Dry Density Calculation

Illustrative video for calculation of Field density by using sand replacement method.

In soil compaction test, if a test result exceeds 100%, should engineers accept the result ?

Soil compaction is the process of increasing the soil density by reducing the volume of air within the soil mass. Soil compaction depends mainly on the degree of compaction and the amount of water present for lubrication. Normally 2.5kg rammers and 4.5kg rammers are available for compaction in laboratories and the maximum dry densities produced by these rammers cover the range of dry density obtained by in-situ compaction plant. Regarding the second factor of water content, it affects the compaction in the following ways. In low water content, the soils are difficult to be compacted. When water content is increased gradually, water will lubricate the soils and this facilitates the compaction operation. However, at high water content, as an increasing proportion of soils is occupied by water, the dry density decreases with an increase in water content.
For soil compaction tests, the dry density obtained from compaction carried out in-situ by vibrating roller/vibrating plate is compared with the maximum dry density conducted in laboratories using 2.5kg rammer of compaction with similar soils. In essence, the in-situ compaction is compared with the compacting effort of using 2.5kg (or 4.5kg) rammer in laboratories. In case the compaction test results indicate values exceeding 100%, it only means that the in-situ compaction is more than that being carried out in laboratories which is treated as the basic criterion for satisfactory degree of soil compaction. Therefore, the soil results are acceptable in case compaction test results are over 100%. However, excessive compaction poses a risk of fracturing granular soils resulting in the reduction of soil strength parameters.

What is the importance of air void content in bituminous pavements?

The air void content of bituminous materials is an important control parameter for the quality of bitumen being laid and compacted. If the air void content is too high, it allows for intrusion of air and water. Moreover, it also increases the rate of hardening of binders which produce premature embrittlement of pavements. In addition, too high a void content will also lead to differential compaction subject to traffic loads and result in formation of ruts and grooves along the wheel track. However, a minimum amount of air void should be maintained to avoid instability during compaction process and to provide space for bitumen flow in long-term consolidation under traffic loads. A sufficient amount of air voids should be designed to make room for expansion of binder in summer and compaction by road traffic, otherwise bleeding and loss of stability may occur and the pavement will deform readily under severe loads.

Is it desirable to use concrete of very high strength, exceeding 60MPa? What are the potential problems associated with such high strength concrete?

To increase the strength of concrete, say from 40MPa to 80MPa, it definitely helps in improving the structural performance of the structure by producing a denser, more durable and higher load capacity concrete. The size of concrete members can be significantly reduced resulting in substantial cost savings. However, an increase of concrete strength is also accompanied by the occurrence of thermal cracking. With an increase in concrete strength, the cement content is increased and this leads to higher thermal strains. Consequently, additional reinforcement has to be introduced to control these additional cracks caused by the increase in concrete strength. Moreover, the ductility of concrete decreases with an increase in concrete strength. Attention should be paid during the design of high strength concrete to increase the ductility of concrete. In addition, fire resistance of high strength concrete is found to be less than normal strength concrete as suggested by Odd E. Gjorv (1994).

Though the tensile strength of high strength concrete is higher than that of normal concrete, the rate of increase of tensile strength is not proportional to the increase of compressive strength. For normal concrete, tensile strength is about one-tenth of compressive strength. However, for high strength concrete, it may only drop to 5% of compressive strength. Moreover, owing to a low aggregate content of high strength concrete, creep and shrinkage increases.

Density/Unit Wt. (kg/cu.m.) of some Engineering Materials

Material - powder, ore, solids, etc. kg/cu.m.


Asphalt, crushed 721
Bark, wood refuse 240
Basalt, broken 1954
Basalt, solid 3011
Bauxite, crushed 1281
Brick, common red 1922
Brick, fire clay 2403
Brick, silica 2050
Brick, chrome 2803
Brick, magnesia 2563
Cement - clinker 1290-1540
Cement, Portland 1506
Cement, mortar 2162
Cement, slurry 1442
Clay, dry excavated 1089
Clay, wet excavated 1826
Clay, dry lump 1073
Clay, fire 1362
Clay, wet lump 1602
Clay, compacted 1746
Concrete, Asphalt 2243
Concrete, Gravel 2403
Concrete, Limestone with Portland 2371
Dolomite, solid 2899
Dolomite, pulverized 737
Dolomite, lumpy 1522
Earth, loam, dry, excavated 1249
Earth, moist, excavated 1442
Earth, wet, excavated 1602
Earth, dense 2002
Earth, soft loose mud 1730
Earth, packed 1522
Earth, Fullers, raw 673
Glass - broken or cullet 1290-1940
Glass, window 2579
Gneiss, bed in place 2867
Gneiss, broken 1858
Granite, solid 2691
Granite, broken 1650
Graphite, flake 641
Gravel, loose, dry 1522
Gravel, with sand, natural 1922
Gravel, dry 1/4 to 2 inch 1682
Gravel, wet 1/4 to 2 inch 2002
Gypsum, solid 2787
Gypsum, broken 1290-1600
Gypsum, crushed 1602
Gypsum, pulverized 1121
Iron ore - crushed - see metals table 2100-2900
Iron oxide pigment 400
Iron Pyrites 2400
Iron sulphate - pickling tank - dry 1200
Iron sulphate - pickling tank - wet 1290
Lime, quick, lump 849
Lime, quick, fine 1201
Lime, stone, large 2691
Lime, stone, lump 1538
Lime, hydrated 481
Lime, wet or mortar 1540
Marble, solid 2563
Marble, broken 1570
Marl, wet, excavated 2243
Mica, solid 2883
Mica, broken 1602
Mica - flake 520
Mica - powder 986
Mortar, wet 2403
Mud, packed 1906
Mud, fluid 1730
Peat, dry 400
Peat, moist 801
Peat, wet 1121
Pyrite (fool's gold) 2400 - 5015
Quartz, solid 2643
Quartz, lump 1554
Quartz sand 1201
Rock - soft - excavated with shovel 1600-1780
Rosin 1073
Rubber, caoutchouc 945
Rubber, manufactured 1522
Rubber, ground scrap 481
Sand, wet 1922
Sand, wet, packed 2082
Sand, dry 1602
Sand, loose 1442
Sand, rammed 1682
Sand, water filled 1922
Sand with Gravel, dry 1650
Sand with Gravel, wet 2020
Sandstone, solid 2323
Sandstone, broken 1370-1450
Sawdust 210
Sewage, sludge 721
Shale, solid 2675
Shale, broken 1586
Slate, solid 2691
Slate, broken 1290-1450
Slate, pulverized 1362
Snow, freshly fallen 160
Snow, compacted 481
Stone, crushed 1602
Stone (common, generic) 2515
Tar 1153
Trap rock, solid 2883
Trap rock, broken 1746
Turf 400
Turpentine 865
Water, pure 1000
Water, sea (see liquids table) 1026
Wood chips - dry - see wood table 240- 520

Metal/Alloys


aluminium - melted 2560 - 2640
aluminium bronze (3-10% Al) 7700 - 8700
aluminium foil 2700 -2750
beryllium copper 8100 - 8250
brass - casting 8400 - 8700
brass - rolled and drawn 8430 - 8730
bronze - lead 7700 - 8700
bronze - phosphorous 8780 - 8920
bronze (8-14% Sn) 7400 - 8900
cast iron 6800 - 7800
copper 8930
gold 19320
iron 7850
lead 11340
light alloy based on Al 2560 - 2800
light alloy based on Mg 1760 - 1870
magnesium 1738
mercury 13593
nickel 8800
nickel silver 8400 - 8900
silver 10490
steel - rolled 7850
steel - stainless 7480 - 8000
tin 7280
titanium 4500
tungsten 19600
zinc 7135

Wood - seasoned & dry kg/cu.m

Apple 660 - 830
Ash, black 540
Ash, white 670
Bamboo 300 - 400
Oak 590 - 930
Pine ( Oregon ) 530
Pine ( Parana ) 560
Pine ( Canadian ) 350 - 560
Pine ( Red ) 370 - 660
Teak 630 - 720

Liquid Temp kg/cu.m

Crude oil, 48° API 60 F 790
Crude oil, 40° API 60 F 825
Crude oil, 35.6° API 60 F 847
Crude oil, 32.6° API 60 F 862
Crude oil, California 60 F 915
Crude oil, Mexican 60 F 973
Crude oil, Texas 60 F 873
Diesel fuel oil 20 to 60 15 C 820 - 950
Fuel oil 60 F 890.13
Kerosene 60 F 817.15
Petrol, natural 60 F 711.22
Petrol, Vehicle 60 F 737.22
Sea water 25 C 1025.18
Terpinene 25 C 847.38
Water, pure (more temperatures) 4 C 1000.00
Water, sea 77 F 1021.98

Some Land and Distance Measurement Units used in Nepal

In Nepal we use different units for measurement of land. In hilly regions we use Ropani-Ana-Paisa-Dam system while in Southern parts i.e. at Terai region we use Bhigha-Kattha-Dhur system.

The conversion between these units and also to the SI unit is essential as we come across this situation often.

The conversion factor for these units is as follows

Ropani-Ana-Paisa-Dam system

•1 Ropani =16Ana
•1 Ana =4 Paisa
•1Paisa =4 Dam
Bhigha-Kattha-Dhur system

•1 Bhigha= 20 Kattha
•1 Kattha= 20 Dhur
For inter conversion between Ropani and Bhigha

•1Bhigha=13 Ropani
Similarly in standard units we may use

•1 Ropani =74feet X 74 feet
•1 m=3.28 feet

Distace

The kos is an ancient unit of distance that has been in use for over three thousand years; evidence exists from Vedic times to the Mughal period, and even now elderly people in rural areas refer to distances from nearby areas in kos. A kos is about 2.25 miles.

It is variously spelled "Kos", "Kosh", "Krosh", and "Koss" when rendered in the Latin alphabet.

1 Angul (approximate width of a finger) = approx. 3/4 of present day inch;
4 Angul = Dharnugrah (bow grip) = 3 in;
8 Angul = 1 Dhanurmushti (fist with thumb raised) = 6 in;
12 Angul = 1 Vitastaa (span-distance of stretched out palm between the tips of a person's thumb and the little finger) = 9 in;
2 Vittaa (from the tip of the elbow to the tip of the middle finger) = 18 in;
4 (Haath) = 1 Dand or Dhanush (bow) = 6 ft;
2000 Dand (Dhanush) = 1 Kosh or Gorut = 4000 yards or 2 1/4 miles - nearly 3.66 km;
4 Kosh = 1 Yojan = 9 miles - nearly 15 km;

Construction Business

The modern industrialized world at present has made the construction industry to play a major role in the field of economy. It has become an important means for a country’s growth. Building construction is the process of adding structure or assembling of infra structure, for roads, buildings, airports, bridges or anything. The civil engineers are those who design these things. In our day to day life we come across a numerous things, which we would not have got into use, without the help of civil engineers. They sketch up the outlook of these roads or buildings and as per their designs; the roads are constructed. Civil Engineers are those who built a real city, from roads and bridges to tunnels, public buildings, and sewer systems.

The modern industrialized world at present has made the construction industry to play a major role in the field of economy. It has become an important means for a country’s growth. Building construction is the process of adding structure or assembling of infra structure, for roads, buildings, airports, bridges or anything. The civil engineers are those who design these things. In our day to day life we come across a numerous things, which we would not have got into use, without the help of civil engineers. They sketch up the outlook of these roads or buildings and as per their designs; the roads are constructed. Civil Engineers are those who built a real city, from roads and bridges to tunnels, public buildings, and sewer systems.

There are several factors that a civil engineer must consider, before getting into construction. They must be aware of the cost and also make sure that the structure remains consistent during bad weather. There are different forms in which a civil engineer could work. They may work in design, construction, research, and teaching. Most of them prefer to handle people and projects. Civil engineering specialties include structural, construction, environment, and transportation.

Generally, a construction process consists of three phases: preconstruction planning, implementation, and infrastructure maintenance. Under the preconstruction phase, surveying a land or property is done initially. Then plans are reviewed and funding is made. After that the schedule is decided to start the construction. Construction begins in the implementation phase. Most of the civil engineers spend a considerable time on-site reviewing the progress of construction. They also co-ordinate the employees, so that the construction work could be finished at the earliest. Finally the infrastructure maintenance phase involves evaluations and stress tests. This takes place after the construction work gets over. All the final adjustments are made and with the paper works being documented, the process gets finished.

The civil engineers usually prefer to work in manufacturing and business areas. A Civil engineer need to be creative, curious, analytical, and detail-oriented. Most of the male students are crazy about such jobs, where they could design things and construct them accordingly. Initially, to qualify for a job as a civil engineer, you need to hold a degree in civil engineering. At the beginning, some engineers work under an experienced engineer to learn things in a perfect and effective way. They also require four years of work experience from a reputed firm.

It is estimated that there would be a higher scope for civil engineering jobs in future. Within 2018, the demand for civil engineers may increase and jobs would be offered to a plenty of people. The rapid increase in population has led engineers to build things. Also, in this current modern world old buildings are getting reconstructed as per the trends. Hence within a few years, the construction industry would take the leading business, thereby providing jobs for civil engineers.