The lubrication required for handling concrete without segregation, for placing without loss of homogeneity, for. Provided the cement conforms with the appropriate standard and it has been stored correctly i. Consistency, mobility and compactability define workability. Rich concrete mix high cement content is more workable because the correct lubrication for easy movement would result in more workability due to ample cement aggregates. Aggregatecement ratio is an important factor influencing workability.
Workability of concrete civil engineering community. All the materials and processes involved in producing concrete affect the workability of concrete. Various factors affect the workability cement concrete. Different test methods for workability measurement depending upon the water cement ratio in the concrete mix, the workability may be determined by the following three methods. Effect of rice husk ash on workability and strength of concrete abstract rice husk ash rha is an agricultural waste which is a pozzolanic material that can be blended with the cement for manufacturing concrete. Cohesion and handling properties in bedding mortars. The fresh properties of concrete workability construction essay. To investigate the paste consistency of cement plus pfa. Size of aggregates for a wider substrate, smaller particles need more heat, and incorporating finer particles takes more water to make it workable.
Compaction factor test of concrete for low workability. Factors affecting workability of concrete civil snapshot. By the researchs done in overseas, pfa is known as the admixtures that can improve the workability. This factor is the fineness of the cement particles themselves and their positive effect on concrete workability. What are factors affecting workability of fresh concrete. Properties of highworkability concrete with recycled. Presence of admixtures such as pozzolana or plasticizers increases the workability and strength of concrete. Factors affecting the workability of concrete factors affecting the workability of concrete are materials such as water content, cement content, sand and aggregate properties such as size, shape, grading, mix design ratio and use of admixtures. There are many factors that can affect the strength of concrete.
Slump test suitability this method is suitable only for the concrete of high workability. The slump value of a superplasticized concrete may also be affected on account of other admixtures used concurrently in concrete such as airentraining agent, fly ash, slag or silica fume. Concrete is a composite consisting of matrix and aggregates. The higher the water content per cubic meter of concrete, the higher will be the fluidity of concrete, which is one of the important factors affecting workability. The term is applied broadly to almost every facet of life, although it is increasingly being used in the context of human sustainability on earth. Highly workable concrete can easily be mixed, placed and transported. Workability of the concrete depends on a number of interrelating factors.
Mix must be designed to ensure cohesion and prevent segregation and bleeding. Aug 14, 20 this book is a successor to the authors highly successful workability of concrete published in 1976 and, again, is written specifically for practising engineers and concrete technologists. The strength of concrete is affected by various factors including its ingredients, environmental factors, postprocesses or works, and so on. When a section is narrow, complicated, several narrow corners, inaccessible parts. Factors affecting strength of concrete the constructor. These are the effect of superplasticizers on workability of fresh concrete. The fresh concrete workability mainly depends on water content, cement content, aggregate particle size distribution and amount of hydration and can be modified by adding chemical. The workability of concrete mix is also affected by the temperature of concrete and hence by the ambient temperature. On a hot day, it becomes necessary to increase the water content of the mix in order to maintain the desired workability. For a long time, concrete was considered to be very durable material requiring a little or no maintenance. Two evaluations were conducted to assess the impact of current techniques to manage slump loss as compared to that of the new workability retaining admixture. Factors affecting the workability of concrete are materials such as water content, cement concrete, sand and aggregate properties such as size, shape, grading, mix design ratio and use of admixtures. Slump test compaction factor test veebee consistometer test 1. Due to this all the properties of concrete, whether in fresh.
It has been found that concrete made of round grain sand is more workable than the concrete of crushed sand. Strategies for the improvement of the cement workability. For dense concrete it is essential that the coarse and fine aggregates be well graded, giving the maximum packing density. Concrete workability defines how smoothly freshly mixed concrete is amalgamated, arranged, compacted and finished by. This mixture, when properly proportioned, is at first a plastic mass that can be cast or molded into a predetermined size and shape. Common workability tests are the slump test, compaction factor test, flow test, vebe test, and other field tests like the kelly ball test, and the ktester probe.
Factors affecting selection of construction equipment. The workability of fresh concrete is thus a composite property. To the end this paper, presented by we students will show the result of effect of water content on workability of concrete. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design.
The slump ranged from 255 to 275 mm, which indicate a high workability of concrete. Workability the function of water is also to lubricate the concrete so that the concrete can be compacted with specified effort forthcoming at the site of work. Workability of concrete types and effects on concrete strength. Strength and workability characteristics of concrete by using. Durability of concrete factor affecting durable concrete. Nature of aggregate particles shape, surface texture, porosity etc. Concrete strength is affected by many factors, such as quality of raw materials, watercement ratio, coarsefine aggregate ratio, age of concrete, compaction of concrete, temperature, relative humidity and curing of concrete. Higher watercement ratio weakens concrete and leads to excessive bleeding. Compaction factor test workability of concrete compaction factor test is designed in such a way that it can be used only in laboratory but in some cases, it can be used for field concrete tests. The quantity of cement used in the concrete mix is a major factor affecting the durability of concrete.
Workability of fresh concrete by compacting factor test. The useful internal work is a physical property of concrete and is the work or energy required to overcome the internal friction between the individual particles of the mixture. Sustainability, in its simplest form, is the capacity to endure. An increase in watercement ratio increases the workability of concrete. There is another factor to take into account when considering workability of concrete. Workability, testing, and performance of selfconsolidating concrete article pdf available in aci materials journal 963.
Workability is one of the physical parameters of concrete which affects the strength and durability as well as the cost of labor and appearance of the finished product. There are certain factors that will affect the workability of concrete. Here is a list of factors that affect the selection of ce and should always be kept in mind. Its use can reduce the environmental impact of the cement industry. A lower water cement ratio means less water, or more cement and lower workability. The concrete workability is primarily dependent on the materials use in concrete mix, their mix proportions and the environmental conditions. Durability of concrete depends upon the following factors. The elements affecting the workability of concrete can be list as follows. The type of aggregate and the size of the aggregate particles can also influence the tensile strength. Or the internal work done required to overcome the frictional forces between concrete ingredients for full compaction. At the more workable end of this group, concrete may be compacted in certain cases with handoperated machines. The compacting factor test has been developed at the road research laboratory in united kingdom.
Increasing aggregate size increases the strength of the concrete. A concrete is said to be workable if it is easily transported, placed, compacted and finished without any segregation. Since the early 20th century, the concrete industry has recognized the need to monitor concrete workability to ensure that concrete can be properly placed and can achieve adequate hardened strength. This objective then can be divided into more small objectives by dividing it into the experiment that will be done which are. A myriad of test procedures for determining workability have been developed for research, mix proportioning, and field use. Workability is the ease with which concrete can be mixed, transport,place, compacted and finished or it will be referred as ease with which we can work with the concrete. What are the factors affecting workability of concrete. Apr 14, 2018 this video explains the concept of factors affecting workability of concrete.
It incorporates the results of a further 15 years research and develops the treatment of workability as a property to be measured in terms of two. Fresh concrete stiffens with time and loss workability though it is not exactly settling or getting strength at all. The lower slump concrete with the additional cement is just as workable as the normal concrete. There are four factors that can affect the workability are. Introduction from a practical point of view the workability of cements is measured in mortar through the flow. The relative proportions of the fine and coarse aggregates in a concrete mix are one of the important factors affecting the workability and strength of concrete. The higher the water content per cubic meter of concrete, the higher will be the fluidity of concrete, which affect the workability. If the cement content used is lower than the required, then the watercement ratio. Request pdf factors affecting the workability and strength of alkaliactivated high calcium fly ash concrete the effects of several parameters on the workability and strength of alkali. However if the workability becomes too low the concrete becomes difficult to compact and the strength reduces. Desirable workability depends on two factors which are. It is obvious that no single test can evaluate all these factors.
Concrete workability defines how smoothly freshly mixed concrete is amalgamated, arranged, compacted and finished by keeping the conformity as it is. Resistance to freezethaw action in the hardened concrete. Water content, aggregate properties, use of admixtures, fineness of cement are the factors affecting workability. Properties of concrete workability, setting, bleeding. Water cement ratio has much effect in the workability. Procedure to determine workability of fresh concrete by compacting factor test. Concrete test factors affecting workability of concrete. Factors affecting the workability of concrete are materials such as water content, cement content, sand and aggregate properties such as size, shape, grading, mix design ratio and use of admixtures. There are other factors that affect concrete permeability, but are not as influential as those discussed above. Factors affecting workability of concrete civil engineering. Compaction factor test workability of concrete the.
The coarse aggregate used in the experimental investigation is a mixture of 20mm and 10mm size aggregates. Each and every process and materials involved in concrete mixing affects the workability of concrete. Unworkable concrete needs more work or effort to be compacted in place, also. Influence of aggregate characteristics on workability of superworkable concrete article pdf available in materials and structures 491 january 2015 with 1,499 reads how we measure reads. Factors affecting workability a water content b mix proportions c size of aggregates d shape of aggregates e surface texture of aggregate f grading of aggregate g use of admixtures. The diverse requirements of transportability, compatibility, mobility, stability, mixability, placeability, and finish ability of fresh concrete mentioned above are collectively referred. If cement is reduced, then at fixed wc ratio the workability will be reduced leading to inadequate compaction.
Water content, aggregate properties, use of admixtures, fineness of cement are. Introduction of concrete concrete is a mixture of sand, gravel, crushed rock or other aggregate held together by a hardened paste of cement and water. High strength concrete is characterized by a dense interfacial transition zone itz and behaves differently from low strength concrete. The workability of a concrete mix gives a measure of the ease with which fresh concrete can be placed and compacted. Workability of concrete is measured in terms of the ease of mixing and placing of concrete. Suresh professor, nie, mysore the behavior of green or fresh concrete from mixing up to compaction depends mainly on the property called workability of concrete.
Workability is often referred to as the ease with which a concrete can be transported, placed and consolidated without excessive bleeding or segregation. Permeability declines as the concrete age increases because pores would be filled by hydration product. Workable concrete shows very less internal friction between particles and overcomes the frictional resistance with just the amount of compacting efforts provided. At the worksite, supervisors who are not well versed with the practice of making good concrete, resort to adding more water for increasing workability. Water content will have important influences on the workability in given volume of concrete. Workability is also the ability of fresh concrete to fill formwork properly with a sufficient amount of vibration and without reducing the concrete s quality. Considering important sustainability factors with concrete. Analysis of workability of concrete by using superplasticizer. Factors affecting permeability of concrete civil snapshot. Workability of concrete factors affecting workability. Economic considerations such as the cost of owning the equipment and operation and fuel costs are some of the most important factors that play a deciding role in selecting the equipment. Workability improves with the increase in water content in concrete and vice versa.
It is difficult to define precisely all the aspects of the workability in a single definition. Sampling concrete mix m15 is blended according to the specified mix design in the laboratory. Factors affecting workability of concrete free download as pdf file. The test data also show that the water content in the concrete mix plays an important role. Research paper relation between workability and compressive. Effect of rice husk ash on workability and strength of concrete. Generally, the watercement ratio is inversely proportional to the strength of concrete, the same watercement ratio, by increasing the amount of cement to increase the strength of concrete is false, then only increase the workability of concrete, increases concrete shrinkage and deformation.
Higher watercement ratio is generally used for manual concrete mixing to make the. If air entraining admixture is used in the mix, it will also increase the workability and decrease segregation and bleeding. Concrete products the impact of workability retention. Each factors and their influence on concrete workability are mentioned briefly. Workability of concrete factors affecting workability of concrete.
Workability, consistency, mobility, compactibility, crushed. Rounded aggregates give more workability to concrete. Workability of concrete increases with increase in water content. For example, age of concrete, cement properties, aggregate, use of admixtures, and loss of mixing water.
Factors such as constituent materials and environmental conditions affect workability. The factors that affect the workability of concrete are size distribution of the aggregate, shape of the aggregate particles, gradation and relative proportions of the fine and coarse aggregate, plasticity, cohesiveness, and consistency of. Higher the water content per cubic meter of concrete, the. The amount of water content available in a volume of concrete will have a significant effect on the workability of concrete.
Factors affecting the workability of concrete are materials such as water. The first step taken by the research team in pursuit of a fieldusable approach to measuring concrete workability was to gather information on factors affecting concrete workability and on test methods and equipment that have existed, been described in the past, or are currently in use. Strength and workability characteristics of concrete by using different super plasticizers. The prime factor for bleeding in concrete is the high dosage of water cement ratio. Effect of superplasticizers on workability of fresh concrete. Voids in concrete can be filled with air or with water. Workability of concrete definition factors affecting. The temperature and relative humidity also affect the result. In this study, the slump flow varied in the range of 505620 mm. Durability of concrete types of durability and factors.
Workability of fresh concrete the strict definition of workability is the amount of useful internal work necessary to produce full compaction. Factors affecting workability of concrete construction aggregate. Water content mix proportions size of aggregates shape of aggregates. Workability refers to a property that directly affects strength, quality, appearance, as well as the cost of labor for placement and finishing operations. The concrete should flow readily into the form and go around and cover the reinforcement, the mix should retain its consistency and the aggregates should not segregate. The relative quantities of cement, aggregates and water mixed together, control the properties of concrete in wet state as well as in hardened state. Factors affecting workability of concrete a concrete is said to be workable if it is easily transported, placed, compacted and finished without any segregation. Normal bleeding is quite good, and it enhances the workability of concrete. The slump flow results also reveal that the concretes were highly workable. Compaction of low workability mixes including semidry concrete. Important chart on concrete factors like workability, slump.
For better workability fine and coarse aggregates should be well graded. When the section is crowded with steel reinforcement and. What are the factors affecting the workability of concrete. Due to this all the properties of concrete, whether in fresh state or hardened state, is affected by these ingredients and their proportions. The term workability indicated the ease or difficulty with which the concrete is handled, transported and placed. Slump test doesnt give accurate results for the low workability of concrete when the slump is factor test used for concrete mixes of very low workability. This test consists of a vibrating table, a metal pot, a sheet metal cone, a standard iron rod. The higher the water content per cubic meter of concrete the higher. Factors affecting workability of concrete workability of concrete is measured in terms of the ease of mixing and placing of concrete. For high strength concrete, as low wc is to be maintained, the workability should be achieved by use of admixtures, such as water reducers and airentrainers. Concrete is said to be workable when it is easily placed and compacted homogeneously i.
The word workability defines an amalgam and composite of four concrete flowmaking physical properties like mixability, transportability, mouldability, and compatibility you cant ignore this physical parameter because of the fact that it effects the strength, durability, cost of labor, compaction effort, and also the final appearance. High workability concrete generally provides a slump higher than 200 mm and a slump flow greater than 500 mm 32. The product is added separately to provide workability retention without impacting initial workability and negatively affecting setting time or early compressive strength. Factors affecting strength of concrete civil engineering. Pdf influence of aggregate characteristics on workability. Workability of concrete factors affecting workability of. More the water cement ratio more will be workability of concrete. The compacting factor test is designed primarily for use in the laboratory but it can also be used in the field. Following are the important properties of fresh concrete. To assess the workability of concrete using compaction factor test apparatus compaction factor apparatus trowels hand scoop 15. Various factors affect the workability cement concrete workability of concrete.
This method is very suitable for very dry concrete whose. The factors that affect the workability of concrete are given below. Coarseness workability consolidation a new approach. Higher workability concretes are easier to place and handle but obtaining higher workability by increasing water content decreases strength and durability. Sep 03, 2016 concrete or plastic concrete is a freshly mixed material which can be molded into any shape. The quality of concrete satisfying all these requirements is termed as workable concrete. It is more precise and sensitive than the slump test and is particularly useful for concrete mixes of very low workability and normally used when concrete is to be compacted by vibration.
Air voids are on obvious and easily visible example of pores in concrete. Factors affecting concrete strength online civilforum. Pdf on jan 19, 2019, pawan bhattarai and others published effect of water content on. The bleeding in concrete is not harmful if the rate of evaporation of water is equal to the rate of bleeding. Segregation and bleeding in concrete causes, effects. The start of curing of geopolymer concrete at elevated temperatures can be delayed at least up to 60 minutes without significant effect on the compressive strength. Factors affecting the tensile properties of concrete. Increased cohesion, reducing the tendency to bleed and segregation in the plastic concrete. High mixes of concrete give more workability to concrete as more cement gives more paste of cement for lubricating the concrete. The time required for the shape of concrete to change from slump cone shape to cylindrical shape in seconds is known as vee bee degree. What are the factors affecting the durability of concrete.
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