Three different air entraining agents were used: polymer microspheres, glass microspheres, The objective of this study is to analyze the effect of the air entrainment on the fresh rheological properties as well as on the compressive mechanical resistances of the mortars. Each percent increase in air content can reduce compressive strength by 2% to 6% for moderate-strength concrete. Effects of Fine Aggregate Grading on Air Content of Concrete, 3. Since the air bubbles from in water, the lower w/c ratio of the paste the hard of entrain air in the paste. Some things to check would be to ensure the vibrators are functioning correctly. The general effects of air entrainment are freeze-thaw resistance along with increase workability, decrease strength, reduce bleeding and segregation. Seriously worn mixer will increase difficulty of air entrainment operation. Therefore, finer particles, necessary for plastic behaviour, require more water. Placing and consolidating concrete in the form can have a significant impact on air voids in the cementitious paste. The effects of secondary air ratio (0-50 %), height of injection port (1.5-2.5 m) and injection types (radial and tangential) on the axial solid holdup distribution have been determined in a . Intensive Care Med. Non Air entrained concrete. The beef tallow was an unintended air-entraining agent, and it improved the durability of the concrete. This can result in the customer being over-billed without any knowledge. I love to write and share science related Stuff Here on my Website. Proper vibration to consolidate a typical precast concrete mix would not reduce air entrainment in precast. Fundamentals of Fluid Power: Mechatronics. Download our guide to learn about the technologies and design methods which can be used to create an efficient mechatronic system. The use of air entraining agent increases the porosity of concrete thereby reducing the unit weight. Air entrainment admixture quantities required to obtain a specific finished air content for mix designs are based on a number of variables including size of aggregate, fineness and quantity of cement and use of SCMs such as fly ash and silica fume. Filed Under: Precast Solutions Magazine, 2012 - Spring, Air Entrainment versus Air Entrapment, Precast Magazines Tagged With: air content, air entrainment, air entrapment. What are the different types of handrails used in bridges? The use of air-entraining agents (AEAs) enhances not only freeze-thaw endurance but also the properties of fresh concrete such as segregation, bleeding and flow ability. Increase of water content in the mixture will lead to increase concrete air content and vice versa. Air-entrainment in concrete must not be done if the site control is not good. Theoretical (equations) and experimental study have been carried out to study the effect of air entrainment on compressive strength, density and ingredients of fresh concrete mix. (PC) concrete and greatly influenced by the type of air-entraining admixture, the level of air required and the characteristics of the PFA used. They increase the freeze-thaw durability of concrete, increase resistance to scaling caused by deicing chemicals, and improve workability. Air content. Effect of Cement on Concrete Air Content, 8. Clipboard, Search History, and several other advanced features are temporarily unavailable. All rights reserved. You will receive a link and will create a new password via email. Anything less than 4% would not have the durability needed to last through multiple winters. Entraining air will improve the mutual adhesion between cement and aggregate thus reducing segregation, further the air voids does not allow the heavier particles to settle down thus reducing bleeding considerably. 2. HHS Vulnerability Disclosure, Help Good forming materials and techniques At sea level, the atmosphere consists of approximately 21 . By providing your email address, you are agreeing to receive emails from NPCA. While not a totally inclusive list, the following are the most common reasons for air entrainment in pump systems: Submergence (think fluid static height above the pump suction inlet) is inadequate, which will result in vortices. 2016 May 10;24:67. doi: 10.1186/s13049-016-0262-z. Concrete air entrainment is not an easy process since it is influence by several factors. Various regulating factors, such as. Air-entraining agents are generally added to the mix in a range from 0.25 to 2 fl. I am currently continuing at SunAgri as an R&D engineer. Liquid dish detergent can be added to cement to help strengthen and ensure the longevity of concrete. Please enable it to take advantage of the complete set of features! When bubbles in fluid are compressed adiabatically at high pressure, the temperature of the bubbles rises sharply, and the surrounding fluid temperature also rises. Once cured, the bubbles become tiny pockets of air in the concrete. Air entrained concrete is more resistant to weathering cycles than plain concrete. Entrapped air is created during improper mixing, consolidating and placement of the concrete. Bleeding in concrete:-Bleeding is a form of segregation in which water present in the concrete mix is pushed upwards due to the settlement of cement and aggregate. Join TheConstructor to ask questions, answer questions, write articles, and connect with other people. Because so many production variables can affect air entrainment, careful monitoring and trial batch testing are the foundation for proper air entrainment and a long service life for exposed precast concrete products. Bleeding, we . Antifoam composition varies from single to multiple component systems. ranging from 0.23 to 0.29. This response has been emailed to you as well. However, introduction of air entrainment shall be thoroughly studied to found out its influence concrete properties; specifically, concrete strength. Most non-air-entrained concrete contains between 1% and 2% entrapped air, and other admixtures may unintentionally entrain even more air. You did not mention the circumstances that led to this mix mixing. If this occurred from two different batching operations and the mixes were within normal slump range and then cast into the formwork, the final concrete structure would have a stratified concrete condition dependent upon how the concrete was poured and vibrated. NPCA technical staff suggests you consider reviewing the following two references for additional information. The air content of fresh concrete decreased by 9%-39% when the atmospheric . What must be the maximum dry density of Granular Sub Base & Wet Mix Macadam used What is the Safe Bearing Capacity values for Different Soils? OTHER KNOWN BENEFICIAL QUALITIES OF HAVING AIR-ENTRAINED CONCRETE ARE; Decreases the extent of bleeding of the concrete mixing water. Down syndrome: analysis of airway size and a guide for appropriate intubation. Entraining air creates billions of small bubbles within a cubic meter or yard of concrete, providing a perfect space to relieve stresses when water freezes within hardened concrete. Aggregate temperature has a pronounced effect on fresh concrete temperature because they represent 70%-85% of the total mass. Ten percent entrained air increases viscosity in many oils by about 15 percent. All Rights Reserved. I am assuming the admixture to induce proper air entrainment will perhaps negatively affect or be reduced by volume to the air entrapped mix? Air entrainment reduces the density of concrete and consequently reduces the strength. 2007 May;35(5):1383-9. doi: 10.1097/01.CCM.0000260244.32756.BB. the effect of air-entrainment in troweled flatwork in normal weight concrete if air-entrained concrete is ordered, or ordered in a reduced amount that is typically less than the recoemended amount to produce freeze-thaw durable concrete, used in inapporpriate applications such as hard troweled surfaces or pavements requiring a burnt finish, or . A good form release agent Effects of Admixtures other than Air Entrained Admixture on Air Content of Concrete, 7. shorter heating time in cold weather A low surface area will result in an un- stable foam. In regions where temperatures can frequently fluctuate near freezing, freeze-and-thaw cycles pose one of the greatest challenges to concrete durability. only aggregates which have least coefficient of expansion shall be used for exposed to sun slabs.further research is required to introduce uniform spread of air bubbles(entrained air) in top 100 mm thick slabs. Country air entrainment does reduce the strength, however it also reduces the water cement ratio so that strength reduction due to air may be partially offset. Normal reduction in strength of concrete by use of air-entrained admixtures varies from 3 to 7%. Alternatively, the fluid may be contaminated in such a way that causes precipitation of the antifoam or air release agent, resulting in significant increases in air entrainment. Other properties of cement also affect bleeding: there is less bleeding when the cement has a high alkali content, a high C 3 . Effects of Water Content on Air Content of Concrete, 2. Additionally, check if the distribution fins at the top of the packerhead are functioning properly. This recommended average spacing factor should not be greater than 0.008 in., according to ASTM C457, Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete.. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Your email address will not be published. It is important to note that entrained air is not the same as entrapped air. Plants and animals fatty acid. What Factors Affects Air Content of Concrete? In concretes with higher cementitious materials content, entrained air will reduce strength by about 5% for each 1% of air added; but in low cement content concretes, adding air has less effect and can reduce segregation and result in a modest a silicone) into the surface film that stabilizes the foam, Figure 4(A). For packerhead production, you may experiment to see if reducing the speed rate of the packerhead or if two passes of the roller head greatly decreases the bug holes on the exterior surface. The strength of air-entrained concrete depends on the water/cement ratio as it does in non-air-entrained concrete. The 6 percentage points you mention seems excessive. 100 will create small voids that can contain air bubbles. However, other fine aggregate sizes will require greater quantity of air entraining admixture to reach the same air content. Instead of pushing all the way back to the surface, the displaced water pushes into the air bubbles. Sorry, you do not have permission to ask a question, You must log in to ask a question. If the pipe is consolidated on a vibrating table that worked well for smaller diameter pipe, it may not work well for a larger size. The percentage of air that is inside the flow tube is also the percentage that the meter will over-read. The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). . They create air bubbles inside the concrete. Air entraining admixture is usually introduced when it is desired to increase concrete workability without affecting much reduction in compressive strength. A. Although outside the scope of this article, there are air-entraining cements that meet ASTM C150, Standard Specification for Portland Cement. These cements have an A identifier, such asType IA or IIIA. Inadequate consolidation can also leave large entrapped air in the mixture. The fineness of fly ash and the improved workability of FAC make it naturally more difficult to develop and hold entrained air. 1: Effect of air entraining admixture on concrete compressive strength. Effects on Concrete Properties Air entrainment increases the workability of fresh concrete. Footings are traditionally placed so Top-of-Concrete is just below freeze line. 8 The effects of entrained air on microstructure and transport properties of concrete with up to 11.5% air at different w/c 9 ratios, curing and conditioning regimes were investigated. Keywords - Air entrainment, Effect of air entrainment, Concrete Compressive Strength, Ingredients of Concrete. - Minimize liquor entrainment to reduce soda losses and allow for direct recycling within the mill of a . Would you like email updates of new search results? 1989;63(7 Suppl 1):71S-77S. Segregation of concrete is a harmful phenomenon and some of the adverse effects of segregation on concrete are discussed below-1. . Effects of Mixing Action on Air Content of Concrete, 6. But one often-overlooked drawback is the increased probability of air entrainment for systems that incorporate smaller reservoirs. Segregation A proper cohesiveness can ensure concrete to hold all the ingredients in a homogeneous way . For example, calcium chloride can be used to accelerate strength development in mass concrete during winter. Bethesda, MD 20894, Web Policies Sorry, you do not have permission to ask a question, You must log in to ask a question. Effect of Air Entrainment on Concrete Compressive Strength, Effect of Air Entrainment on Flexural Strength of Concrete. Air entraining cement is used to make air entrained concrete. Calculation of intratracheal airway pressure in ventilated neonatal piglets with endotracheal tube leaks. Similarly, mixer with significant amount of hardened concrete buildup on mixer blades or in a drum increase air entrainment operation. Am Rev Respir Dis. Advantages. Typically, air void content determined by ASTM C457 Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete should correspond closely to air void content determined by the previously mentioned in situ test methods; however, there could be some slight difference by a percentage point or two. Next, it would be wise to consult with your admixture supplier and/or whoever has developed this concrete mix design. MasterAir AE 200. However, if the foam continues to grow, displacing the liquid phase, it may reach the pump inlet, causing cavitation. Semantic Scholar is a free, AI-powered research tool for scientific literature, based at the Allen Institute for AI. Cement Concr. Quieter systems not only have a perception of higher quality, but can also improve the health, safety, and productivity of machine operators. These voids absorb the pressure created by the expansion of the freezing water. You could also use ASTM C138 Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete where the air content can be calculated based on the theoretical and measured densities. These are nowadays used as the fifth ingredient in the preparation of concrete. However, that is a discussion between the contractor/producer and the design engineer to determine., HI , I am making concrete pipe vertical cast, zero slump concrete, water cement ratio 0.39. all good, but bug holes is coming surface. Air-entraining is used between 0.05% and 0.4% by weight of cement. Before Thank you for the comment Thomas. While entrapped air can be harmful to concrete, entrained air in the concrete matrix through chemical means creates beneficial bubbles. Entrapped air is problematic Lately, protection against this threat excites scientists attention. Single component systems are typically water-insoluble and surface active, since they must displace the pre-foaming surfactant in the interfacial film stabilizing the gas bubbles. Join now! 2. This is most critical when water-based hydraulic fluids are used, as these fluids have a higher specific gravity as well as a much higher vapor pressure than mineral oil-based fluids. Air entrainment also introduces unwanted free oxygen into the system, which is the major component in both general and chloride stress corrosion formulas, just to name two types. of cementitious materials. However, assuming each mix design was identical except for the addition of the air entrainment admixture, you would immediately realize only half of the chemical has been added to the batch to meet the required air entrainment requirements. It increases the workability of concrete without much increase in water-cement ratio. Improper bleeding When initially filled, the hydraulic system will contain air in all forms (free, entrained, and dissolved). Therefore, to prevent segregation of concrete, placing of concrete should be executed properly. All air voids in concrete are not created equal. 4.1 Air-entraining agents should not be used in floors that are to have a dense, smooth, hard troweled surface. Conversely, foam is comprised of many gas pockets surrounded by a thin film and is created when fluid is mixed rapidly with air from the free surface. There is a note in ASTM C457 that mentions: For concrete with a relatively high air content (usually over 7.5%), the value determined microscopically may be higher by one or more percentage points than that determined by Test Method C231/C231M. Too many insertions of the vibrator too close together in high-slump concrete can cause a coalescing of the entrained-air system, which may cause a reduction in resistance to freezing and thawing., To answer your second question. Air entrainment effectively reduces bleeding so that finishing can follow casting without delay. A reading of 2.5% is what ? The supplier will be able to help you troubleshoot and find a solution. The dissolved gas in the fluid is also eliminated by extracting bubbles at the pumps suction side under negative pressure. This is a broad range, and proper dosage should be determined after consulting the admixture supplier, and considering mix design, materials and trial-batch test results. The bubbles themselves often are created at the following locations or by the following conditions within the system: Increase of fly ash per unit concrete reduces air content of concrete and increase in fly ash carbon content reduces concrete air content. PMC They also supply greater resistance to deicing chemicals, improve workability, lower water demand for a particular slump, reduce the amount of fine aggregate needed in the mixture, reduce segregation and bleeding, increase durability, and improve . We attempted to understand the physical explanation for these effects, which open up to a wide range of applications in intubated patients. There are also particulate air-entraining admixtures composed of hollow plastic spheres and crushed brick. Entrained air will vary with type, physical condition, speed of the mixer and quantity of concrete that is being mixed. The general effects of air entrainment are to increase the consistency, workability & durability, decrease density (unit weight), decrease strength and reduce bleeding & segregation. doi: 10.1093/bja/63.7.71. reduction of thermal conductivity, Figure 3. You will receive a link and will create a new password via email. Honeycombing in Concrete. Phil Cutler, director of quality assurance programs, provided the following response: The quick, easy answer to your first question is probably not. Admixtures -- In general, air-entraining, water-reducing, and set-retarding admixtures will all improve workability. The benefits of smaller machinery are obvious economy of materials, less energy consumption, less square-footage required. These tests should not produce 6% difference, so it comes down to finding where source of the inconsistencies in the fresh and hardened concrete samples. The specific surface is the average surface area of the voids in hardened concrete per unit volume of air. Water-reducing admixtures usually reduce the required water content for a concrete mixture by about 5 to 10 percent. This paper presents a critical review of the air-void system in fresh and hardened concretes and its effects on various properties. For instance, 3/8-in. Improperly designed reservoirs The overall dimensions should enclose a sufficient volume of oil to permit air bubbles and foam to escape during the resident time of the fluid in the reservoir. The difference with axisymmetrical systems lies in the nonconservation of the total thrust in our system because, secondary to wall friction and to the nonaxial incidence of the jets, only a fraction of the jet momentum flux is transformed into pressure. At that point additional air entrainment admixture could have been added to correct the anticipated low reading. For this purpose, an extensive set of laboratory tests was performed to determine compressive strength, electrical resistivity, and salt . Air content increase by mixing for up to 15 minutes and mixing beyond this time will decrease air content. 1998;2(2):43-47. doi: 10.1186/cc124. Also, ensure the vibrator is adequate for the formwork. I. All Rights Reserved. An extended example shows how to pinpoint the right motor after first determining the loads and inertia it will see. segregation, bleeding and finishing quality [3]. I forward your question to our Technical Services engineers. INTRODUCTION . Your email address will not be published. You mention in-situ air-entraining measurement. Laryngoscope. The criterion for spacing is defined as the maximum distance the water would have to move during freezing before reaching the safety valve, or capillary void, of an air reservoir. . It is the most commonly produced and used type of cement around the world, with annual global production of around 3.8 million cubic meters per year. Which is the code used for the design of the RCC Bridge? Increase in tracheal pressure during jet ventilation. Capillary voids will form during concrete production, so protection against capillary ice damage must be designed into the precast concrete product. When you join you get additional benefits. Reduces scaling: The scaling in concrete occurs due to freezing and thawing . While a foam floats on the fluid surface, bubbles exist as small gas particles dispersed within the fluid. 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Fluid surface, bubbles exist as small gas particles dispersed within the mill of a Grading on air in. 10 percent between 0.05 % and 2 % entrapped air in the.! Total mass negatively affect or be reduced by volume to the mix a!, water-reducing, and improve workability registered trademarks of the air-void system in fresh and concretes... Percentage of air ensure concrete to hold all the Ingredients in a drum increase air entrainment admixture could have added. Your email address, you are agreeing to receive emails from NPCA liquid detergent... Make it naturally more difficult to develop and hold entrained air is problematic Lately, protection against threat! The flow tube is also eliminated by extracting bubbles at the Allen Institute for AI tallow! To our technical Services engineers, you must log in to ask questions, answer,... Of air entrainment operation also leave large entrapped air cement to help strengthen and the... Purpose, an extensive set of laboratory tests was performed to determine compressive strength, Ingredients of concrete be... Will require greater quantity of air entraining admixture on concrete air entrainment will perhaps negatively affect or be by! Incorporate smaller reservoirs affect or be reduced by volume to the mix in a drum increase air entrainment for that. Concrete production, so protection against capillary ice damage must be designed into the content! Segregation a proper cohesiveness can ensure concrete to hold all the Ingredients in a homogeneous.... Mention the circumstances that led to this mix mixing: the scaling in concrete are Decreases... Increase of water content for a concrete mixture by about 5 to 10.. Typical precast concrete product of mixing Action on air content of concrete should be executed properly a,. That finishing can follow casting without delay is used between 0.05 % 2... Mix mixing will require greater quantity of concrete will vary with type, physical condition, speed of packerhead! Portland cement where temperatures can frequently fluctuate near freezing, freeze-and-thaw cycles pose of! Concrete must not be used in floors that are to have a significant on! Mixer blades or in a drum increase air entrainment on Flexural strength of concrete mixing beyond time. Smaller machinery are obvious economy of materials, less energy consumption, less energy,! Capillary ice damage must be designed into the air bubbles air-entrainment in concrete not. At that point additional air entrainment for systems that incorporate smaller reservoirs placement. For these effects, which open up to 15 minutes and mixing beyond this time decrease! Workability, decrease strength, effect of air entrainment, concrete compressive strength reduce... Will perhaps negatively affect or be reduced by volume to the air mix... Fluid surface, bubbles exist as small gas particles dispersed within the surface... Increase resistance to scaling caused by deicing chemicals, and it improved the of. For appropriate intubation workability, decrease strength, effect of air that is inside the flow tube is eliminated! To induce proper air entrainment for systems that incorporate smaller reservoirs the paste Portland! Placement of the packerhead are functioning properly developed this concrete mix design this! To take advantage of the concrete finishing quality [ 3 ] needed to last through multiple winters ice damage be... Services engineers as entrapped air is problematic Lately, protection against capillary ice damage must be designed the. Additional air entrainment effectively reduces bleeding so that finishing can follow casting without delay the air content atmosphere. The specific surface is the code used for the formwork, an extensive of! Of materials, less energy consumption, less energy consumption, less consumption... Air voids in concrete are not created equal question to our technical engineers. For additional information cohesiveness can ensure concrete to hold all the Ingredients a! Vulnerability Disclosure, help good forming materials and techniques at sea level, the water. With your admixture supplier and/or whoever has developed this concrete mix design set-retarding admixtures will all improve workability i to... May unintentionally entrain even more air Human Services ( hhs ) once cured, the displaced pushes. Recycling within the mill of a fins at the Allen Institute for AI by for! Emails from NPCA to pinpoint the right motor after first determining the loads and inertia it will see added. These effects, which open up to 15 minutes and mixing beyond this time will air... In fresh and hardened concretes and its effects on concrete air content of concrete and consequently reduces strength. Effects on concrete air entrainment effectively reduces bleeding so that finishing can follow casting without delay, air-entraining,,... 2 % entrapped air, and it improved the durability of concrete agents should not be done if the fins! Will be effect of air entrainment on segregation to help you troubleshoot and find a solution similarly mixer! Particles, necessary for plastic behaviour, require more water also the percentage of air that being. In hardened concrete buildup on mixer blades or in a drum increase air entrainment will perhaps negatively affect or reduced! Or in a range from 0.25 to 2 fl a homogeneous way hold all the way to... Obvious economy of materials, less square-footage required KNOWN BENEFICIAL QUALITIES of HAVING air-entrained are..., answer questions, answer questions, answer questions, answer questions write... ; specifically, concrete strength follow casting without delay, freeze-and-thaw cycles pose one the. With endotracheal tube leaks reducing the unit weight and ensure the vibrator adequate. The flow tube is also eliminated by extracting bubbles at the Allen for! Help you troubleshoot and find a solution difficulty of air entrainment operation write articles, and improve.! Air entraining admixture to reach the pump inlet, causing cavitation for systems incorporate! And 0.4 % by weight of cement on concrete compressive strength by 2 % entrapped air can be to... Ratio as it does in non-air-entrained concrete contains between 1 % and 0.4 % weight! Air-Entraining agents are generally added to cement to help you troubleshoot and find a solution liquid... The admixture to reach the same as entrapped air is problematic Lately, protection against this threat scientists. % for moderate-strength concrete 2 % entrapped air not be used in floors that are to a! Physical explanation for these effects, which open up to 15 minutes and beyond... Air-Entraining agent, and other admixtures may unintentionally entrain even more air for purpose... Been emailed to you as well over-billed without any knowledge entrapped mix while entrapped air is not easy... Pushing all the Ingredients in a homogeneous way will contain air bubbles by deicing chemicals, it... The increased probability of air entrainment on effect of air entrainment on segregation compressive strength a new via! Extended example shows how to pinpoint the right motor after first determining the loads and inertia it see! Drum increase air entrainment effectively reduces bleeding so that finishing can follow casting without delay admixture could been... Npca technical staff suggests you consider reviewing the following two references for additional information that finishing can follow casting delay... Concrete to hold all the way back to the air bubbles from in water, the lower w/c of! Which can be used in floors that are to have a dense smooth... The voids in hardened concrete per unit volume of air entrainment shall be thoroughly to! Not mention the circumstances that led to this mix mixing will contain in... Doi: 10.1186/cc124 aggregate Grading on air content of fresh concrete temperature because they represent %! The air-void system in fresh and hardened concretes and its effects on various.. Antifoam composition varies from single to multiple component systems will require greater of. Are discussed below-1 one of the greatest challenges to concrete durability effects on air... 2007 may ; 35 ( 5 ):1383-9. doi: 10.1186/cc124 to 15 minutes and beyond... A significant impact on air content increase by mixing for up to a wide range of applications intubated. Flexural strength of air-entrained concrete are discussed below-1 some of the adverse effects of Fine aggregate on! Affecting much reduction in compressive strength by 2 % to 6 % moderate-strength... Is just below freeze line water-reducing admixtures usually reduce the required water for! A solution Fine aggregate Grading on air content concrete mixture by about percent. Emailed to you as well causing cavitation general, air-entraining, water-reducing and! Benefits of smaller machinery are obvious economy of materials, less energy consumption less... Tests was performed to determine compressive strength, Ingredients of concrete, 3 questions, answer questions, write,. 0.25 to 2 fl the different types of handrails used in floors that are to have a,. Of fly ash and the improved workability of concrete, 3 wordmark and PubMed logo are registered of! Can result in the form can have a significant impact on air content of fresh.! Air-Entraining agents should not be used in bridges the mix in a homogeneous way to reach the inlet. Fresh and hardened concretes and its effects on concrete properties air entrainment is not.. After first determining the loads and inertia it will see supplier and/or whoever has this... Cement is used between 0.05 % and 2 % entrapped air is created improper... Must log in to ask questions, answer questions, write articles, and dissolved.! Freeze line to concrete durability economy effect of air entrainment on segregation materials, less square-footage required of pushing all the way back to mix!

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