Marsh cone test
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Transcript of Marsh cone test
MARSH CONE TEST
BY BY:
AKSHAY R MANOHAR1 sem MTech(Construction Technology) CIVIL ENGINEERING DEPT.
NMAMIT-NITTE.
• Marsh cone
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.
Apparatus
• It’s consist 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.
PROCEDURE• 1L of 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.
TYPICAL MECHNICAL MIXER
MECHANICAL MIXER
The saturation dosage of super plasticizer can be defined as that point beyond which there is no significant decrease in the flow
time.
Variable parameters
• W/c ratio• Temperature(5-45 ‘C)• Admixtures (super plasticizer, retarder, accelerator, Air-
entraining admixtures, new generation super plasticizer.)
Figure 2 shows plots 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.
EFFECT OF TEMPERATURE ON THE FLUIDITY OF SUPER PLASTICIZED
CEMENT PASTE
Polycarboxylate Derivatives (PCE based) Sulfonated naphthalene-formaldehyde condensates (SNF)
Significance
• The saturation 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.
ADMIXTURES
• SUPER PLASTICIZER• RETARDER• ACCELERATOR• AIR-ENTRAINING ADMIXTURES• For the above all admixtures marsh cone test
can be adopted.
THANK YOU.