CMT - Lab. Rep. Determintion of setting time of Portland Cement PDF

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I. Title: LABORATORY WORK NO. 10: DETERMINATION OF SETTING TIME OF PORTLAND CEMENT II. Scope of the Test: The initial set is a stage in the process of hardening after which any cracks that may appear will not reunite. The concrete is said to be finally set when it has attained sufficient strength an...

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I. Title: LABORATORY WORK NO. 10: DETERMINATION OF SETTING TIME OF PORTLAND CEMENT II. Scope of the Test: The initial set is a stage in the process of hardening after which any cracks that may appear will not reunite. The concrete is said to be finally set when it has attained sufficient strength and hardness. III. Materials:  Sample of Portland cement IV. Apparatus and Method of Testing: A. Apparatus 1. Trowel – a small hand tool used for digging, applying, smoothing or moving small amounts of particulated material 2. Balance – used in determining the weight of materials 3. Saptula – a long flat metal with handle used to mix the materials 4. Pan – used in containing the materials during mixing and weighing 5. Graduated Cylinder - used for measuring volumes (amounts) of liquids 6. Vicat Apparatus - used to find out the consistency, initial setting time and final setting time of the cement 7. Rubber Mold – used to give the cement paste structure for testing B. Method of Testing 1. Test for fineness of cement. 2. Weight about 300 grams of cement accurately and make a paste with 0.85 times the water required to make a paste of normal consistency. 3. The paste is then placed in the rubber mold. 4. The small end of the rod is brought in contact with the surface of the paste and quickly released. 5. The penetration of the needle can be read on the goals. The initial set is said to have occured when the needle ceases to penetrate a point 5mm above the bottom of the mold. 6. The time taken for the instant of adding water to the cement up to the moment when the needle ceases to penetrate a point of 5mm above the mold is known as the initial setting time of the cement. For ordinary portland cement, the initial setting time should not be less than 30 minutes. V. Data and Result of the Test: a. Weight of the cement: 650 gms b. Volume of water: 215 mL c. Water-cement ratio: 1:.33 d. Initial setting time: 80 minutes e. Final setting time: 10 hrs

VI.

Trials

Time (min)

1 2 3 4 5 6 7 8 9 10 11 12

0 10 20 30 40 50 60 70 80 90 100 110

Depth of Penetration (mm) 44 44 44 44 44 44 44 41 39 (initial set) 38 37 31

Discussion: In the duration of the activity, the students observed the cement paste as it was subjected to the setting time test using the Vicat apparatus. Same paste used in the consistency test was utilized in this activity. Cement paste was made up of 650gm ordinary portland cement and 215mL clean water, and it has a consistency of 8mm falling under the dry consistency range. Right after consistency test, the cement paste was subjected to setting time test using the needly of the vicat apparatus and it had a depth of penetration of 44mm at 0 mins. Every after 10 minutes, the cement paste was penetrated by the needle. The test yielded 44mm depth of penetration from 0 mins to 60 mins. For the first 60 minutes, there was no change in the depth of penetration. At 70 minutes, a penetration of 41 mm was observed, it was the first change in the depth of penetration. Initial set occured at 80 mins, where the depth of penetration was 39 mm (5mm difference from the first trial). Initial set is where the cracks in the cement paste becomes permanent.The succeeding trials yielded 38mm, 37mm and 31mm. The last trial yielded a 31 mm depth of penetration at 110 minutes. Unfortunately, final setting was not observed due to lack of time but researches show that ordinary portland cement’s final set is after 5 hours. The final set is the stage wherein the cement has hardened sufficiently and has attained the shape of the mold which it was cast.

1. Semi-logarithmic scale of time(x) and depth of penetration(y). Time required for a 25mm depth of penetration.

DEPTH OF PENETRATION

SEMI-LOG PLOT 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 10

f(x) = − 0.25 x + 50.74

Linear ()

100

TIME

2. Explain:

1000

a. Difference between hydraulic and non-hydraulic cement - The main difference between hydraulic and non-hydraulic cement is that hydraulic cement has the ability to set and harden underwater while non-hydraulic cannot set nor harden under water. The former can harden instantly and sets with hydration reaction. The latter, on the other hand, needs dry condition for it to set and harden, takes longer time to dry and gain strength, and hardens by carbonation. b. Dry process of manufacturing portland cement - In dry process, raw materials for cement manufacturing are dried and reduced to a fine powder in a grinding mill. The dry powder/ raw meal is then pumped into a blending silo and is blended by the passing of compressed air for a uniform and intimate mixture. The mixture is stored in a storage tank then fed to a rotary kiln to from clinkers. Clinkers are then ground in a ball mill where 2-3% of gypsum is added. It is then fed to cement silos then packed in a desired pack in a packing plant. 3. Eight types of portland cement and their uses. a. Type I (Normal) – used in general construction that does not require any special properties of other types b. Type IA (Normal, air entraining) – used in general construction and adapts to freeze-thaw cycle c. Type II (Moderate sulfate resistance) – ideal for heavy structures like abutments, piers, and retaining walls. d. Type IIA (Moderate sulfate resistance, air entraining) – used in heavy structures and adapts to freeze-thaw cycles e. Type III (High early strength) – used in constructions that is to be operational immediately, and where formwork needs to be removed and reused f. Type IIA (High early strength, air entraining) – used in constructions that is to be operational immediately, and where formwork needs to be removed and reused; and adapts to freeze-thaw cycle g. Type IV (Low heat of hydration) – suited for the construction of massive structures with a low surface-to-volume ratio, like gravity dams, where a large heat of hydration may result in dangerous cracks h. Type V (High sulfate resistance) – used in canal linings, retaining walls, and culverts which is prone to sulfate attacks 4. Significant characteristics of portland cement. - Porland cement is a hydraulic cement meaning it can harden underwater. It was named as such due to its resemblance to Portland stone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. It is caustic – can cause chemical burns. It has several types. 5. Gilmore apparatus

Used to determine the setting time of cement. The apparatus consists of two horizontal arms which carry two weighted steel needles precisely machined to meet5 the requirement. The initial needle 2.12 mm dia., weighs 113 g and the final needle 1.06 mm dia., weighs 453,6 g. VII.

Review of Related Literature: A. Title: Effects of Palm Oil Fuel Ash (POFA) Towards Consistency and Setting Time Properties of Concrete B. Author/s: Imran, N.F. , Hasri, M.N., Khairul Fitry, N.A., Hasan, D. & Ramli, M.Z.

C. Literature Review: The article studied the effects of palm oil fuel ash (POFA) on concrete’s consistency and setting time for it to be utilized in the constrcution of rigid pavements in Malaysia. Pozzolans are siliceous or siliceous and aluminous material which have no cementetious value but are incremental to the workability, strength and durability of concrete. Their particle size/ fineness greatly influences the properties of mortar or concrete because finer particle size improves packing and pozzolanic activity which leads to higher durability. Palm oil fuel ash (POFA), whose disposal is an environmental problem in Malaysia, is a pozzolanic material that improves concrete’s compressive strength. The finer it is, either by burning or grinding, the more compressive strength it will add to the concrete. POFA samples were obtained from a palm oil factory and were prepared by oven-drying fro 24 hours then sieving at 212 micrometer and liquifying at 1kg:200mL water. It was then subjected to consistency test and setting time test in accordance to BS EN 196-03:2005 and ASTM-C 150-09, respectively. The consistency test yielded same penetration for all sample regardless of POFA percentage and water percentage. Powder technique showed that higher POFA percentage means higher water percentage for standard consistency to be achieved. 5% POFA has the highest water % for this method. Liquidation technique also yielded same results having 5% POFA as the one with most water %. Journal states that the shape and fineness of pozzolan are crucial in achieving low water amount. The setting time test using powder technique showed that higher percentage of POFA means longer setting time. 5% POFA has the longest initial and final setting time. The liquidation technique yielded same results but with an increase in the setting time of POFA added mixtures. VIII. Appendices: Appendix 1: Reference/s - https://specialties.bayt.com/en/specialties/q/14173/what-is-thedifference-between-hydraulic-and-non-hydrauliccement/#targetText=Non%2Dhydraulic%20cement%20is %20cement,oxychloride%2C%20which%20has%20liquid %20properties. - https://homequicks.com/types-of-portland-cement-their-applications Appendix 2: Journal Appendix 3: Printed ASTM/AASHTO Manual Appendix 4: Photographs...