Jan 24, 2020

Session 4 : Compaction Work (Free Online Quantity Survey and Estimation Course)


1. Name of Work & Description         

Compaction work is required after the backfilling work of the foundation of the building or any structure from a hard surface. Compaction should be done in only layers up to 300mm to 500mm for road, building, bridge foundation, etc.
Compaction of backfilling work is the most important factor in the construction field. A lot of structures life depends on the compaction of backfilling material.

Types of using of Material Compaction Work.
1 Soft Soil
2 Murum (Same Gravels)
3 Murum (Brown Stone Color uniform size)
4 Murum (60-100mm size)
5 Boulders: Good Compaction is Not Possible for Boulders
6 Debris: Good Compaction is Not Possible for Debris, but if gravels size will be small, then it will be possible.

2. IS Code No.

IS Code for Methods of test for Soils: IS 2720: Determination of water content- dry density relation using light compaction.

IS Code for Methods of test for Soils: IS 10074: Compaction mold assembly for light and heavy compaction test for soils

3. The Drawing Needs to Read.

Compaction work is part of Backfilling work which required the same drawing
Following drawing need to read before Compaction work.
1 Building Foundation and Section Plan
2 Bridge Embankment Foundation and Section Plan
3 Plinth Section
4 Reduced Level Plan of Existing Ground
5 Plot Layout Drawing
6 Road Level Top and Bottom
7. Road The section as per Ground Level
8. Foundation Section Drawing

4. Location of Work

Compaction work can be done with the following Locations.
1 Building Foundation
2 Podium Foundation
3 Basement
4 Under Ground Water Tanks
5 Bridge Foundation
6 Culvert
7 Dam
8 Trench
9 Road
10 Bridge Embankment
11 KT Weir Embankment

5. Standard Procedure of Work (Step by Step)

Work Procedure before Start the Compaction

1 Read Plot Layout Drawing Carefully.
2 Calculate Approximate measurements to get the idea of required backfill material.
3 If compaction is proposed then 1.5 times the quantity of material is required to backfill.
3 Read Foundation drawing plan, where Footing and Raft of the building is outside then building line.
4 Calculate Outer to outer distance from foundation drawing of building or bridge structure.
5 Do site visit of Backfill material quarry. Please keep quarry distance nearest form your site.
6 Finalize material as per your requirement.
7 Finalize the rate as per your budgeted amount for backfilling work.
8 Arrange the material for testing of the Proctor density Test.

Work Procedure during the Compaction

1 Remove all the Material from Pit, or Backfilling Area.

2 Fill loose material with help of machine up to 300mm height.
3 Do not backfill murum more than 300mm.
4 Do not allow boulders in Backfill murum.
5 Do not allow any vegetation/twigs
6 Do not allow keep the boulders near RCC structure, it can be damaged RCC member.
7 Compaction must be done by first filling the excavated soils in layers of 300–500mm and tamping it with a vibrator. Till the desired level. The soil is moistened up to the optimum moisture content to establish optimum compaction and best results.

8 Barricade the area compaction area when machinery is working.

9 Check and Note down backfilled area levels with help of an Auto level.

10 Proctor Density Tests should be done at each layer.

6. Checkpoints

1 Check Machine Capacity, as well as which types of machinery, are required to compaction work.
2 Instruct to machine operator regarding the depth of Backfilling Material as well as the thickness of each layer.
3 Instruct to Operator to compact each layer properly.
4 Compact each layer of the earth not exceeding 200mm.
5 Earth/soil should be free of vegetation/twigs if any.
6 Earth/soil should be free of boulders if any.
7 Rolling should be done with a 5-ton mechanical roller after sprinkling enough water and core cutter samples taken for every 150sq.m
8 Proceed to the next layer after achieving a minimum of 95 % of MDD (maximum dry density).
9 Keep all workers Safe distance from Machine.
10 Compaction must be done by first filling the excavated soils in layers of 30–50 mm and tamping it with a vibrator. Till the desired level. The soil is moistened up to the optimum moisture content to establish optimum compaction and best results.
11 After completion of compaction arrange the architect visit to inspect the level as per Sections.
Check the Plinth Level and desired level before complete the backfilling, also keep down the level of backfilling area for Soling, PCC & Flooring, or for Road work keep the level down for WBM, Tack Coat, Seal Coat Etc.
12 Please check Depth of Soling, PCC, Footing/Raft, and Plinth Beam before completing the excavation.
For Example:    If Plinth Level is Given 1.0m Above GL.
Then Calculate Minimum Backfilling Depth
                        Soling for Footing: 0.23m
                        PCC for Footing: 0.15m
                        Tiling Work: 0.050m
                        Then Top Level of Compacted Backfill Area is 0.57m below from Plinth Height.

7. Equipment and Machinery

There are two types of Compaction is done

Manual Compaction

Manual Compaction can be done with 250-1000kg Compactor can be used for Compaction,  It will be too much costly and time consumable. This process is using under the building, a small area of work, etc.

Mechanical Compaction.

With the help of advance technology excavation is made too much easy and cost-effective as well as time-saving.
Following The machine is using for excavation
1 Backhoe Loader (JCB)
2 Mini Excavator (Mini poclain, Bob-Cat)
3 Mini Compactor
4 Plate Compactor
5 Road Roller
6 Grader
7 Vibro Roller
8 Water Tanker
9 Dozer
10 Rammer

8. Measurement and Quantity Survey

For the Calculation of the backfilling area and quantity of backfilled material, we need the following points.
1 Excavated ground level reading: Average level of each interval
2 Compacted Ground Level Reading: Average level of each interval.
3 Actual compacted Area: Prepare geometrical shapes as per level interval as we can find an exact compacted area as well as the depth of the compacted backfilling area.

Depth of Compacted Backfilling = RL of excavated GL – RL of compacted backfilled GL

Quantity of Compacted Backfilled Area = Actual backfilled Area X Depth of compaction Backfilling  
Compaction Work Unit is Square Meter or Square Feet.

9. Checklist

Proctor Density Test Details

Test Objective: To determine the required amount of water to be used when compacting the soil in the field and the resulting degree of denseness; this can be expected from compaction at optimum moisture content.
1 Cylindrical metal mold shall be either of 100mm diameter and 1000cm3 volume or 150mm diameter and 2250cm3 volume and shall conform to IS 10074 – 1982. 
2 Balance of capacity 500grams and sensitivity 0.01gram.
3 Balance of capacity 15Kg and sensitivity one gram.
4 Thermostatically controlled oven with capacity up to 250degree celsius. 
5 Airtight containers.
6 Steel straight edge about 30cm in length and having one beveled edge.
7  4.75mm, 19mm, and 37.5mm IS sieves confirming to IS 460 (Part 1).
8  Mixing tools such as tray or pan, spoon, trowel and spatula or suitable mechanical
9 device for thoroughly mixing the sample of soil with additions of water. 
10 Heavy compaction rammer confirming to IS: 9189 -1979.

1 Take a representative sample of air-dried soil of about 5 kg (soil not susceptible to crushing during compaction) or 3 kg from 15 kg sample (soil susceptible to crushing during compaction) passing through 19mm IS sieve and mix thoroughly with a suitable amount of water depending on the type of soil, generally 4 to 6 percent for sandy and gravelly soils and plastic limit minus 8% to 10% for cohesive soils. 
2 For soils susceptible to crushing during compaction take different samples for every determination and for soils not susceptible to crushing during compaction use the same sample for all the determinations. 
3 Weigh the 1000cc capacity mold with the base plate attached and without extension to the nearest gram (m1).  4 Place the mould on a solid base such as a concrete floor or plinth and compact the moist soil into the mold, with the extension attached in 5 layers of approximately equal mass, each layer being given 25 blows with the 4.90kg hammer dropped from a height of 450mm above the soil. 
5 Distribute the blows uniformly on each layer.
6 The amount of soil used shall be sufficient to fill the mold leaving not more than about 6mm to be struck off when the extension is removed.

Compaction of soil into the mold 

7 Remove the extension and carefully level the compacted soil to the top of mould by means of the straight edge. 
8 Weigh the mould and the soil to the nearest gram (m2). Remove the compacted soil from the mold and place on the mixing tray. 
9 Collect a representative sample from the soil in the tray and keep in the oven for· 24 hours maintained at a temperature of 1050 to 1100 C to determine the moisture content (W).

Compacting soil containing coarse material up to 37.50 mm size 
10 Take representative sample of material passing through 37.50 mm IS sieve.
11 Compact the material in 2250 cm3 volume of mold in five layers each layer being given 55 blows with 4.90 kg rammer dropped from a height of 450mm above the soil. 
12 The remaining procedure is the same as described above for 1000cc mold.
13 In all the above cases make at least five determinations and the range of moisture content shall be such that the optimum moisture content at which the maximum dry density occurs is within that range.
Calculate the bulk density gw in g / cm3g  of each compacted specimen from the equation,
 gw = (m2 – m1) / Vm
m1 = Weight of the mould with base plate.
m2 = Weight of the mould with compacted soil.
Vm = Volume of mold in cm3.
Calculate the dry density gd in g/cm3  from the equation,
gd =gw / (1+W/100)
 g w = Bulk density
 W = % of moisture content

1 Plot the values obtained for each determination on a graph representing moisture content on the x-axis and dry density on the y-axis. 
2 Draw a smooth curve through the resulting points and determine the position of the maximum in the curve. 
3 Report the dry density corresponding to the maximum point to the nearest 0.01.
4 Report the percentage corresponding to the maximum dry density i.e. optimum· moisture content to the nearest 0.2 %for values below 5% and to the nearest 0.5% for values from 5 to 10% and to the nearest whole number for values exceeding 10 %.

With clays of high plasticity or where hand mixing is employed, it may be difficult· to distribute the moisture uniformly throughout the air-dried soil by mixing alone, So it may be necessary to preserve the mixed sample in a sealed container for a minimum period of about 16 hours before conducting the test.

10. On-site Experience

Readers Experience: In our industrial project in during the execution our work tender is only RCC and Structural work, and Excavation and backfilling in Client scope, so after completion of the footing of the industrial building they backfilled the loose material and compaction is not done properly due to less time. But from this plot old nalla is passed, and there is muddy soil up to 6m from ground level, but due to not proper compaction and not proper execution done by earthwork contractor our building area trimix floor is going down up to 600mm after completing all the work. So please do proper compaction otherwise it may be more costly than your budget.
Mr. Riyaz (Engineer)

CBEC India

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