution of Concrete Exposed to Sulfate Attack Under Drying-Wetting Cycles

2014 ◽  
Vol 8 (1) ◽  
pp. 444-449
Author(s):  
Lei Jiang ◽  
Ditao Niu
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Layer Thickness ◽  
Damage Evolution ◽  
Sulfate Solution ◽  
Strength Loss ◽  
Damage Mechanism ◽  
Sulfate Attack ◽  
Corrosion Products ◽  
Damage Layer

The damage evolution of concrete subjected to drying-wetting cycles in different concentration of sodium sulfate solution was investigated based on micro and macro-observations. Through the experiment, weight loss, compressive strength loss and the damage layer thickness of concrete were measured after different drying-wetting cycles. The mechanical properties degradation in the damage layer of concrete was also analyzed. Furthermore, the scanning electron microscopy and X-ray diffraction were used to investigate the corrosion products of concrete, and the damage mechanism was also investigated by the modern microanalysis techniques. The test results show that the deterioration degree of physical properties of concrete specimens increases with increasing concentration. Weight loss of specimens caused by sulfate attack is not obvious compared with the other evaluation index. When the damage layer thickness of concrete is thicker as well as the ultrasonic speed is lower, indicating that the deterioration degree of concrete increases, and the compressive strength loss in damage layer is serious. It was also found that the compressive loss of concrete is correspond with the observations for the damage layer thickness. Additionally, the main corrosion products of concrete in sulfate solutions subjected to drying-wetting cycles were confirmed to be ettringite and gypsum, and the quantity of corrosion products formed is proportional to the concentration of the solution.

scholarly journals The Effect of Sulfate Attack on Physical Properties of Concrete

2021 ◽  
Vol 10 (2) ◽  
pp. 21-27
Author(s):  
Pooja Kanaujia ◽  
◽  
Rajiv Banerjee ◽  
Syed Mohammad Ashraf Husain ◽  
Sabih Ahmed ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Experimental Studies ◽  
Sulfate Solution ◽  
Strength Loss ◽  
Sulfate Attack ◽  
Mold Growth ◽  
Concrete Blocks ◽  
Weight Analysis ◽  
Density Analysis

The effects of different concentrations of sulfate for erosion age on compressive strength, flexural strength, weight analysis, density loss and visual appearances for concrete specimens of different grades were investigated. Experimental studies were carried out on different grades of concrete (M-25, M-30 and M-35). Concrete specimens were immersed in different concentration of sulfate solution i.e. 4.0pH, 5.0pH and 6.0pH. Reduction in compressive strength loss was noticed when the grade of concrete is increased from M-25 to M35. The results of weight analysis and density analysis also confirm the compressive strength loss and flexural strength. Discoloration of concrete was noticed on the concrete blocks when left immersed in sulfate solution at 4.0pH, 5.0pH and 6.0pH for 75days and 90days. It appeared like flakes of concrete and resembled like mold growth.

scholarly journals Experimental Study on Mechanical Properties of High-Ductility Concrete against Combined Sulfate Attack and Dry–Wet Cycles

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4035
Author(s):  
Lingling Li ◽  
Junping Shi ◽  
Jialiang Kou
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Loss Rate ◽  
Rapid Development ◽  
Engineering Application ◽  
Sulfate Solution ◽  
Strength Loss ◽  
Sulfate Attack ◽  
High Ductility ◽  
Chemical Attack

Concrete will deteriorate and damage under sulfate attack. In order to study the degradation characteristics of HDC under sulfate attack, the mechanical properties of high-ductility concrete (HDC) were investigated using the uniaxial compressive strength test of HDC specimens soaked in different concentrations of sulfate solution and subjected to different times of dry–wet cycles. The variations in the compressive strength, loss rate of compressive strength, and the max compressive strength under the action of sulfate attack and dry–wet cycles were analyzed. The analytical expressions of damage variables were given. SEM was used to observe the microstructure of the sample, and the microdamage mechanism of the HDC was explored. The deterioration of the HDC was found to be the result of the combined action of sulfate attack and dry–wet cycles and was caused by physical attack and chemical attack. PVA prevented the rapid development of deterioration. On the basis of the change of compressive strength, the damage variable was established to quantitatively describe the degree of damage to HDC. The experimental results showed that with the increase in the number of dry–wet cycles, the compressive strength of HDC generally increased first and then decreased. As the concentration of the sulfate solution increased, the loss rate of the compressive strength of HDC generally increased and the max compressive strength gradually decreased. With the increase in the number of dry–wet cycles, HDC first showed self-compacting characteristics and then gradually became destroyed. Compared with ordinary concrete (OC), HDC is superior to OC in sulfate resistance and dry–wet cycles. This study provided a test basis for the engineering application of HDC in sulfate attack and dry–wet cycles environment.

scholarly journals Deterioration and Microstructural Evolution of the Fly Ash Geopolymer Concrete against MgSO4Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Long ◽  
Qingyuan Wang ◽  
Zhongwei Guan ◽  
Yu Chen ◽  
Xiaoshuang Shi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Magnesium Sulfate ◽  
Strength Loss ◽  
Sulfate Attack ◽  
Aluminum Silicate ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Sodium Aluminum Silicate ◽  
Magnesium Aluminum Silicate

Fly ash geopolymer concrete (FAGC) and ordinary Portland cement concrete (OPCC) specimens were immersed in 5% MgSO4solution undergoing 32 wetting-drying and heating-cooling cycles. Their compressive behavior was investigated after every 8 cycles. Several microstructure analysis techniques were applied on the samples to identify the materials formed due to magnesium sulfate attack, including XRD, FTIR, SEM, and EDS. Experimental results elucidated that the compressive strength loss ratio in the heating group of FAGC was 12.7%, while that of OPCC was 17.8%, which means that FAGC had better magnesium sulfate resistance than OPCC. The compressive strength loss of OPCC was due to the formation of gypsum under the magnesium sulfate attack exposed to wetting-drying and heating-cooling cycles. The deterioration mechanisms of FAGC against MgSO4solution were discovered to be that sodium aluminum silicate hydrate (N-A-S-H) gels reacted with MgSO4, leading to the creation of low strength magnesium aluminum silicate hydrate (M-A-S-H) gels.

Durability of Sugar Cane Bagasse Ash (SCBA) Concrete towards Chloride Ion Penetration

2014 ◽  
Vol 567 ◽  
pp. 369-374 ◽  
Author(s):  
Nasir Shafiq ◽  
Asma Abd Elhsameed ◽  
Muhd Fadhil Nuruddin
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Penetration Depth ◽  
Sugar Cane ◽  
Fine Particles ◽  
Strength Loss ◽  
Sugar Cane Bagasse ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Sugar Cane Bagasse Ash

In this study, the effect of sugar cane bagasse ash (SCBA) on chloride penetration resistance of concrete was investigated. 100-mm side cubes were cast and cured in water for 28 days followed by six months curing in 4% NaCl solution. The resistance to chloride penetration was assessed by measuring the chloride penetration depth, weight loss, compressive strength loss and bond strength loss. Chloride penetration depth was measured using AgNO3–based method. It was obtained that inclusion of SCBA in concrete significantly reduced the chloride penetration depth, weight loss, compressive strength loss and bond loss that was attributed to the fine particles of SCBA that filled up the pores and prevented the chloride ingress in the concrete.

scholarly journals Feasibility study of compost as a partial substitute for fine aggregate in concrete

2021 ◽  
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Fine Particles ◽  
Strength Loss ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Control Specimen ◽  
Sem Image ◽  
Significant Difference

Abstract In this study, vermicompost is replaced for fine aggregate in geopolymer concrete (GPC). Initially mix design is made for GPC and mix proportion is proposed. The vermicompost is replaced at 5%, 10%, 15% and 20% with M sand in GPC. Result indicates the 5% replacement with vermicompost based geopolymer concrete (GPVC) has the compressive strength of 32 N mm−2 (M30 grade) whereas the compressive strength of control specimen made with GPC is 37 N mm−2. Other replacement shows 21 N mm−2, 14 N mm−2 and 11 N mm−2 respectively. The 5% replaced concrete cubes and control specimen are tested at an elevated temperature of 200°C, 400°C, 600°C and 800°C and compared with the control specimen. There is no significant difference observed in weight lost at control (GPC) and GPVC specimen. An elevated temperature, the weight loss is almost 4% at 200°C because of expulsion of water from the concrete. Afterwards only 2% weight loss is observed in remaining elevated temperature. The compressive strength loss is observed at an elevated temperature in GPC and GPVC specimen because of thermal incompatibility between aggregate and the binder. EDX results show M sand and compost contains Si, Al, C, Fe, Ca, Mg, Na and K and it is similar in the elemental composition and SEM image confirms vermicompost contains fine particles.

Application of Nano Silica in Concrete for Enhanced Resistance against Sulfate Attack

2013 ◽  
Vol 829 ◽  
pp. 874-878 ◽  
Author(s):  
Amir Mahdi Moslemi ◽  
Arash Khosravi ◽  
Mohsen Izadinia ◽  
Mohaddeseh Heydari
Keyword(s):  
Compressive Strength ◽  
Concrete Structure ◽  
Concrete Specimen ◽  
Sulfate Solution ◽  
Critical Issue ◽  
Sulfate Attack ◽  
Pozzolanic Material ◽  
Enhanced Resistance ◽  
Morphology Characteristics ◽  
Durability Of Concrete

Durability of concrete structure is a critical issue especially in severe environment when the concrete structure is exposed to sulfate attack, such as shorelines. nanoSilica is high pozzolanic material which is used recently in concrete to improve its mechanical properties. However, the durability of concrete against sulfate attack containing nanoSilica (NS) has not been investigated completely. In this study, the effects of NS has been studied on compressive strength, sulfate attack and morphology characteristics. The results show that increasing of compressive strength in specimens with NS is significant in early ages. Resistance of concrete specimen against sulfate attack was measured in 5% sodium sulfate solution for expansion of prime specimens. After a period of 180 days the samples containing zero, 2, 4, 6 and 8% NS lost 3.51%, 2.4%, 2.23%, 1.13% and 1% of their weights compared to the initial weights, respectively. The results indicate that the concrete samples containing 8% NS show best performance in terms of resistance against sulfate attack.

Study on Fire Resistance of Cement

2013 ◽  
Vol 320 ◽  
pp. 308-313
Author(s):  
Lian Wei Shan ◽  
Jun Li Zhang ◽  
Wei Li ◽  
Zhao Jing Liu ◽  
Ze Wu ◽  
...  
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Chemical Composition ◽  
Theoretical Analysis ◽  
Internal Structure ◽  
Fire Resistance ◽  
Room Temperature ◽  
Strength Loss ◽  
Hydration Products

This work aims to study the effect of sintering temperatures on the compressive strength and weight of net cement. The compressive strength and quality variety of cement which undergo different sintering temperatures (400°C, 600°C, 800°C, 900°C) and sintered at different times (1h, 2h) are studied through experiments and theoretical analysis. By using XRD explore the inner of sample chemical composition and further obtain the mechanism about sample of weight loss and strength loss. The main internal components of cement are Ca (OH)2, C-S-H, Ca2SiO3 and CaCO3 at room temperature. When the temperature was up to 400°C, The internal structure of cement started to be destroyed due to its hydration products C-S-H, Ca (OH)2 and CaCO3 began to decompose slowly. Keywords: Cement, Fire resistance, Compressive strength

Application of Non-Destructive Technology in Evaluating Concrete to Sulfate Attack

2010 ◽  
Vol 168-170 ◽  
pp. 2565-2570 ◽  
Author(s):  
Xu Guang Tang ◽  
You Jun Xie ◽  
Guang Cheng Long
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Chemical Erosion ◽  
Dynamic Modulus Of Elasticity ◽  
Non Destructive

The deterioration on sulfate attack was investigated both in physical crystallization and the chemical erosion. Specimens that suffered long-term immersion and dry-wet cycles in saturated sodium sulfate solution are compared to trace the physical attack. And the chemical erosion was conducted by comparing specimens which have been suffered long-term immersion in saturated sodium sulfate solution and saturated limestone solution. In the investigation, the non-destructive detecting indexes, such as the ultrasonic velocity, and the dynamic modulus of elasticity were measured. The permeability, the porosity and mechanical strength at 28-day age were measured. The flexural/compressive strength was measured after 90 wet-dry cycles. And then all the specimens were cut into cubes to take the measure of compressive strength. Based on the experiments, feasibility of various parameters, such permeability, relative dynamic modulus of elasticity, ultrasonic velocity and relative flexural/compressive strength, were investigated to evaluate the concrete deterioration. The results indicate that there is a close relationship between the deterioration by sulfate attack and concrete permeability, so the reduction of permeability is effective in promoting the resistance. The index of the resistance expressed by the dynamic modulus of elasticity ratio is comparable to that expressed by the relative flexural strength. A novel method was suggested in evaluating concrete by sulfate attack, namely, combined with some mechanical tests, the parameter of relative dynamic modulus of elasticity can be used to evaluate the deterioration; the permeability denoted as the amount of transporting charges within 6 hours can be used to evaluate the properties to sulfate attack.

Behaviors of Long-Term Exposure Concrete to Sulfate Solution

2011 ◽  
Vol 368-373 ◽  
pp. 790-794
Author(s):  
Shun Bo Zhao ◽  
Thomas C.K. Molyneaux ◽  
David W. Law ◽  
Yong Li ◽  
Li Yun Pan
Keyword(s):  
Compressive Strength ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sulfate Ions ◽  
Sulfate Solutions ◽  
Collaborative Studies ◽  
Diffusion Depth ◽  
One Year ◽  
The Uk

As a part of the collaborative studies between China, Australia and the UK, examing sulfate attack on concrete, this paper reports the experimental results obtained from the Chinese laboratory. Specimens were immersed in sodium and magnesium sulfate solutions with concentrations of 500mg/L, 5000mg/L and 50000mg/L. Investigations were conducted over approximately a one year period. Susceptibility to sulfate attack was assessed in terms of changes in the mass and length of specimens, the compressive strength of the concrete, as well as the diffusion depth of sulfate-ions into the concrete at fixed intervals. Several differences were observed between these results and those reported in studies from the UK laboratory.

scholarly journals Mechanical Properties and Damage Evolution of Concrete Materials Considering Sulfate Attack

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2343
Author(s):  
Qianyun Wu ◽  
Qinyong Ma ◽  
Xianwen Huang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Damage Evolution ◽  
Resistance Coefficient ◽  
Sulfate Attack ◽  
Micro Structure ◽  
Micro Cracks ◽  
Concrete Damage ◽  
Concrete Materials

In order to study the durability of concrete materials subjected to sulfate attack, in a sulfate attack environment, a series of concrete tests considering different fly ash contents and erosion times were conducted. The mechanical properties and the micro-structure of concrete under sulfate attack were studied based on the following: uniaxial compressive strength test, split tensile test, ultrasonic impulse method, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties were compressive strength, splitting tensile strength, and relative dynamic elastic modulus, respectively. Additionally, according to the damage mechanical theory, experimental results and micro-structure analysis, the damage evolution process of concrete under a sulfate attack environment were studied in detail. Finally, according to the sulfate attack time and fly ash content, a damage model of the sulfate attack of the binary surface was established. The specific results are as follows: under the action of sulfate attack, the change law of the rate of mass change, relative dynamic modulus of elasticity, corrosion resistance coefficient of compressive strength, and the corrosion resistance coefficient of the splitting tensile strength of concrete all increase first and then decrease. Under the same erosion time, concrete mixed with 10% fly ash content has the best sulfate resistance. Through data regression, the damage evolution equation of the sulfate attack was developed and there is an exponential function relationship among the different damage variables. The binary curved surface regression effect of the concrete damage and the erosion time and the amount of fly ash is significant, which can predict deterioration of concrete damage under sulfate attack. During the erosion time, the combined expansion of ettringite and gypsum caused micro cracks. With an increase of corrosion time, micro cracks developed and their numbers increased.

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