Cement Fineness Test (ASTM C 184 - 94)

CI V L 111 Cons onstruc truction tion M ater terials L AB II : CEMENT CEMENT TEST TEST  Tes  Test 1. Ce Cem ment fine fineness test (ASTM (ASTM C 18 184 - 94) Procedures - Place 50 g sample sample of ceme cement on a cle clean and dry dr y #10 #100 0 (hole (hole si size of  0.15 mm) sieve, with the pan attached to it. While holding the sieve and the uncove uncoverred pan in in both hands, sie sieve with with a gentle ntl e wr wriist motion until most of the fine materials have passed through and the residue looks fairly clean. - Pl P lace the cove coverr on the si sieve and re remove move the pan. Now holdi holding ng them fir mly in in one hand, gently ntly tap the si side of the the sieve. The T he dust adher adhering to the sieve wil will thus be di dislodged and the underside of the sieve may now be swept clean. - Empty the pan and thoroughly wipe it out with cloth or a napkin. Replace place the si sieve in the pan and car carefull ully re r emove move the cove coverr . Re R eturn tur n any coarser material in the cover, caught during tapping of the sieve. - Continue the sieving as described earlier, without the cover, depending on the condition of cement. - Continuously rotate the sieve along with gentle wrist motion, taking care not to spill any cement. Continue this for about 9 minute minutes. Re Replace place the cove coverr and cle clean, foll following owing the sam same proce procedure dur e as desc descrribed bed earl earliier. I f the cement is is in prope pr oper condit conditiion, ther there shoul should d now be no appre appreciable ciable dust re remai maining ning in the the residue or or adher adher ing to the sieve and the pan. - Conduct 1-minute test as follows: Hold the sieve in one hand, with the pan and the cover attached, in slightly inclined position and move it backward and forward in the plane of inclination. At the same time gently ntl y stri strike the side about about 150 time ti mes per minute minute aga agaiinst the palm of  the other hand on the upstroke. Perform the sieving over a sheet of  white white pape paperr. Re R eturn tur n any mate materrial escaping escaping from fr om the si sieve or pan and collecting on the paper. amount unt of ceme cement re r emai mained. ned. - Weigh the amo W= Rt = Calculation F =100 - (Rt/W) 100 = Where here F = fineness of ceme cement expre expressed as the per centage centage passing #100 sieve, R t = weight re remai maining ning in #10 #100 0 si sieve, ve, and W =total weight of the sample in grams. Discussion Question: How does the finene fi neness of of ceme cement aff affect the the stre str ength gain and heat heat of  hydration hydration in i n concr concrete? te?

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 Test 2.

Normal consistency test (ASTM 187 - 86 Re approved 1991) Definition of terms - Normal consistency: A standard measure of plasticity of a cement paste. A paste has normal consistency when a Vicat plunger penetrates 10 ±1 mm in 30 sec. Procedures - Secure 500 g. of cement - Mix cement with measured quantity of clean water - M ould cement paste into shape of a ball. With gloved hands, toss ball six times through a free path of about six inches from one hand to another. - Press ball into larger end of Vicat ring and completely fill ring with paste. - Remove excessive paste without compressing samples and locate ring under plunger of Vicat apparatus. - Place plunger in contact with top of paste and lock. Set indicator on the scale to zero. - Release plunger and record settlement of plunger in mm after 30 seconds. - Repeat process with trial paste with varying percentages of  water until normal consistency is observed. Record the initial time of the test: (when you start to pour water into cement)  T =_____hour______min.______seconds Record the weight of water added to 500g of cement, when the plunger penetrates 10mm (9mm to 11mm) in 30 seconds. W =________ g of water.

Discussion Question: With finer cement particle size, would more or less water be required to achieve the normal consistency? Briefly explain.

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 Test 3.

Set time test (ASTM C 191 - 92) Definition of terms: - Time of initial set: The time at which the concrete can no longer be properly mixed, finished or compacted. (Represented by a Vicat needle penetration of 25 mm or less). - Time of final set: The time required for the cement to harden to a point where it can sustain some load. (Represented by no penetration of Vicat needle.) Procedures - Mix 500 g of cement with the percentage of water required for normal consistency as described above. (The specimen used for the normal consistency test can be used.) - After moulding cement paste into the test ring, place specimen in moist room for 30 minutes. - Place specimen ring under Vicat apparatus and lock needle on surface of paste. Set indicator scale to zero. - Release weighted needles and record the penetration in mm after 30 seconds. - Repeat process every fifteen minutes until initial set is achieved. - Repeat processes every hour until final set is achieved. Calculation - Calculate the time to the nearest minute required for the paste of normal consistency to achieve initial and final sets.

Record the time of initial set: (Represented by a Vicat needle penetration of 25 mm or less.)  T =_________hour ___________min.____________seconds Record the time of final set: (Represented by no penetration of Vicat needle.)  T =_________hour ___________min.____________seconds Discussion Questions: (1) Does the initial setting time satisfy the requirements of the British Standards? (2) Discuss briefly the significance of determining the initial and final setting times.

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 Test 4

Effect of superplasticizer (water reducer): a demonstration

 The water reducer is used as an aid to increase workability of fresh concrete without increasing water content or maintaining the same workability with a reduced amount of water (so the strength can be increased). The water reducer is available in both liquid and solid form. In this simple test, 100 grams of cement is weighed and 38 ml of water is measured. They are strongly mixed in a beaker for 3 minutes. The paste workability should be observed.  Then 1 g of K FDN solid powder is added into the paste. After mixing for another 3 minutes, the improved workability can be observed.  Test 5

pH value of cement slurry

Cement and concrete provides an alkaline environment to prevent the corrosion of reinforced steel. The high alkalinity is due to the presence of hydroxide in the hydration products.  To find the pH of cement slurry, 100 grams of cement and 100 ml of water are mixed in a beaker for about 5 minutes. After about 10 minutes, the surface liquid of  the slurry is tested with the pH indicator paper. What is the measured pH value ? NOTE: Tests 4 and 5 are for demonstration and there is NO need to include them in your laboratory report.

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