Practical knowledge of civil engineering: January 2021

Monday, January 25, 2021

What is lime and there types

It is a significant restricting material utilized in building development. Lime has been utilized as the material of development from antiquated time. At the point when it is blended in with sand it furnishes lime mortar and when blended in with sand and coarse total, it structures lime concrete.

Types of Limes and their Properties

The limes are named fat lime, Hydraulic lime and poor lime:

(I) Fat lime: It is made out of 95 levels of calcium oxide. At the point when water is added, it slakes

vivaciously and its volume increments to 2 to 2 half times. It is white in shading. Its properties are:

(a) solidifies gradually

(b) has a serious level of versatility

(d) white in shading

(e) slakes enthusiastically.

(ii) Hydraulic lime: It contains earth and ferrous oxide. Contingent on the level of mud present, the water driven lime is partitioned into the accompanying three sorts:

(a) Feebly hydraulic lime (5 to 10% earth content)

(b) Moderately hydraulic lime (11 to 20% dirt substance)

The properties of water driven limes are:

• Sets submerged

• Color isn't entirely white

• Forms a meagre glue with water and don't disintegrate in water.

• Its coupling property improves if its fine powder is blended in with sand and kept as stack for seven days, prior to utilizing.

(iii) Poor lime: It contains over 30% mud. Its tone is sloppy. It has helpless restricting property.nThe mortar made with such lime is utilized for mediocre works. IS 712-1973 characterizes lime as class A, B, C, D and E.

Class A Lime: It is predominantly water-powered lime. It is typically provided as hydrated lime and is usually utilized for underlying works.

Class B Lime: It contains both water powered lime and fat lime. It is provided as hydrated lime or as speedy lime. It is utilized for making mortar for workmanship works.

Class C Lime: It is predominantly fat lime, provided both as speedy lime and fat lime. It is utilized for completing coat inputting and for whitewashing.

Class D Lime: This lime contains a huge amount of magnesium oxide and is like fat lime. This is additionally regularly utilized for whitewashing and for completing coat inputting.

Class E Lime: It is a tainted limestone, known as kankar. It is accessible in measured and square structure. It is provided as hydrated lime. It is usually utilized for brickwork mortar.

Types of bricks,

Classification of Bricks Based on their Quality

The bricks used in construction are classified as:

(i) First class bricks

(ii) Second class bricks

(iii) Third class bricks and

(iv) Fourth class bricks

(i) First Class Bricks: These bricks are of standard shape and size. They are burnt in kilns. They fulfill all desirable properties of bricks.

(ii) Second Class Bricks: These bricks are ground moulded and burnt in kilns. The edges may not be sharp and uniform. The surface may be some what rough. Such bricks are commonly used for the construction of walls which are going to be plastered.

(iii) Third Class Bricks: These bricks are ground moulded and burnt in clamps. Their edges aresomewhat distorted. They produce dull sound when struck together. They are used for temporary and unimportant structures.

(iv) Fourth Class Bricks: These are the over burnt bricks. They are dark in colour. The shape is irregular. They are used as aggregates for concrete in foundations, floors and roads.

Thursday, January 21, 2021

Test on cement

Physical Tests on Cement

a) Soundness Test: It is led by strainer investigation. 100 gms of concrete is taken and sieved through IS sifter No. 9 for fifteen minutes. Buildup on the sifter is gauged. This ought not surpass 10% by weight of test taken.

(b) Setting Time: Initial setting time and last setting time are the two significant physical poperties of concrete. Beginning setting time is the time taken by the concrete from adding of water to the beginning of losing its pliancy. Last setting time is the time passed from adding of the water to finish loss of versatility. Vicat device is utilized for finding the setting times fig

Vicat contraption comprises of a portable bar to which any of the three needles appeared in figure can be appended. A pointer is joined to the versatile pole. A vicat shape is related with this contraption which is as part chamber. Prior to discovering beginning and last setting time it is important to decide water to be added to get standard consistency. For this 300 gms of concrete is blended in with about 30% water and concrete glue arranged is filled in the shape which lays on non permeable plate. The unclogger is joined to the mobile pole of vicat device and tenderly brought down to contact the glue in the shape. At that point the unclogger is permitted to move uninhibitedly. On the off chance that the entrance is 5 mm to 7 mm from the lower part of the form, at that point concrete is having standard consistency. If not, try is rehashed with various extent of water fill water needed for standard consistency is found. At that point the tests for introductory and last setting times can be done as clarified underneath:

Intial Setting Time: 300 gms of concrete is altogether blended in with 0.85 occasions the water for standard consistency and vicat shape is totally filled and top surface is leveled. 1 mm square needle is fixed to the pole and delicately positioned over the glue. At that point it is openly permitted to infiltrate. In the first place the needle infiltrates the glue totally. As time slips by the glue begin losing its pliancy and offers protection from entrance. At the point when needle can infiltrate up to 5 to 7 mm above lower part of the glue analyze is halted and time passed between the expansion of water and end if the analysis is noted as beginning setting time.

Final Setting Time. The square needle is supplanted with annular collar. Trial is proceeded by permitting this needle to uninhibitedly move after delicately contacting the outside of the glue. Time slipped by between the expansion of water and the sign of needle yet not of annular ring is found on the glue. This time is noted as conclusive setting time.

c) Soundness Test: This test is led to discover free lime in concrete, which isn't alluring. Le Chatelier device appeared in Fig. 1.6 is utilized for leading this test. It comprises of a split metal form of width 30 mm and tallness 30 mm. On one or the other side of the split, there are two markers, with pointed finishes. The closures of pointers are 165 mm from the focal point of the mould.Properly oiled Le Chatelier form is put on a glass plate and is filled totally with a concrete glue having 0.78 occasions the water needed for standard consistency.

It is then covered with another glass plate and a little weight is set over it. At that point the entire get together is held submerged for 24 hours. The temperature of water ought to be somewhere in the range of 24°C and 50°C. Note the distance between the pointer. At that point place the shape again in the water and warmth the get together with the end goal that water arrives at the limit shortly. Heat up the water for 60 minutes. The shape is taken out from water and permitted to cool. The distance between the two pointers is estimated. The contrast between the two readings demonstrate the development of the concrete because of the presence of unburnt lime. This worth ought not surpass 10 mm.

(d) Crushing Strength Test: For this 200 gm of concrete is blended in with 600 gm of standard sand affirming to IS 650–1966. Subsequent to blending completely in dry condition briefly refined consumable water P/4+ 3 rate is added where P is the water needed for the standard consistency. They are blended in with scoop for 3 to 4 minutes to get uniform combination. The blend is set in a solid shape form of 70.6 mm size (Area 5000 mm2) kept on a steel plate and pushed with 25 mm standard steel bar multiple times inside 8 seconds. At that point the form is set on a standard vibrating table that vibrates at a speed of 12000 ± 400 vibration for every moment. A container is made sure about at the top and the excess mortar is filled. The form is vibrated for two minutes and container eliminated. The top is done with a blade or with a scoop and leveled. Following 24 ± 1 hour shape is taken out and block is set under clean water for relieving. After determined period shapes are tried in pressure testing machine, keeping the example on its level edges. Normal of three 3D squares is accounted for as pulverizing strength. The compressive strength toward the finish of 3 days ought not be under 11.5 N/mm2 and that toward the finish of 7 days at least 17.5 N/mm2.

Tuesday, January 19, 2021

Types of Cement

In addition to ordinary portland cement there are many varieties of cement. Important varieties are briefly explained below:

(i) White Cement: The cement when made free from colouring oxides of iron, manganese and chromium results into white cement. In the manufacture of this cement, the oil fuel is used instead of coal for burning. White cement is used for the floor finishes, plastering, ornamental works etc. In swimming pools white cement is used to replace glazed tiles. It is used for fixing marbles and glazed tiles.

(ii) Coloured Cement: The cements of desired colours are produced by intimately mixing pigments with ordinary cement. The chlorium oxide gives green colour. Cobalt produce blue colour. Iron oxide with different proportion produce brown, red or yellow colour. Addition of manganese dioxide gives black or brown coloured cement. These cements are used for giving finishing touches to floors, walls, window sills, roofs etc.

(iii) Quick Setting Cement: Quick setting cement is produced by reducing the percentage of gypsum and adding a small amount of aluminium sulphate during the manufacture of cement. Finer grinding also adds to quick setting property. This cement starts setting within 5 minutes after adding water and becomes hard mass within 30 minutes. This cement is used to lay concrete under static or slowly running water.

(iv) Rapid Hardening Cement: This cement can be produced by increasing lime content and burning at high temperature while manufacturing cement. Grinding to very fine is also necessary. Though the initial and final setting time of this cement is the same as that of portland cement, it gains strength in early days. This property helps in earlier removal of form works and speed in construction activity.

(v) Low Heat Cement: In mass concrete works like construction of dams, heat produced due to hydration of cement will not get dispersed easily. This may give rise to cracks. Hence in such constructions it is preferable to use low heat cement. This cement contains low percentage (5%) of tricalcium aluminate (C3A) and higher percentage (46%) of dicalcium silicate (C2S).

(vi) Pozzulana Cement: Pozzulana is a volcanic power found in Italy. It can be processed from shales and certain types of clay also. In this cement pozzulana material is 10 to 30 per cent. It can resistaction of sulphate. It releases less heat during setting. It imparts higher degree of water tightness. Its tensile strength is high but compressive strength is low. It is used for mass concrete works. It is also used in sewage line works.

(vii) Expanding Cement: This cement expands as it sets. This property is achieved by adding expanding medium like sulpho aluminate and a stabilizing agent to ordinary cement. This is used for filling the cracks in concrete structures.

(viii) High Alumina Cement: It is manufactured by calcining a mixture of lime and bauxite. It is more resistant to sulphate and acid attack. It develops almost full strength within 24 hours of adding water. It is used for under water works.

(ix) Blast Furnace Cement: In the manufacture of pig iron, slag comes out as a waste product. By grinding clinkers of cement with about 60 to 65 per cent of slag, this cement is produced. The properties of this cement are more or less same as ordinary cement, but it is cheap, since it utilises waste product. This cement is durable but it gains the strength slowly and hence needs a longer period of curing.

(x) Acid Resistant Cement: This cement is produced by adding acid-resistant aggregated such as quartz, quartzite, sodium silicate or soluble glass. This cement has good resistance to action of acid and water. It is commonly used in the construction of chemical factories.

(xi) Sulphate Resistant Cement: By keeping the percentage of tricalcium aluminate C3A belowfive per cent in ordinary cement this cement is produced. It is used in the construction of structures which are likely to be damaged by alkaline conditions. Examples of such structures are canals, culverts etc.

(xii) Fly Ash Blended Cement: Fly ash is a byproduct in thermal stations. The particles of fly ash are very minute and they fly in the air, creating air pollution problems. Thermal power stations have to spend lot of money to arrest fly ash and dispose safely. It is found that one of the best way to dispose fly ash is to mix it with cement in controlled condition and derive some of the beneficiary effects on cement. Now-a-days cement factories produce the fly ash in their own thermal stations or borrow it from other thermal stations and further process it to make it suitable to blend with cement. 20 to 30% fly ash is used for blending.

Tuesday, January 12, 2021

Water Absorption test for bricks

water absorption test on bricks

Saturday, January 2, 2021

20x40 ka naksha

2 BEDROOM 1 HALL 1KITCHEN 1 PORCH 2 ATTACH TOILET STAIRS

https://youtu.be/kAwgjZVm44s

Practical knowledge of civil engineering