The effect of foam fractionated lignosulphonates on air entrainment in concrete

1982 ◽  
Vol 9 (2) ◽  
pp. 170-175
Author(s):  
K. F. Keirstead ◽  
D. DeKee ◽  
D. W. Kirk ◽  
S. U. Pillai
Keyword(s):  
Surface Tension ◽  
Air Entrainment ◽  
Hardened Concrete ◽  
Air Voids ◽  
Air Content ◽  
Low Concentrations ◽  
Tension Properties ◽  
Air Entraining Agents ◽  
Air Void ◽  
Mixing Water

One of the properties of air-entraining admixtures that may influence their efficiency is their surface tension when combined with mixing water. Lignosol SF is a standard air-entraining agent. With the objective of identifying a product with improved qualities, Lignosol SF was fractionated and two of its fractions, respectively with low (foamate) and high (retentate) surface tension properties were investigated as potential air-entraining agents. Measurements were made both of air content in wet concrete mix and of the air-void characteristics of the hardened concrete.The results showed that at low concentrations and water:cement ratios the performance of all the three products above are similar. However, the foamate fraction becomes more effective in entraining air with increases in concentration and water:cement ratio. Further, this foamate resulted in the hardened concrete having bubbles with a smaller mean diameter than those in the retentate. The spacing factors for both these products were within recommended limits. Keywords: admixtures; air-entrainment; air-voids; concrete; freeze-thaw resistance; Lignosol; spacing factor.

Influence of Air Content and Vibration Time on Frost Resistance of Air Entrained Concrete

2013 ◽  
Vol 857 ◽  
pp. 110-115 ◽  
Author(s):  
Xiu Hua Zheng ◽  
Yong Ge ◽  
Jie Yuan
Keyword(s):  
Frost Resistance ◽  
Hardened Concrete ◽  
Air Voids ◽  
Air Content ◽  
High Durability ◽  
Void Structure ◽  
Vibration Time ◽  
Air Void ◽  
Air Void Structure ◽  
Air Entrained Concrete

Air-entraining agent turely is one of the necessary compositions of the high durability concrete. The influence of air content and vibration time on the frost resistance of concrete was researched, and air void characteristics of hardened concrete was analysed. The results showed that the air contents could reduce the compressive strengthof hardened concrete excessively, but it made the spacing factor reduce obviously and significantly improve the frost resistance of concrete.The air voids with different structure in concrete were realized by vibration time. It was found that the air void structure and the frost resistance properties were influenced by the vibration time largely. The optimized vibration time is 30s, the appropriate vibration time is 20s~30s, no more than 35s.

scholarly journals The Relationship between the Air Content in the Mortar and Concrete for Different Types of Cement

2019 ◽  
Author(s):  
Beata Łaźniewska-Piekar ◽  
Jacek Gołaszewski
Keyword(s):  
Cement Paste ◽  
Air Entrainment ◽  
Hardened Concrete ◽  
Test Results ◽  
Air Voids ◽  
Air Content ◽  
Air Volume ◽  
Spacing Factor ◽  
Different Types ◽  
The Relationship

Research results of the relationships between air-volume in air-entrained cement paste, mortar and concrete, all designed according to PN-EN 480-1 guidelines are presented in the paper. The cement paste, mortar and concrete, with w/c=0,5 ratio, were prepared using innovative air-entraining cement CEM II/B-V. The air-entraining cement CEM II/B-V was produced using two methods: mixed together with natural or synthetic aerated admixture. The air volume test of the volumetric method was carried out in case of fresh cement paste, mortar and concrete mix. Fresh concretes were evaluated in terms of stability of air entrainment and consistency for 5, 20 and 40 min. The porosity structure parameters, like summarized air-content, specific surface of air voids, air-voids spacing factor and micropores content of hardened concrete, were estimated using computed tomography with a resolution of 2-5 μm. The aim of the research was to determine the dependence between air-content of cement paste, mortar and concrete on the measurement of air-entrainment of cement paste or mortar with the same w/c ratio and type of cement, all designed according to PN-EN 480-1 guidelines. Test results proved that there is a good correlation between the measured air-content of the cement paste, mortar and concrete. Therefore, it is possible to predict the aeration of concrete on the air-entrainment of the mortar.

Determination of Parametres of the Air-Void System in Airfield Pavement Concrete Using Computed Tomography

2017 ◽  
Author(s):  
Danuta Kowalska ◽  
Paweł Iwanowski ◽  
Agata Kowalewska
Keyword(s):  
Computed Tomography ◽  
Air Entrainment ◽  
Image Resolution ◽  
Hardened Concrete ◽  
Polished Section ◽  
Air Voids ◽  
Tomography Method ◽  
Air Void ◽  
Pavement Concrete

Immediately after completion airfield pavements begin a gradual deterioration that is attribute to several factors. One of the major elements contribute to airfield pavement deterioration is exposure to the environment (freezingthawing and de-icing salts). Air-voids microstructure in cement-based materials is an important feature related to the freeze-thaw durability of these materials since all the adverse influences are result of potentially harmful ionic fluids and aggressive gas transport through the concrete and the transport properties strongly depend on the morphology of the pores inside the concrete. For revealing the porous microstructure in airfield pavement concrete X-ray tomography method was used. New and advance methodologies have been developed to determine the basic parameters of air entrainment in concrete (total content of the air, specific surface area of the air-voids system, spacing factor and content of micropores) by summing the distances traversed across a given component along a series of regularly spaced lines in one or more planes intersecting the sample. Using the method mentioned above, to meet requirements of PN-EN 480-11 specification (describes procedure for microscopical determination of air voids characteristics in hardened concrete), the original software was applied – AVCT (Air Void by Computed Tomography) computer programme. The specimens for CT testing were cylinders extracted by drilling out from the investigated concrete core or cubic specimen. The CT method does not require any special processing of the surface of tested specimen as opposed the common method according to PN-EN 480-11, by which the properly polished section is a prerequisite for obtaining proper results of air voids characterization. The paper presents the results of the evaluation of air-voids microstructure in concrete conducted with the application of computed tomography method. Exemplary images of distribution and size of air-voids in concrete specimens have been presented. Special attention was paid to obtain effective image resolution.

Air Entrainment and the Fabrication of Concrete Railroad Ties

2015 ◽  
Author(s):  
Mohammed T. Albahttiti ◽  
Ahmad A. Ghadban ◽  
Kyle A. Riding ◽  
David Lange
Keyword(s):  
Prestressed Concrete ◽  
Air Entrainment ◽  
Vibration Exposure ◽  
Vibration Acceleration ◽  
Manufacturing Plants ◽  
Air Content ◽  
Concrete Properties ◽  
Air Void

Handling and vibration can affect the air content of prestressed concrete railroad ties. The amount and variation in vibration experienced in concrete railroad ties were investigated to determine the concrete fabrication conditions typically used. Two methods of fabrication were investigated by measuring the concrete properties and vibration exposure during placement at two concrete tie manufacturing plants. In addition to measuring the vibration distribution in concrete railroad ties, a pair of ties were selected for hardened-air void analyses to determine any variation of air content in relation to the height of the ties. The vibration results indicate the existence of constructive and destructive wave-interferences in tie cavities. These interferences may contribute to large variations in the vibration acceleration throughout the length, depth, and width of concrete crossties during fabrication. This may account for the air-loss across the depth of the ties.

Precision of the air void characteristics measurement by ASTM C 457: results of an interlaboratory test program

1996 ◽  
Vol 23 (5) ◽  
pp. 1118-1128 ◽  
Author(s):  
François Saucier ◽  
Richard Pleau ◽  
Daniel Vézina
Keyword(s):  
Test Method ◽  
Interlaboratory Study ◽  
Hardened Concrete ◽  
Probability Of Error ◽  
Air Content ◽  
Spacing Factor ◽  
Interlaboratory Test ◽  
Void System ◽  
Concrete Production ◽  
Air Void

Since 1993, the Quebec Department of Transportation requires all its concrete suppliers to demonstrate that their concrete satisfies the requirements of the CSA A23.1 standard as regards the maximum spacing factor of the air void system. This new requirement raises questions about the reproducibility of the ASTM C 457 test method. An interlaboratory study was carried out to verify if the variability of the test method is sufficiently low to allow reliable decisions on the acceptance or rejection of in-place hardened concrete. A total of 18 operators from 13 different laboratories microscopically examined the six concrete slabs used for the study. It is concluded that the average reproducibility coefficient of variation is 14.4% for the total air content measurement and 14.2% for the spacing factor measurement. Considering these results, the probability that the measured value of the spacing factor exceeds the mandatory limit of 230 μm on a concrete production containing an air void system with a spacing factor of 170 μm (the target value proposed in the CSA A23.1 M-94 standard) is less than 0.7% (a probability of error of about 1%, 5%, or 10% is typical of most quality control test methods). Key words: concrete, air content, air void measurement, spacing factor, ASTM C 457 standard, interlaboratory study, freeze–thaw durability.

Experimental Investigation on the Influence of Water-Cement Ratio on Air-Void Parameters of Cement Concrete

2013 ◽  
Vol 771 ◽  
pp. 29-33
Author(s):  
Jin Xi Zhang ◽  
Chao Wang ◽  
Ming Yang Guo ◽  
Mao Cheng Ma
Keyword(s):  
Experimental Investigation ◽  
Hardened Concrete ◽  
Cement Concrete ◽  
Marked Rise ◽  
Air Voids ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water ◽  
Air Void ◽  
The Impact

This paper studies the effect of water-cement ratio [w/ on the air-void parameters of cement concrete, which has a significant influence on the durability of concrete. Based on the experimental investigation, it is found that the impact on the air content of hardened concrete due to different water-cement ratio is not great. Test results also indicate that with the increase of water-cement ratio, the spacing factors also experienced a marked rise, and the mean diameters as well as the specific areas of air voids evidently increased or declined, respectively, which may lead to an adverse effect on the frost resistance of concrete.

scholarly journals Image-based Restoration of the Concrete Void System Using 2D-to-3D Unfolding Technique

2020 ◽  
Author(s):  
Yu Song ◽  
Chuanyue Shen ◽  
Robbie Damiani ◽  
David Lange
Keyword(s):  
Air Entrainment ◽  
Void Size ◽  
Essential Information ◽  
Air Voids ◽  
Freeze Thaw ◽  
Void System ◽  
Void Structure ◽  
Unfolding Analysis ◽  
Air Void ◽  
2D To 3D

Hardened air void analysis provides essential information of concrete freeze-thaw durability based on the size and spacing of air voids in the material. As the physical freeze-thaw experiment is time-consuming and costly, the characteristics of concrete air voids are often deemed as a proxy of the freeze-thaw performance. This analysis is typically done by measuring the 2D air void intersections on polished samples, but the current interpretation of the 2D void characters does not accurately represent the actual void structure in 3D. To solve this problem, a 2D-to-3D unfolding technique has been proposed in the field of stereology. However, the unfolding analysis is known to be sensitive to several factors, such as void population and size along with a binning scheme, where improper unfolding can considerably bias the prediction of the actual concrete void system. This study investigates the optimal strategy of conducting the unfolding analysis for concrete. The investigation is carried out on both idealized void systems to interrogate the influence of the critical factors individually, and real concrete samples with varying levels of air entrainment to assess the concrete-specific impacts. The concrete void system is studied based on a stereological model emulating the intersected 3D air voids on the surface of polished concrete. The results highlight that, for unfolding concrete voids, logarithmic binning scheme is far more accurate to linear binning. The low unfolding error of the concrete samples indicates that the proposed methodology enables an accurate restoration of 3D void size distribution.

scholarly journals Study of the Air-Entraining Behavior Based on the Interactions between Cement Particles and Selected Cationic, Anionic and Nonionic Surfactants

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3514
Author(s):  
Qi Liu ◽  
Zhitao Chen ◽  
Yingzi Yang
Keyword(s):  
Nonionic Surfactant ◽  
Cationic Surfactant ◽  
Cementitious Materials ◽  
Solid Particles ◽  
Air Bubbles ◽  
Air Voids ◽  
Air Entraining Agents ◽  
Air Void ◽  
Positively Charged

The essential role of the air void size distribution in air-entrained cementitious materials is widely accepted. However, how the air-entraining behavior is affected by features such as the molecular structure of air-entraining agents (AEAs), the type of solid particles, or the chemical environment of the pore solution in fresh mortars is still not well understood. Besides, methods to assess the interaction between AEAs and cement particles are limited. Thus, in this study, the air-entraining behaviors of three kinds of surfactant (cationic, anionic, and nonionic) were examined. The general working mechanisms of these surfactants were studied by zeta potential and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Results indicate that the cationic surfactant entrains improper coarse air voids due to the strong electrical interaction between air bubbles formed by the cationic surfactant and negatively charged cement particles. The anionic surfactant interacts with the positively charged part of cement particles, and thus entrains finer air voids. The interaction between the nonionic surfactant and cement particles is very weak; as a result, the nonionic surfactant entrains the finest and homogeneous air voids.

A laboratory investigation for potential durability of ready-mixed concrete retempered for air content and workability

1976 ◽  
Vol 3 (4) ◽  
pp. 570-577 ◽  
Author(s):  
B. W. Langan ◽  
M. A. Ward
Keyword(s):  
Compressive Strength ◽  
Laboratory Investigation ◽  
Hardened Concrete ◽  
Air Content ◽  
Spacing Factor ◽  
Void System ◽  
Air Void ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

The effects of agitation and retempering on some properties of fresh and hardened concrete are considered.Data are presented on the influence of agitation and retempering with an air-entraining agent on the workability, compressive strength, and air void system in hardened concrete.The results indicate that although agitation reduces air content and increases the spacing factor, the original parameters can be regained by proper retempering. It is shown that any loss in compressive strength due to retempering is accompanied by an increase in potential durability due to the improvement of the air void system.

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