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Marsh cone test
The Marsh cone test is a reliable method for assessing the rheological properties of cements and mortars, indicating viscosity through flow time. It involves measuring the flow of cement paste through a cone-shaped vessel, with variations based on water-to-cement ratios and super plasticizer dosages. The results help determine the optimal super plasticizer content for concrete, facilitating better compatibility and mix design.
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Marsh cone test
- 1. MARSH CONE TEST BY BY: AKSHAY R MANOHAR 1 sem MTech(Construction Technology) CIVIL ENGINEERING DEPT. NMAMIT-NITTE.
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- 3. Marsh Cone Test • Marsh cone test is reliable and simple method to study the rheological properties of cements and mortars. • Flow time of cement/mortar through marsh cone is indicator of viscosity, which depends upon cement super plasticizer compatibility. • It is widely used to study cement super plasticizer compatibility and to determine optimum super plasticizer dosage of a specific cement-super plasticizer combination.
- 4. Apparatus • It’sconsist of a conical brass vessel held on a wooden stand with an orifice of 8mm at its bottom. • A stop watch is needed to measure the time taken by 1 litre of cement or mortar to pass through the vessel. • A mortar mixer is also needed to prepare the cement paste with desired w/c ratio.
- 6. PROCEDURE • 1Lof cement paste is prepared in mortar mixer using 2 kg of cement and w/c ratio of 0.32-0.35.High strength Concrete designs typically have w/c ratios less than 0.35. • Water is added in two steps- 70% of water is added in beginning of mixing and rest 30% of water is mixed with super plasticizer, and added afterwards. • Cement slurry is prepared with the w/c ratio of 0.32 and admixture dosage of 0.5 %. • 1 litre of cement slurry is made to flow through marsh cone after 5 min and 60 min of mixing and time in seconds is measured using a stopwatch. • The procedure is repeated gradually increasing the S.P. Dosage in steps of 0.2%. • Similar tests are conducted for rest of super plasticizers and graphs are plotted with time as Y axis and S.P. dosage as X-axis.
- 7. TYPICAL MECHNICAL MIXER MECHANICAL MIXER
- 8. The saturation dosageof super plasticizer can be defined as that point beyond which there is no significant decrease in the flow time.
- 9. Variable parameters •W/c ratio • Temperature(5-45 ‘C) • Admixtures (super plasticizer, retarder, accelerator, Air-entraining admixtures, new generation super plasticizer.)
- 10. Figure 2 showsplots of the flow time at 5 and 60 min, for super plasticizer dosages ranging from 0.4% to 2.0% of the mass of the cement.
- 11. EFFECT OF TEMPERATUREON THE FLUIDITY OF SUPER PLASTICIZED CEMENT PASTE Polycarboxylate Derivatives (PCE based) Sulfonated naphthalene-formaldehyde condensates (SNF)
- 12. Significance • Thesaturation dosage of super plasticizer can be defined as that point beyond which there is no significant decrease in the flow time. • Saturation point can be taken as the maximum super plasticizer content to be used in concrete. • We can implement to use specially recommended admixtures at recommended dosages for given mix design.
- 13. ADMIXTURES • SUPERPLASTICIZER • RETARDER • ACCELERATOR • AIR-ENTRAINING ADMIXTURES • For the above all admixtures marsh cone test can be adopted.
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