CE 121 Bulk Density, Void Content and Surface Moisture of Aggregates

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CE 121 Unit Weight, Void Content and Surface Moisture Content of Aggregates Lab Activity No. 3 Formal Report Lean Michael P. Tapel 2004-04165 BS Civil Engineering I. Objectives The main goals for this activity are to: a. To determine the bulk density (“unit weight”) in loose or compacted condition. b. To compute the void content in fine and coarse aggregates c. To determine the percentage of evaporable moisture in a sample aggregate by drying both surface moistu
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  CE 121Unit Weight, Void Content and Surface Moisture Content of AggregatesLab Activity No. 3 Formal ReportLean Michael P. Tapel2004-04165BS Civil Engineering  I.   ObjectivesThe main goals for this activity are to:a.   To determine the bulk density (“unit weight”) in loose or compacted condition.  b.   To compute the void content in fine and coarse aggregatesc.   To determine the percentage of evaporable moisture in a sample aggregate by dryingboth surface moisture and moisture in the pores of the aggregate.II.   Experimental Procedurea.   Equipment and Materials1.   Sieves2.   Tamping Rod3.   Measure/ Mold4.   Vessels5.   Oven6.   Shovelb.   Methodology1.   Data Sampling. Sampling should be done in accordance with Practice D75.These were thoroughly mixed and reduced to an amount suitable for testingusing the applicable procedures described in Practice C702.2.   Washing. The samples gathered were washed with flowing water inside thecontainer in order to remove the impurities in it. Then, the water would besifted out from the container where it was washed3.   Oven-Drying. Place the sample in a container and it would be dried to aconstant mass at a temperature of 110  5 O C. The sample would be dried for aduration of 24  4 hours then let it cool down until desired temperature isachieved. Determination of Bulk Density and Void Content of Coarse and FineAggregates 1.   Rod Tamping. Fill the Mold with a third of the volume and level thesurface with fingers. Using the rod, tamp the surface with 25 strokesuniformly spread all over. Fill the measure two-thirds full and again levelthe rod as above. Finally, fill the measure to overflowing and rod againin the manner previously mentioned. Level the surface of the aggregatewith the fingers or a straightedge in such a way that any slightprojections of the larger pieces of the coarse aggregate approximatelybalance the larger voids in the surface below the top of the measure.  Be cautious in preventing the rod to strike the bottom of the measureforcibly. In tamping the second and third layers, use vigorous effort, butnot more force than to cause the tamping rod to penetrate to theprevious tamping layer. Determination of Surface Moisture Content of Aggregates 2.   Measure of oven dried Aggregate. Get the weight of the oven-driedaggregate.c.   Equations Utilized UNIT WEIGHT (OD condition) V T G M  / )(    where:  M  = bulk density of aggregate G = mass of the oven dried-aggregate plus the measure T  = mass of the measure V  = volume of the measure VOID CONTENT       W S M W SVoid   100%   where:  M  = bulk density of the aggregate S = bulk specific gravity (dry basis) as determined in accordance W  = density of water, 998 kg/m 3   SURFACE MOISTURE CONTENT   D DW  p  100    A pSMC     where:  A = Absorption (get values calculated from Lab Experiment 2) W  = mass of srcinal sample  D = mass of dried sample  p = Total Evaporable Moisture Content SMC  = Surface Moisture Content   III.   Results and DataData gathered were plotted on the table below. Results were computed simultaneously forboth fine and course aggregate. FINE COARSEAggregate (ORIGINAL),kg 1.68 6 Aggregate (DRY),kg 0.48414 4.299 Aggregate(DRY&Untamped) + Mold,kg 6.344 6.155 Aggregate(DRY &Tamped) + Mold ,kg 6.617 6.809 Absorption 3.3 9.2 Bulk Specific Gravity(DRY) 8.59 3.44 Mold,kg 2.211 Volume m^3 0.002678 FINE COARSETotal Evaporable MoistureContent 247.0071 39.56734 Surface Moisture Content 243.7071 30.36734 Bulk Density (Dry Basis) 3345.046 3192.079 Void Content 60.98079 7.021049Unit Weight/Bulk Density, Void Content and Surface moisture contents were computed forboth fine and coarse aggregates.IV.   DiscussionThe experiment has provided data necessary for solving the Total Evaporable MoistureContent which is a requisite for solving Surface Moisture Content. Then a similar set of datais needed to solve the Bulk Density (dry basis) or also known as Unit Weight for both Fineand Coarse Aggregates. Void Content was then computed through tamping of the aggregateby a rod.With values guided by American Society for Testing and Materials (ASTM), a certain rangecould be considered useful in cement applications. Unit Weight range is between 1200-1760kg/m 3 . Void content also has normal ranges of 30-45% for coarse aggregates and 40-50% forfine aggregates. Absorption is a value that helps determine proper proportioning for
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