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 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 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.

Effect of Metakaolin on Geopolymer Industry

2019 ◽  
pp. 49-70
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Reaction Mechanisms ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
Experimental Studies ◽  
Acid Attack ◽  
Repair Materials ◽  
Hardened State

This chapter discusses the effects of metakaolin (MK) on geopolymer mortar and concrete industries. The research topics of MK-based geopolymer cover reaction mechanisms and kinetics. This chapter aims at augmenting knowledge about enhancing mechanical properties of geopolymer mortars/concrete using MK. Specifically, this chapter presents literature studies as well as current experimental studies which delineate the effect of MK on fresh and hardened-state properties of geopolymer mortars (GPMs). Properties and characteristics of metakaolin are explained followed by properties of fresh MK mortars. Properties of hardened MK concrete and durability aspects of MK mortars are explained. Applications of MK-based geopolymers and metakaolin-based geopolymers as repair materials are also included in this chapter. The results of using MK-based GPMs revealed improved workability, enhanced setting time, increased density, higher compressive strength, flexural strength, and resistance against acid attack than conventional ordinary portland cement mortar/concrete.

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.

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.

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.

The Effect of Integral Waterproof Admixture on some Mechanical Properties of Concrete, Absorption and Sulfate Attack Using Different Mix Proportions

2021 ◽  
Vol 895 ◽  
pp. 88-96
Author(s):  
Qusay A. Jabal ◽  
Mohammed Riyadh Al-Dikheeli
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Sulfate Attack ◽  
Cement Concrete ◽  
Normal Concrete

. This investigation aims to improving mechanical properties of normal concrete such as compressive strength, tensile strength, and flexural strength by using integral waterproof admixture (IWP) and also decreasing absorption of concrete, using different mix proportions of concrete, study shows a good increment of compressive strength for all mixes by using integral waterproof and also increasing the flexural and tensile strengths. The study contains also a sulfate attack study on normal mixes and integral waterproof mixes. Different percentages of IWP used in the study containing 0.0%, 1% ,1.5% and 2% for each 100 kg cement. Concrete mixes with 2% IWP admixture and 1:1:1.5 mix proportions give the highest values of compressive, tensile, and flexural strength in the study. compressive strength improved from 33.6MPa for reference 1:1:1.5 mix to 39.8 MPa by using IWP, also less absorption concrete obtained, the absorption was lowered from 3.5% to 1.7%, also deterioration in strength due to sulfate attack was small compared with reference mixes, same to other mixes 1:2:4, 1:1.5:3 that also improved by IWP admixture and lead to increasing mechanical properties and reducing absorption and sulfate attack.

Effect of high temperature on SCC containing fly ash

2021 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Mehmet Canbaz ◽  
Erman Acay
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Strength Loss ◽  
Ultrasonic Pulse Velocity ◽  
Pulse Velocity ◽  
Unit Weight ◽  
Self Compacting Concrete

The effect of high temperature on self-compacting concrete, which contains different amounts of fly ash, has been investigated. By considering the effect of concrete age and increased temperatures, the optimum fly ash-cement ratio for the optimum concrete strength is determined using experimental studies. Self-compacting concrete specimens are produced, with fly ash/cement ratios of 0%, 20% and 40%. Specimens were cured for 28, 56 and 90 days. After curing was completed, the specimens were subjected to temperatures of 20°C, 100°C, 400°C, 700°C and 900°C for three hours. After the cooling process, tests were performed to determine the unit weight, ultrasonic pulse velocity and compressive strength of the specimens. According to the experiment results, an increase in fly ash ratio causes a decrease in the compressive strength of self-compacting concrete. However, it positively contributes to self-compaction and strength loss at high temperatures. The utilization of fly ash in concrete significantly contributes to the environment and the economy. For this reason, the addition of 20% fly ash to concrete is considered to be effective.

Effect of Nano silica on strength and water absorption of cement mortar Exposed low pressure environment

2021 ◽  
Vol 06 ◽  
Author(s):  
Ai Zhang ◽  
Yong Ge
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Water Absorption ◽  
Cement Mortar ◽  
Strength Loss ◽  
Low Pressure ◽  
Low Humidity ◽  
Strength And Durability ◽  
Humidity Environment

Background: Buildings in high altitude region often face low pressure and low humidity service environment, which has a great impact on the mechanical properties and durability of cement-based materials. Objective: In this paper, the effects of nano-silica (NS) on the strength and water absorption of cement mortar exposed to the low pressure and low humidity environment were studied. Methods: Mechanical properties (compressive strength and flexural strength) and durability (water absorption) were measured. And the hydration degree of cement was tested to assist analysis. Results: The flexural strength of mortar decreased and the compressive strength increased slowly after 28 days of exposure under low pressure and low humidity environment. Especially, the introduction of 1% NS could reduce the compressive strength loss and flexural strength loss of mortar under low pressure and low humidity environment. It was also found that the water absorption of the mortar in low pressure and low humidity environment was related to the tortuous degree of the pores inside the specimen. Conclusion: The introduction of 1% NS contributed the most to the mechanical properties (compressive strength and flexural strength) and durability (water absorption) of cement mortar.

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