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UNIVERSITY OF THE EASTCOLLEGE OF ENGINEERINGCIVIL ENGINEERING DEPARTMENTCALOOCAN

CONSTRUCTION MATERIALS AND TESTING

EXPERIMENT No. 1SPECIFIC GRAVITY AND ABSORPTION OF COARSE AGGREGATE

PurposeTo determine the specific gravity and absorption of coarse aggregate. The specific gravity may be expressed as bulk specific gravity, bulk specific gravity SSD (saturated-surface dry), or apparent specific gravity.

Significance and UseBulk specific gravity is generally used for the calculation of the volume occupied by the aggregate in various mixtures containing aggregates, including portland cement concrete, bituminous concrete and other mixtures that are proportioned or analysed on an absolute volume basis. Bulk specific gravity SSD is used if the aggregate is wet. Absorption values are used to calculate the change in the weight of aggregate due to water absorbed in the pore spaces within the constituent particles, compared with the dry condition.

Apparatus Balance accurate to 0.05% of the sample weight of 0.5 g, whichever is greater Wire basket 3.35 mm (No. 6) or finer mesh Water tank 75 mm (No. 4) sieve

Test Specimens Thoroughly mix the aggregate sample and reduce it to the approximate quantity needed. Reject all materials passing 4.74 mm sieve by dry sieving and thoroughly washing to remove dust or other coatings from the surface.

Test Procedure1. Immerse the aggregate in water at room temperature for a period of 24 4 hours.2. Remove the latest test specimen from water and roll in a large absorbent cloth until all visible films of water are removed. Wipe the larger particles individually.3. Weigh the test sample in saturated surface-dry condition, and record it as B. Record this weight and all subsequent weights to the nearest 0.5 g or 0.05% of the sample weight, whichever is greater.4. Place the specimen in the wire basket and determine its weight while it is submerged in water at a temperature of 23 1.7 degree Celsius, and record it as C. Take care to remove all entrapped air before weighing it by shaking the container while it is immersed.5. Dry the test sample to a constant weight at a temperature of 110 5 degree Celsius, and weigh it and record this weight as A.

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Analysis and Results1. Bulk specific gravity = Where = mass of oven-dry sample in air, g.= mass of saturated surface-dry sample in air, g.C = mass of saturated sample in water, g.2. Bulk specific gravity (SSD) = 3. Apparent specific gravity = 4. Absorption, % =

Report1. Show step by step computation2. Observation3. Recommendation4. Conclusion

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INTRODUCTION

Specific gravity is a measure of a materials density (mass per unit volume) as compared to the density of water at 73.4F (23C). Therefore, by definition, water at a temperature of 73.4F (23C) has a specific gravity of 1.Absorption, which is also determined by the same test procedure, is a measure of the amount of water that an aggregate can absorb into its pore structure. Pores that absorb water are also referred to as water permeable voids.Specific Gravity UseAggregate specific gravity is used in a number of applications including Superpave mix design, deleterious particle indentification and separation, and material property change identification.Superpave Mix DesignSuperpave mix design is a volumetric process; it relies on mixing constituent materials on the basis of their volume. However, aggregate and asphalt binder volumes are diffucult to measure directly, therefore a materials weight is typically measured and then converted to a volume based on its specific gravity. Correct and accurate material specific gravity determinations are vital to proper mix design. An incorrect specific gravity value will result in incorrect calculated volumes and ultimately result in an incorrect mix design.Material Contamination Indicator and SeparatorSpecific gravity can also indicate possible material contamination. For instance, deleterious particles are often lighter than aggregate particles and therefore, a large amount of deleterious material in an Differences in specific gravity can also be used to separate deleterious, or bad, particles from aggregate particles using a heavy media liquid. Water absorption can also be an indicator of asphalt absorption.

Material Change IndicatorFinally, specific gravity differences can be used to indicate a possible material change. A change in aggregate mineral or physical properties can result in a change in specific gravity. For instance, if a quarry operation constantly monitors the specific gravity of its output aggregate, a change in specific gravity beyond that normally expected could indicate the quarrying has moved into a new rock formation with significantly different mineral or physical properties.Aggergate Absorption UseAggregate absorption is the increase in mass due to water in the pores of the material. Aggregate absorption is a useful quality because:High values can indicate non-durable aggregate. 103

Absorption can indicate the amount of asphalt binder the aggregate will absorb.It is generally desirable to avoid highly absorptive aggregate in HMA. This is because asphalt binder that is absorbed by the aggregate is not available to coat the aggregate particle surface and is therefore not available for bonding. Therefore, highly absorptive aggregates (often specified as over 5 percent absorption) require more asphalt binder to develop the same film thickness as less absorptive aggregates making the resulting HMA more expensive.Aggregate Specific Gravity Types

Several different types of specific gravity are commonly used depending upon how the volume of water permeable voids (or pores) within the aggregate are addressed. Apparent Specific Gravity, Gsa.The volume measurement only includes the volume of the aggregate particle; it does not include the volume of any water permeable voids. The mass measurement only includes the aggregate particle. Apparent specific gravity is intended to only measure the specific gravity of the solid volume, therefore it will be the highest of the aggregate specific gravities. It is formally defined as the ratio of the mass of a unit volume of the impermeable portion of aggregate (does not include the permeable pores in aggregate) to the mass of an equal volume of gas-free distilled water at the stated temperature.Bulk Specific Gravity (Bulk Dry Specific Gravity), Gsb.

The volume measurement includes the overall volume of the aggregate particle as well as the volume of the water permeable voids. The mass measurement only includes the aggregate particle. Since it includes the water permeable void volume, bulk specific gravity will be less than apparent specific gravity. It is formally defined as the ratio of the mass of a unit volume of aggregate, including the water permeable voids, at a stated temperature to the mass of an equal volume of gas-free distilled water at the stated temperature.

Bulk Saturated Surface Dry (SSD) Specific Gravity.

Volume measurement includes the overall volume of the aggregate particle as well as the volume of the water permeable voids. The mass measurement includes the aggregate particle as well as the water within the water permeable voids. It is formally defined as the ratio of the mass of a unit volume of aggregate, including the weight of water within the voids filled to the extent achieved by submerging in water for approximately 15 hours, to the mass of an equal volume of gas-free distilled water at the stated temperature.

Effective Specific Gravity, Gse.Volume measurement includes the volume of the aggregate particle plus the void 410

volume that becomes filled with water during the test soak period minus the volume of the voids that absorb asphalt. Effective specific gravity lies between apparent and bulk specific gravity. It is formally defined as the ratio of the mass in air of a unit volume of a permeable

material (excluding voids permeable to asphalt) at a stated temperature to the mass in air (of equal density) of an equal volume of gas-free distilled water at a stated temperature. Effective specific gravity is determined by a different procedure and is not covered in this section.

ANALYSIS AND RESULTS

AFTER SIEVE

WEIGHT OF PAN347.60

WEIGHT OF AGGREGATES WITH PAN19581.10

TOTAL WEIGHT OF AGGREGATES19233.50

A

BMASS OF SATURATED SURFACE-DRY SAMPLE IN AIR(grams)

WEIGHT OF PAN366.80



CMASS OF SATURATED SAMPLE IN WATER(grams)

WEIGHT OF PAN1298.10



BULK SPECIFIC GRAVITY

Bulk specific gravity===

BULK SPECIFIC GRAVITY (SSD)

Bulk specific gravity (SSD)===2.8135

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APPARENT SPECIFIC GRAVITY

Apparent specific gravity===

ABSORPTION, %

Absorption= ==

OBSERVATION

Aggregates have different shapes, sizes and weight. As we strained the aggregates insieve number 4, some aggregates were filtered and some of the waters it has from soaking it at 20 hours was infiltrated. There should be an equal force applied on shaking the sieve so it will be precisely filtered.

RECOMMENDATION

First, you need to wear your laboratory gloves.

Second, you need to have complete materials in doing your experiments, so you willbe able to measure it continuously and you can weigh it again for you to see its real weight.

Third, it is most recommended that you use one weight of the pan that you will be use in weighing the aggregates.

Fourth, you need to record your gathered data as youve done on measuring its weight.

CONCLUSION

We therefore conclude that the mass of the aggregates differ when it is in water where it is saturated, in air where it is saturated surface - dry and in air where it is over dry.

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DOCUMENTATION

MATERIALS

AGGREGATES(75mm) SIEVE NO. 4

PANUSED CLOTHES/RUGS

OVENWATER TANK7

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WEIGHING SCALEWIRE BASKET 3.35 mm(No. 6) OR FINER MESH

PROCEDURE

IMMERSE THE AGGREGATE IN WATER AT TEMPERATURE FOR A PERIOD OF 24 PLUS OR MINUS 4 HOURS. THEN,

FILTER THE AGGREGATES WEIGH THE PAN

RUB THE AGGREGATES THEN, WEIGH THE AGGREGATES W/ PAN SEPARATE IT

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WEIGH THE WIRE BASKET ON WATER

PUT THE AGGREGATES ON WIRE BASKET IN WATER TO HAVE ITS WEIGHT

NCE 414

SPECIFICE GRAVITY AND ABSORPTION OF COARSE AGGREGATE

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3 CET10

TRANSFER THE AGGREGATES PLACE IT IN AN OVEN IN A PAN

OVEN TEMPERATURE THEN GET ITS WEIGHT3 CETNCE 4141010

SPECIFICE GRAVITY AND ABSORPTION OF COARSE AGGREGATE

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