CONSTRUCTION MATERIALS LAB

BY MESFIN D.1

presented By Mesfin

Introduction*Construction materials are those materials used in a construction of any civil engineering structures.In this lab more emphasis will be given to concrete making materials since they are the most widely used materials of construction.Those materials used in making concrete includesCement SandAggregatewater

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These construction materials must satisfy the standard quality requirements recommended by codes, so that the structure to be built will be functional, safe and economical.Therefore to assure the quality of these materials , laboratory tests are made for each material.We will see each experiment individually and they includes the followingFineness of hydraulic cementConsistency of hydraulic cementSetting time of hydraulic cementSpecific gravity and absorption of fine aggregateSilt content test

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Experiment No1fineness of hydraulic cement Objective: to determine the fineness of hydraulic cement by means of No 100 (150mm) and No 200 (75mm) sieves.Theory :The fineness to which cement has ground during its production can have an effect on the behavior of cement during hydration. The rate of hydration increases with increasing cement fineness which leads to higher rate of strength gain and on the other hand larger cement particles will not hydrate completely and hence retards the strength gain.

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Apparatus sieve No100 or No 200Balance brush Pan

contd Exp. No1

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Measure the residual in the sieve (Rs).

Calculation

Where F= fineness of cement in % which passes the sieves Rs= residual from the sample retained on the sieve W= weight of the sample

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Experiment No2* .Objective: This method is carried out to determine the amount of water required to prepare a standard cement paste.Theory :Cement is a finely ground material of chemically combined materials such as silica, alumina, lime etc. Thus when cement is mixed with water, it sets and hardens in to a solid mass upon hydration which is used to bind two or more non adhesive materials.The normal consistency of hydraulic cement refers to the amount of water required to make a neat paste of satisfactory workability.

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contd Exp. No2

Apparatus

Calculation

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contd Exp. No2

Trial NoWt. of cementWt. of water% age of waterInitial reading (mm)final reading (mm)Penetration (mm)remark123

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Experiment No3*.Objective: The objective of this test is to determine the initial and final setting time of cement paste with normal consistency.Theory :Cement forms a solid and hard mass when mixed with water upon hydration. This is what we call setting of cement.The duration a cement paste requires to undergo setting is its setting time and depends on w/c ratio. The initial setting time is the duration of paste related to 25mm penetration of the vicat needle in to the paste in 30seconds. while the final setting time is that related to zero penetration

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contd Exp. No3

Apparatus

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contd Exp. No3

Calculation:Calculate the initial and final setting times of the cement from the following data.

Trial NoTime (min)Initial reading (mm)final reading (mm)Penetration (mm)remark123

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Experiment No 4*4. Silt content testObjective: The objective of this test is to determine the silt content (impurities) of sand.Theory :Sand is a product of natural and artificial disintegration of rocks and minerals. These sources however do not produce a pure sand i,.e they contain other materials such as dust, loam or clay that are finer than sand.These impurities decrease the strength of mortar or concrete

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contd Exp. No 4

Apparatus

250ml measuring cylinder Tray clear waterSmall size spoon

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Calculation

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Experiment No5* Specific gravity and absorption of fine aggregate Objective: The objective of this test is to determine the bulk specific gravity, apparent specific gravity and absorption of fine aggregates.Theory :generally specific gravity is defined as the ratio of the mass of a unit volume of material to the mass of the same volume of water. it depends on the moisture content of the aggregates.SSD specific gravity and absorption are based on aggregates after soaking 20-28 hours.Apparatus

Balance Pycnometer/flask hot plate

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Trial No123remark1Weight of oven dry agg. in air,g A2Weight of pycnometer filled with water g, B3Weight of fine agg., pycnometer and water g, C4Weight of saturated surface dry fine agg., g, S

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contd Exp. No5

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Experiment No6* Specific gravity and absorption of coarse aggregate Objective: The objective of this test is to determine the specific gravity and absorption of coarse aggregates.Theory :Similar to Ex. No 5.

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contd Exp. No6

Apparatus

Calculation

Balance sample container water tankSieve No 4 (4.75mm)

Trial No123remark1Weight of oven dry agg. in air,g A2Weight of SSD agg. In air g, B3Weight of saturated surface dry agg., g, C

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contd Exp. No6

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Experiment No7* Silt content testObjective: The objective of this test is to determine the silt content (impurities) of sand.Theory :Sand is a product of natural and artificial disintegration of rocks and minerals. These sources however do not produce a pure sand i,.e they contain other materials such as dust, loam or clay that are finer than sand.These impurities decrease the strength of mortar or concrete

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contd Exp. No7

Apparatus

Calculation

250ml measuring cylinder Tray water cane

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Experiment No 8* Sieve AnalysisObjective: The objective of this test is to determine the particle size distribution of coarse aggregates.Theory :Aggregates make up about 65-75% of the volume of concrete. Therefore the quality of concrete is much influenced by the properties of the aggregates. Aggregate size distribution (gradation) is one of these properties of aggregate that affects the strength of concrete.

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contd Exp. No8

Apparatus

Calculation

set of sieves sieve shaker BalanceAir dried aggregate

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contd Exp. No8

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Experiment No9* Slump testObjective:

Theory :A concrete mix, either produced at a ready mix plant or on site, must be made of the right amount of the constituents to make the concrete workable enough for easy compaction and placing of concrete.If the mix is too dry, then its compaction will be too difficult and if it is too wet, then the concrete is likely to be weak.Slump test is the simplest test for workability of concrete.In the slump test, the distance that a cone of concrete slumps down is measured when the cone is lifted from the concrete.

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contd Exp. No9

Apparatus

Calculation

mould cone tamping rod

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Degree of workabilitySlump (mm)Very low0-25Low25-50Medium50-100high100-175

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Experiment No10* compacting factor testObjective:

Theory :An alternative way of measuring the workability of concrete is the compacting factor method which is more accurate than the slump method specially for low workability below 25mm.

Apparatus

compacting factor apparatus balancetrowel

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contd Exp. No7

Calculation

Trial Novalueremark1Weight of cylinder ,g AA2Weight of cylinder + weight of partially compacted concrete g, BB3Weight of cylinder + weight of fully compacted concrete g, CC4Weight of partially compacted concrete g, W1B-A5Weight of fully compacted concrete g, W2C-A6Density of partially compacted concrete r1W1/V7Density of fully compacted concrete r2W2/V8Compacting factor = r1/r2W1/W2

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Degree of workabilityCompacting factorVery low0.78Low0.85Medium0.92high0.95

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Experiment No11* Compressive strength of concreteObjective:

Theory :The major goal of structures is carrying loads coming to them from DL, LL, EQ or wind loads. The concrete produced therefore, must not fail under the actions of such loads. This test involves taking of a sample of fresh concrete and putting in to special cube molds so that, when hard, the cubes can be tested to failure in a special machine in order to measure the compressive strength of concrete.

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contd Exp. No11

Apparatus

Calculation

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Experiment No12* Flexural strength of concreteObjective:

Theory :This test gives a way of estimating tensile strength of concrete.During pure bending, the member resisting the action is subjected to internal or stress (shear, tensile and compressive)For a member simply supported subjected to down ward force, fibers above neutral axis are subjected to compression and below neutral axis to tensile stresses.In this test, the concrete member is supported at its ends and loaded at its interior locations by gradually increasing load to failure.The failure load is recorded and used to find the tensile strength.

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contd Exp. No11

Calculation

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Objective:

Theory :The aggregate impact value gives a relative measure of the resistance of an aggregate to sudden shock or impact, which in some aggregates differs from its resistance to a slowly applied compressive load.The standard aggregate impact test shall be made on aggregates passing 14mm BS(12.5mm ASTM) test sieve and retained on a 10mm BS test sieve.The aggregate shall be surface dry.The specimen is filled in three layers each tamped by 25blows.

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The hammer which is 380mm from the sample is released to crush the aggregate for 15 times.Weigh the fractions passing and retained on 2.36mm BS test sieve.

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Objective:

Every thing is similar to aggregate impact value except the load is applied gradually.

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