The efficacy and stability of an ecosystem remain constant through the flow of energy and matter through it.
Natural Resource
We regard it as a natural resource, which is connected with the existence of this energy and material, the population and ecosystem. That is all the resources that can fulfill the physical and socio-cultural needs of human beings.
As the only main source of energy, the sun regulates natural resources and people directly or indirectly utilize this solar power to make people develop their mechanical civilization.
Some natural resources such as solar energy, water, air, food plants and animals that people collect directly from their environment. But can not use iron, underground water, and other mineral resources directly.
It is the duty of modern people to know about the source, nature of these assets and the nature of the use because otherwise, the overuse and misuse of these assets will result in the destruction of thousands of years of civilization in the near future.
Keeping in mind the huge demand for resources in the coming days, we have to make appropriate plans.
Currently, conventional energy sources meet the demand for 90% of energy from coal, petroleum, natural gas, etc. So, there is a possibility of running out of these non-renewable resources in the near future. Should be more motivated to search and use for Non-renewable resources.
With the use of traditional energy sources and advanced technology, the demand for energy resources will be meet next time.
People need to be more aware of the use of resources. Reservation of assets is an important thing, which will help to meet the needs of the present and the coming days.
The quantity of sanitary sewage or (D.W.F) is determined by considering the following factors:
3 Considering Factors
1. The total quantity of sewage is taken equal to the quantity of water supply.
2. An additional quantity of water is considered for infiltration, commercial and industrial water supply etc.
3. A subtraction is made for ex-filtration, water consumption in drinking, cooking etc.
Thus, the quantity of sanitary sewage = (Total quantity of water )+ (Addition due to infiltration, industrial supply etc.) – (Subtraction due to ex-filtration etc.)
The component parts of a bridge can be broadly categorized as follows:
a) Superstructure
b) Substructure
a) Superstructure
The upper part of a bridge consisting of a structural system in the form of beams, girders, arches, suspension cable & truss etc. is called superstructure. The function of the superstructure is to provide carriageway over which the traffic moves with safety.
b) Substructure
The lower part of a bridge consisting of a structural system in the form of abutments, piers etc. along with their foundation, which supports the superstructure is called substructure. The function of the substructure is to support the superstructure. The substructure of a bridge consists of the following 5 components parts:
1. Approaches
The portions of roadway or railway on both the ends of a bridge are known as approaches. It is provided to enable the vehicle running on roadway or railway at a normal level to approach the bridge floor level.
2. Abutments
The end supports of bridge superstructure are called abutments. Abutments are provided to support the superstructure and to retain the earth pressure on their back.
3. Wing walls
The walls constructed on both sides of abutments to retain the earth of drainage bank and approaches, are called wing walls. Wing walls are provided to protect the drainage bank from erosion.
4. Piers
The intermediate supports of a bridge superstructure are known as piers. Piers are provided when the length of the bridge is more. The functions of piers are:
To take and transfer the load from superstructure to the sub-soil through the foundation.
To divide the length of the bridge into suitable number of spans.
5. Foundation
The lower most part of the bridge substructure is called foundation. The function of the foundation is to transfer the load from superstructure to the sub-soil through the foundation.
Joints form the break in the cement concrete pavement. This causes infiltration of water through them. The infiltration of water through the joints damages the soil sub-grade and the soil slurry ejects out through the joints under heavy wheel loads. This phenomenon is known as mud pumping.
An area is said to be waterlogged when the sub-soil water table comes within 1 m below the ground level.
The following problems and solutions for road construction in the water-logged area:
Problems Of Road Construction In Water Logged Area
The rise of the water table causes a capillary rise of water into the subgrade. With this upward flow of water, the injurious salt such as sulphates, chlorides and carbonates of sodium, calcium and magnesium which are present in the water also rises towards the surface.
These salts increase in volume when they crystallize under a suitable condition. The repeated volume changes of salts due to alternate hydration and dehydration leads to breaking of pavement.
Solution Of Road Construction In Water Logged Area
This problem can be resolved by taking variously measured. One of the most effective measures is to depress the water table. This can be achieved by a system of a sub-surface drain. The other alternative is to keep the road embankment sufficiently high.
The bottom of the pavement should be kept at least 1.5 m above the highest water table. Provision of capillary cutoff placed 0.15 m above the ground level can effectively arrest the rise of water.
Capillary cutoff may be provided in the form of a sand blanket, bituminous stabilized soil. The provision of suitable type and grade of Geotextile over the sub-grade also effectively serves as a cutoff for the capillary rise of water and salt migration. The pavement should also be designed adequately for adverse conditions.
The concrete slump test is done to check the workability of concrete. Following are the slump test theory, limitations, use, procedure, test apparatus, and precautions.
Statement of Problem
i) For M150, 220 litres of total aggregates is required to be used per bag of cement. Slump desired is 50 – 100 mm
Assume fine aggregate to the coarse aggregate ratio as 1:2 using zone II sand.
Keeping FA/CA ratio same, calculate slump when w/c ratio is 0.6, 0.68, 0.75 and state how the slump change with an increase in water.
ii)Keeping W/C ratio at 0.68, FA: CA = 1:2, observe slumps, when the total aggregate is progressively reduced from 220 litres per bag to 200 litres per bag and 180 litres per bag. State how to slump, cohesiveness, and harshness changes with the change in C/A ratio.
iii) Keeping W/C ratio at 0.68, (CA as 50 kg/220 litres) observe slump, cohesiveness and harshness, when FA: CA ratio changes from 1:1, 1:2, 1:3.
State how to slump cohesiveness, and harshness changes with the change in FA: CA ratio.
Note: FA = Fine Aggregates, and CA = Coarse Aaggregates.
Theory
Concrete slump test, which gives a measure of the workability of the mix in terms of a slump. The slump is observed after the subsidence of a concrete mix. The theory of the slump test is described below.
One can get a fairly good idea of cohesiveness by gently tapping the platform on which cone stands. A good cohesive mix subsides further without the coarse aggregate tending to fall out of the mix during tapping.
Harshness can be detected by troweling the mix to obtain a smooth surface. Harsh concrete is usually under sanded and does not give a smooth finish to the surface even with troweling under pressure.
The adequately sanded mix gives a smooth finish with normal troweling. Over sanded mix gives a smooth finish with even light troweling.
Procedure
The procedure of Slump test is described below
Test Apparatus
Following are the test apparatus used for slump test:
Mould in the form of a frustum of a cone.
Tamping rod, 16 mm dia and 0.6 meters long, rounded at one end.
Trough.
Trowel.
G. I. Plain sheets.
Steel Scale.
Image of all apparatus used in concrete slump con test
Concrete slump cone test Apparatus: Slump cone, Tamping rod, Trough, Trowel, G. I. Plain sheets, Steel Scale.
Following are the steps followed during slump test
A) How To Conduct A Slump Test??
a) The internal surface of the mould is thoroughly cleaned and free from superfluous moisture and set concrete, if any, before starting the test.
b) The mould is placed on a smooth, horizontal, rigid and non-absorbent surface such as a fully levelled metal plate.
c) The mould is held firmly in place before the concrete is filled in.
d) Concrete under test is filled in the mould in four layers and each layer is approximately a quarter of the height of the mould. Each layer is tamped with 25 strokes of the round end of the tamping bar. The stroke should be distributed over the entire area of the mould.
Tamped with a tamping rod/bar
e) After the top layer has been filled, the concrete should be struck off level with a trowel or the tamping road so that the mould is exactly filled. All mortar which has leaked between the mould and the base plate is cleaned away.
f) The mould is immediately raised from the concrete slowly and carefully in a vertical direction. This allows the concrete to subside and the slump is measured immediately by determining the difference between the height of the mould and that of the highest point of the specimen being tested in mm.
Video of Concrete Slump Cone Test
B) To Verify The Effects Of FA/CA Ratio, Total Aggregate/Cement Ratio, Observe the Effects Of w/c Ratio On Slump
a) ⇒ Take a suitable proportion, say 1: 2: 4 by volume or by weight.
⇒ Calculate ingredients for a 3 kg batch of cement.
⇒ Make three trials by adding different quantities of water and measure slump and obtain workability, harshness, and cohesiveness.
⇒ It will be found that more the amount of water used, greater is the slump. Conversely, in the field, a sudden increase in slump indicates the increase in water contents if other factors remain constant and water has to be changed accordingly.
b)
Given constant w/c ratio and constant total aggregate-cement ratio, observe the effect of F.A/C.A ratio on the slump.
⇒ Assume (suitable) proportions.
⇒ determine the ingredients for 3 kg batch of cement.
⇒ Make three trials by keeping w/c and total aggregate/cement ratio same, but by varying F.A/C.A ratio and observe slump and workability, harshness and cohesiveness.
⇒ It will be observed that deficiency in F.A tends to segregate the concrete and more percentage of F.A requires more water for obtaining the desired slump.
⇒ In the field, if the slump test indicates segregating tendency, it means that the aggregate is deficient in fines. Or if the water is required for the desired slump, it means there is an excess of fine aggregate.
c)
Given the constant W/C ratio and F.A./C.A. ratio, observe the effect of the A/C ratio on the slump.
⇒ Select a suitable proportion by volume or by weight.
⇒ Calculate ingredients for a 3 kg batch of cement.
⇒ Keeping W/C constant and F.A./C.A. ratio constant, make three trials by varying the total quantity of aggregate.
⇒ Measure slump in each case and observe workability.
⇒ It will be observed that smaller the A/C ratio, greater is the slump. In the field, if the slump test starts indicating greater slump, check on batching has to be done to verify that proper quantities are added as per design.
Precautions
a) The test shall be carried out at a place free from vibrations or shocks and within a period of two minutes after mixing if it is a field test. For laboratory test, reliable results corresponding to site conditions can be had if the slump test is carried out 10 minutes after mixing.
b)If slump collapses or shears off laterally, the test may be repeated, and if again same results are obtained, the fact should be recorded and slump measured.
c)For a laboratory test, it is better to convert all quantities into weight by multiplying the volume by bulk densities. In the absence of exact data, assume bulk densities from 1.5 to 1.6 for F. A. and 1.6 for C. A.
Limitation
The limitations of the slump test are as follows:
Because of its simplicity in performing the experiment and its sensitivity to changes in the moisture content of the successive intended identical mixes, it is widely used in the field for judging the workability.
This test has limitations. Slump observed strictly, speaking has no relation to useful internal work required for full compaction.
Also, a significant variation can be obtained with the same concrete.
Three types of slumps are obtained:
a) True slump
b) Shear slump
c) Collapse slump
Collapse slump is usually obtained with lean harsh or very wet mixes. It is difficult to measure a slump when the shear slump is obtained.
Generally, concrete giving shear or collapse slump is considered unsatisfactory for placing. The above Fig shows the different types of slumps obtained. Rich mixes normally behave better than lean dry and very wet mixes.
Choice Of Slump
The slump observed during the test is required to be compared to -some standard value of slumps considered desirable for various types of placing and vibrating conditions.
The basically higher slump is chosen when vibration is done manually, sections are small are heavily reinforced. Also greater the nominal size of aggregate, more slump is preferred.
Based on the experience and experiments, various authorities such as Concrete Association of India, P.C.A. Illinois, have suggested values of slumps and are reproduced in part I. Out of all the data given, the one given by McIntosh is more comprehensive.
The table gives the range of slumps to be aimed at. As a rule, lower limits of the ranges are preferable. But in case of difficult placing conditions, it is better to aim at the higher limit of the range.
Use Of Slump Test
The slump test of concrete is very useful on-site to keep the check on a day-to-day, hour-to-hour variations in the materials fed into the mixes.
An increase in slump may indicate an unexpected increase in the moisture content of aggregate. Or it may indicate a change in gradient of aggregate, e.g. deficiency of sand, or change in the shape of the aggregate.
Too-high or too-low slump gives immediate warning to the operator and enables him to remedy the situation.
For dry mixes with very low Water/Cement ratios, the slump test gives zero slumps and is not useful for high strength concrete. This test should not be used to compare workability of mixes of different proportions or types of aggregate as the results might be misleading.
Recommended Value of Slump For Various Construction Works
Following are the recommended value of slump for different types of construction works:
Sl. No
Types of Construction Works
Value of Slump
1.
Heavy mass construction
25mm to 50mm
2.
Pavements works
25mm to 50mm
3.
Un-reinforced footing, caissons, and sub-structure walls
