scholarly journals Durability Evaluation of Concrete with Multiadmixtures under Salt Freeze-Thaw Cycles Based on Surface Resistivity

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Shibin Luo ◽  
Wei Liang ◽  
Hua Wang ◽  
Wensheng Wang ◽  
Rongjun Zou
Keyword(s):  
Flexural Strength ◽  
Concrete Strength ◽  
Air Entrainment ◽  
Surface Resistivity ◽  
Mineral Admixtures ◽  
Chloride Permeability ◽  
Freeze Thaw ◽  
Air Content ◽  
Rapid Chloride Permeability ◽  
Function Relationship

According to the climatic characteristics of seasonal frozen area in northeast China, the concrete strength tests, surface resistivity, rapid chloride permeability, and freeze-thaw test under salt solution were carried out to study the influences of mineral admixtures and air content on the conventional properties and salt freeze-thaw resistance of concretes. Then, the correlation analysis of surface resistivity with strength and rapid chloride permeability were further investigated. Subsequently, the changes of cumulative mass loss and relative dynamic elastic modulus varying with salt freeze-thaw cycles were analyzed to study the influences of mineral admixtures and air content on salt freeze-thaw resistance of concrete. The test results showed that fly ash (FA) was not conducive to improve the strength and salt freeze-thaw resistance of concrete. However, blast furnace slag (BFS) and silica fume (SF) could improve the compressive and flexural strength of concrete, in which SF can improve its strength more significantly. Increasing the air content of concrete will lead to the reduction of its compressive strength, and the flexural strength first increased and then decreased. Nevertheless, the addition of air-entrainment agent (AEA) has the best effect on improving the salt freeze-thaw resistance of concrete. Moreover, surface resistivity of concrete has a good exponential function relationship with strength and a good power function relationship with rapid chloride permeability. Therefore, it is of great significance for engineering quality control and quickly and nondestructive testing.

Mechanical Characteristics of Concrete Exposed to External Flexural Load, De-Icing Salt and Freeze-Thaw Cycles

2011 ◽  
Vol 250-253 ◽  
pp. 33-39
Author(s):  
Xiao Lu Yuan ◽  
Bei Xing Li ◽  
Shang Chuan Zhao ◽  
Shi Hua Zhou
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Ordinary Portland Cement ◽  
Mechanical Characteristics ◽  
Concrete Strength ◽  
Mineral Admixtures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Freeze Thaw

This paper investigates mechanical characteristics of concrete exposed to external flexural load, de-icing salt and freeze-thaw cycles. Concrete specimens made with ordinary Portland cement or ordinary Portland cement incorporating fly ash with the replacement of 10% or 20%, or 0.7/10000 air-entraining agent and 20% fly ash, or ground blast furnace slag with the replacement of 15% or 30%, were made and exposed to flexural load, freeze-thaw and de-icing salt environment. Mechanical properties of concrete including compressive strength and flexural strength were measured. Phase composition of samples was determined by means of x-ray diffraction (XRD). Results indicate that increasing flexural stress ratios reduced compressive strength and flexural strength of concrete, and presented higher improvement of mineral admixtures in concrete strength. Incorporation of mineral admixtures and air-entraining agent decreased the loss of concrete strength. X-ray diffraction analysis showed the presence of abundant calcium chloroaluminate and ettringite in paste samples.

Investigation of Critical Quality Assurance Parameter Variations for Concrete

1997 ◽  
Vol 1575 (1) ◽  
pp. 92-101
Author(s):  
Richard K. Smutzer ◽  
Sedat Gulen ◽  
Youlanda K. Belew ◽  
Virgil L. Anderson
Keyword(s):  
High Pressure ◽  
Quality Assurance ◽  
Flexural Strength ◽  
Concrete Strength ◽  
Pulse Velocity ◽  
Hardened Concrete ◽  
Army Corps ◽  
Split Tensile Strength ◽  
Air Content ◽  
Concrete Mix

The Indiana Department of Transportation is involved in preparing statistically sound specifications for strong and durable concrete used in quality assurance programs. Previous laboratory studies relating concrete strength to air content and concrete mix designs dealt with variation in compressive strength. This study searched for a statistically sound relationship between air content, concrete mix designs, and flexural strength. This study also developed a high-pressure method of hardened concrete air content determination. Sixty-four independent batches (combinations) of concrete were produced, each batch was subjected to a total of 24 tests—4 plastic and 20 hardened. The design factors were aggregate type and gradation, plastic air content, cement, and pozzolanic content and testing operator. After plastic testing, three flexural strength beams were cast from each batch of concrete. The experimental design response variables consisted of flexural, compressive, and split tensile strength along with pulse velocity. Analysis of variances, indicated that the optimum flexural strength could be obtained using as-received stone course aggregate and an air content of between 6 percent and 7.9 percent, with no fly ash. A high-pressure air meter, similar to the meter developed by the Army Corps of Engineers, was used. A strong statistical correlation of determination, r2 = 0.94, was obtained between plastic and the hardened concrete air content using this meter.

scholarly journals Investigation on Durability Behaviour and Optimization of Concrete with Triple-Admixtures Subjected to Freeze-Thaw Cycles in Salt Solution

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xuejiao Li ◽  
Wensheng Wang ◽  
Zhiqing Zhu ◽  
Kunkun Zheng
Keyword(s):  
Salt Solution ◽  
Coupling Effect ◽  
Orthogonal Experiment ◽  
Cold Climate ◽  
Working Environment ◽  
Mineral Admixtures ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Freeze Thaw ◽  
Air Entrained Concrete

In the seasonal frozen area of northeast China, cement concrete is usually in a working environment of cold climate and chlorine erosion coupling effect. In general, with a reasonable addition of air entraining agent (AEA) and multimineral admixtures such as fly ash, blast furnace slag, and silica fume, the durability of cement concrete under the effects of freeze-thaw and salt solution can be significantly improved in cold regions. However, due to several more compositions of cement concrete with multiple mineral admixtures, it would take excessive trial mixtures to select the desired mixture proportion based on the conventional method. This means a great deal of costs of raw materials and laboratory experimental time. In this paper, the experimental scheme of mixture proportion for air-entrained concrete with multimineral admixtures was designed based on the orthogonal experiment design method. Based on the compressive strength, rapid chloride permeability, and weight loss and relative dynamic elastic modulus after salt freeze-thaw cycles, the influence of different mineral admixtures and their dosages on the durability of concrete subjected to freeze-thaw in salt solution was analyzed. After that, based on genetic algorithm, an optimization of mixture proportion was proposed, which only requires less trial mixes and accessible optimization process. The test results indicated the superiority of air-entrained concrete with multimineral admixtures when serving in salt freeze-thaw environment. Eventually, it was also verified that the optimized concrete in this paper could achieve pleasurable durability performances under salt freeze-thaw cycles.

Surface Resistivity Measurements Evaluated as Alternative to Rapid Chloride Permeability Test for Quality Assurance and Acceptance

2012 ◽  
Vol 2290 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Tyson D. Rupnow ◽  
Patrick J. Icenogle
Keyword(s):  
Cost Benefit ◽  
Cementitious Materials ◽  
Surface Resistivity ◽  
Test Results ◽  
Permeability Test ◽  
Chloride Permeability ◽  
Resistivity Measurements ◽  
Wide Range ◽  
Rapid Chloride Permeability ◽  
Resistivity Meter

ASTM C1202 tests were conducted at various ages with the corresponding surface resistivity test, and the results were compared. Samples tested included field- and laboratory-prepared samples. The laboratory test matrix tested several mixtures common to Louisiana at a wide range of ratios of water to cementitious materials (w/cm) to evaluate the range of the surface resistivity meter. The surface resistivity measurements correlated well with rapid chloride permeability measurements across a wide range of permeability values and sample testing ages. Suitable correlations were found between both the 14-day and the 28-day surface resistivity values and the 56-day rapid chloride permeability values. The variability of the surface resistivity test results is usually less than the variability of the rapid chloride permeability test results. The surface resistivity meter was also able to identify great differences in w/cm ratios for the same mixtures. The surface resistivity meter was determined to be user friendly. The preliminary cost–benefit analysis showed that implementation of the device would save the department about $101,000 in personnel costs in the first year. It is estimated that contractors would save about $1.5 million in quality control costs. The cost–benefit ratio for this project is estimated to be about 15. A Louisiana Department of Transportation and Development test requirements procedure, TR 233, has been developed and implementation of the surface resistivity device has begun.

Properties of Polyacrylic Ester Latex Modified Cement Mortar

2013 ◽  
Vol 687 ◽  
pp. 166-174 ◽  
Author(s):  
Zhen Ping Sun ◽  
Dan Mei Ye ◽  
Le Feng Fu ◽  
Bo Cun Zheng ◽  
Zhong Jun Feng ◽  
...  
Keyword(s):  
Adverse Effect ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Cement Mortar ◽  
Air Entrainment ◽  
Hydration Process ◽  
Air Content ◽  
Retarding Effect ◽  
Polyacrylic Ester

The water reducing performance, retarding effect, air entrainment, flexural and compressive strength of polyacrylic ester (PAE) latex modified cement mortar were investigated with fixed flow values. The research shows that PAE latex has water-reducing performance. The amount of water used in modified cement mortar decreases with increasing dosage of PAE latex. Because of the retarding effect, PAE latex delays the hydration process of cement. PAE latex has a strong effect of air entraining, and the air content of fresh mortar can be controlled by suitable dosage of defoamer. With the same air content of fresh mortar, PAE latex can obviously improve the flexural strength of cement mortar, and has no adverse effect on its compressive strength.

The Effect of HRWR and AEA on the Air System of Vibrated Concrete

2015 ◽  
Author(s):  
Ahmad Ghadban ◽  
Mohammed Albahttiti ◽  
Kyle Riding ◽  
David Lange
Keyword(s):  
Rheological Properties ◽  
Precast Concrete ◽  
Air Entrainment ◽  
System Stability ◽  
Unit Weight ◽  
Time Duration ◽  
Freeze Thaw ◽  
Air Content ◽  
Air System ◽  
The Stability

Air entrainment in concrete railroad ties is typically included to prevent freeze-thaw damage. Uniformly-distributed microscopic air voids in concrete ties helps to resist against freeze-thaw. The air entrainment system stability with time after mixing is dependent on a number of factors which include chemical, environmental, and construction related parameters. These resulting differences in the air void system can in turn lead to different performances of concrete under freeze-thaw loading. Vibration is mainly used to consolidate concrete but can also alter the air structure of concrete. This study investigates the effect of different chemical admixtures and rheological properties on the stability of the air system inside vibrated concrete. Form vibration of 75 Hz frequency and 3 g or 10 g peak acceleration was applied to the tested concrete after the lapse of several time durations. This was done to investigate the stability of the air system of concrete as time passes on under different vibration conditions. The testing included slump, unit weight, temperature, rheology and fresh air content before vibration and after vibration for each elapsed time duration. Fresh air content tests showed that the air loss increases linearly with time for almost all mixtures. Concrete rheological properties immediately after mixing were not a good indicator of the concrete air system stability after delayed placement. Tall oil based air entraining agents (AEA) was found to produce slightly lower air instability; however, the differences between AEA were small. The results showed that for precast concrete railroad ties, any instability with time of entrained air should not be a significant problem for precast concrete railroad tie plants if the concrete is placed and consolidated within 30 minutes from mixing at room temperatures.

scholarly journals Impact of Air Entrainment on the Microstructure and Mechanical Performance of High Performance Mortar

2014 ◽  
Vol 629-630 ◽  
pp. 358-365
Author(s):  
Jeroen Dils ◽  
Veerle Boel ◽  
Geert de Schutter
Keyword(s):  
Pore Structure ◽  
High Performance ◽  
Mercury Intrusion Porosimetry ◽  
Mechanical Performance ◽  
Air Entrainment ◽  
Air Bubbles ◽  
Mercury Intrusion ◽  
Freeze Thaw ◽  
Air Content ◽  
Air Entraining Agents

High performance self-compacting mortar has the ability to push out air bubbles under its own weight. Consequently, the resistance against freeze-thaw cycles with or without deicing salts can decrease due to the total air content reduction. In order to assure the necessary expansion zones1,2 air entraining agents (AEA) are commonly used to increase the amount of stable air bubbles. Depending on the mixture, the workability and rheology decrease or increase by the entrained air bubbles3. This will depend on the ratio between the surface tension and the shear stress applied during the test. If the latter can overcome the first, the bubbles will deform and increase the fluidity of the mixture. Besides the influence on the durability and the fresh concrete, air entraining agents also alter the pore structure and the mechanical performance of the mortar. The effect of AEA on these properties is the subject of this paper. The pore structure is examined on two different levels. On the one hand, mercury intrusion porosimetry is used to investigate the capillary porosity, ranging from 10 nm to 10 μm. On the other hand air void analysis and fluorescence microscopy is performed to evaluate the larger air bubbles ranging from 0.1 mm to 1 mm4. Both techniques showed an overlap in their measuring range. Consequently it was possible to compare the techniques critically. Similar as in literature, mercury intrusion porosimetry underestimates the amount of larger air bubbles in mortar, due to its measuring principle5. Furthermore, the bubbles with a diameter of 80 μm increase significantly by the addition of AEA. This confirms the average air bubble size often used in literature to explain the influence of AEA on the workability and rheology3. The influence of air entraining agent on the mechanical performance was tested by the compressive and bending tensile strength. In conclusion, a good balance is necessary between the air content necessary for a proper freeze-thaw resistance without changing the mechanical performance drastically.

The Time-Dependence of Chloride Penetration Resistance of Concrete by the Rapid Chloride Permeability Test

2013 ◽  
Vol 357-360 ◽  
pp. 651-654 ◽  
Author(s):  
Yan Jun Hu ◽  
Yan Liang Du
Keyword(s):  
Penetration Resistance ◽  
Chloride Penetration ◽  
Mineral Admixtures ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Curing Time ◽  
Permeability Test ◽  
Chloride Permeability ◽  
Chloride Penetration Resistance ◽  
Rapid Chloride Permeability

In this paper, the Rapid Chloride Permeability Test (RCPT)-ASTM C1202-91 and Conductance test were employed to measure the effect of curing time on the chloride penetration resistance of concrete. The results indicate that the concrete specimens with longer curing time have higher chloride penetration resistance no matter the concrete with or without mineral admixtures, the concrete conductance has the similar variation trend and similar mathematical descriptions as the chloride diffusion coefficient D with the passage of curing time, and it is a very useful method to measure concrete conductance to estimate the chloride permeability variation at different curing or exposure time.

Effect of ground granulated blast funrnace slag and fly ash on strength, permeability, and under-water abrasion of fine-grained concrete

2020 ◽  
Vol 71 (7) ◽  
pp. 775-788
Author(s):  
Quyet Truong Van ◽  
Sang Nguyen Thanh
Keyword(s):  
Fly Ash ◽  
Concrete Strength ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chloride Permeability ◽  
Cement Replacement ◽  
Fine Grained ◽  
Granulated Blast Furnace Slag ◽  
Compressive Strength Test ◽  
Economic Ground

The utilisation of supplementary cementitious materials (SCMs) is widespread in the concrete industry because of the performance benefits and economic. Ground granulated blast furnace slag (GGBFS) and fly ash (FA) have been used as the SCMs in concrete for reducing the weight of cement and improving durability properties. In this study, GGBFS at different cement replacement ratios of 0%, 20%, 40% and 60% by weight were used in fine-grained concrete. The ternary binders containing GGBFS and FA at cement replacement ratio of 60% by weight have also evaluated. Flexural and compressive strength test, rapid chloride permeability test and under-water abrasion test were performed. Experimental results show that the increase in concrete strength with GGBFS contents from 20% to 40% but at a higher period of maturity (56 days and more). The chloride permeability the under-water abrasion reduced with the increasing cement replacement by GGBFS or a combination of GGBFS and FA

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