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8 Factors that Affect the Workability of Fresh Concrete Lubricating nature of workable concrete is the most important nature Workability is dependent on the proportion of the constituent material as well as on their individual characteristicsCEMEX TB Effects of Water Additions to Concrete The Effects of Water Additions to Concrete proportioned concrete mix should possess Cementitious Material Ratio and Compressive Strength of Concrete
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Water content is the single most important factor affecting workability or the ease of mixing and placing concreteThe effect of these changes is an overall loss of concrete strength The above effects are typical of attack by solutions of sodium sulfate or potassium sulfate Solutions containing magnesium sulfate are generally more aggressive for the same concentration
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Factors which affect the strength of concrete Water Cement Ratio Water cement ratio is one of the most important factors which govern the strength of concrete Water cement ratio is the weight of water in proportion to weight of cement expressed in terms of percentageThe main reason with the concrete s strength and setting time is not really the air temperature but the concrete temperature During the time of cement hydration it sucks up water and forms crystals around the aggregate particles as shown in fig 1 The crystals grow faster but do not have time to grow strong when it is hot and is rap The 28 day strength suffers even though early strength is
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Effect of Curing Methods on Density and Compressive Strength of Concrete It is a known fact that many other factors affect the development of strength of concrete and consequently its durability other than curing or the curing technique applied These factors include quality and quantity of cement used in a mix grading of aggregates maximum nominal size shape and surface texture of Concrete tests can measure the plastic unhydrated properties of concrete prior to and during placement As these properties affect the hardened compressive strength and durability of concrete resistance to freeze thaw the properties of workability slump/flow temperature density and age are monitored to ensure the production and placement of quality concrete Depending on project
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Effect of moist curing time on strength gain of concrete Gonnerman and Shuman 219 HOME PAGE The most effective method for curing concrete depends on the materials used method of construction and the intended use of the hardened concrete For most jobs curing generally involves applying curing com pounds or covering the freshly placed and finished con crete with impermeable Mixture Proportions of Concrete The normal concrete was prepared based on water cement ratio of 050 and a cement content of 340kg/m 3 to obtain a compressive strength greater than 20N/mm 2 at 28 days Immersion method of curing
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Higher curing temperatures promote an early strength gain in concrete but may decrease its 28 day strength Effect of curing temperature on compressive strength development is presented in Figure 2 Figure 2 Effect of Curing Temperature on Compressive Strength There are three main functions of curing 1 Maintaining mixing water in concrete during the early hardening process Ponding and Effect Of Different Curing Methods On The Kolo Stephen Sunday for sharing his research on Effect Of Different Curing Methods On The Compressive Strength Of Concrete the factors affecting it
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EFFECT OF CURING METHODS ON THE COMPRESSIVE STRENGTH OF CONCRETE T James A Malachi EW Gadzama concrete during cement hydration High curing temperature up to 212 F or 100 C generally accelerates cement hydration and concrete strength gain at early age Cur ing temperature below 50 F 10 C are not desirable for early age strength development When the Admixtures are those ingredients in concrete other than portland cement water and aggre gates that are added to the mixture immediately before or during mixing Fig 6 1
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Therefore concrete losing its mix water to the “thirsty” aggregates during the curing process can cause color variation mottling and “surface crazing ” small networks of surface cracks that occur during the early drying process It’s important to keep track of all the mix water added and keep it in the proper range so as not to adversely affect the density of concrete as well as Concrete cures no matter what It is how you treat the concrete during the curing process that will determine the quality of the concrete once it has cured Concrete crystals grow within the matrix of concrete from the reaction between Portland ce
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strength of concrete Repeated cycles of freezing and thawing can result in cumulative damage in the form of Role of Air Content For over 50 years entrained air has been deliberately incorporated in con crete mixtures to reduce damage due to cycles of freezing and thawing Air entraining admixtures or agents are used to produce a stable system of PL981 Return To Index Concrete Technology lizes bubbles formed during the mixing process enhances the incorporation of bubbles of various sizes by lowering the surface tension of the mixing water impedes bubble coalescence and anchors bubbles to cement and aggregate particl Anionic air entraining admixtures are hydrophobic repel water and are electrically charged nonionic or no charge admixtures are also available The
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Size effect and strength correction factors 59 difference between the strengths of concrete specimen with variable h/d ratios Gonnerman 11 experimentally showed that the ratio of the compressive failurePresence of voids in concrete reduces the density and greatly reduces the strength 5 of voids can lower the strength by as much as 30 Slump Test can be used to find out the workability of concrete
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strength of the concrete Moreover the water demand in concrete is decrease by Moreover the water demand in concrete is decrease by the addition of PFAThe use of superplasticizers may produce high strength concrete compressive strength up to 22 000 psi Superplasticizers can also be utilized in producing flowing concrete used in a heavy reinforced structure with inaccessible areas Requirement for producing flowing concrete is defined in ASTM C The effect of superplasticizers in concrete flow is illustrated in the chart below
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