What is the minimum thickness of subgrade?

What is the minimum thickness of compacted sub grade? Explanation: The minimum thickness of sub grade required is 300mm and in highways it is 500 mm as they are provided with the maximum best facilities.

What is the thickness of subgrade?

Subgrade

Subgrade is the bottom most layer which is nothing but natural soil layer compacted up to required depth generally about 150 to 300 mm to receive the loads coming from top layers. This layer is termed as foundation for the pavement system.

What is the minimum thickness of pavement?

➢The thickness of sub-base should not be less than 150 mm for design traffic less than 10 msa and 200 mm for design traffic of 10 msa and above. ➢The recommended minimum thickness of granular base is 225 mm for traffic upto 2 msa and 250 mm for traffic exceeding 2 msa.

Which is the minimum thickness used in bituminous macadam?

6. What is the minimum thickness used in bituminous macadam? Explanation: The pavement used in bituminous Macadam is usually of a thickness of 50mm and maximum is 100 mm. Explanation: The interface between the existing pavement and new pavement can be provided by using tack coat.

What is a good subgrade?

A subgrade should be thick enough to withstand the loads acting upon it. The heavier the loads, the thicker the subgrade should be, as you might have subgrades as thick as 12 inches and event thicker, normally for highways.

subgrade technical specification | dry density of soil | mdd, compaction, ll p.l CBR of soil index |

What is subgrade soil strength?

Subgrade materials are typically characterized by (1) their resistance to deformation under load, in other words, their stiffness or (2) their bearing capacity, in other words, their strength.

What is the minimum subgrade CBR for a road construction?

CBR value is taken at 2.5mm & 5 mm penitration. in subgrade material CBR value should be nearly 15-19% .

What is subbase material?

In this publication, a subbase is defined as the layer of material that lies immediately below the concrete pavement. Some engineers call this a base course since that term is used to designate the first layer beneath an asphalt surface.

What is BM and BC road?

DBM (Dense Bituminous Macadam) & BC (Bituminous Concrete) are the top most layers of an Bituminous Top Roads, whose thickness is determined my MSA & CBR. CBR- California Bearing Ratio is a method of determining the mechanical strength & Load bearing capacity of soil.

What is WBM road?

WBM road means water bound macadam road. The wearing surface of WBM road consist of clean and crushed aggregates which are mechanically interlocked by rolling operation. The material is bound with filler material (which are also called as screenings) and water, laid on prepared base course.

What is the maximum thickness of a subgrade layer?

The maximum particle size in the Embankment and Subgrade soils are 75mm and 50mm respectively according to clause 305.2.

What is the minimum thickness of slab?

Minimum thickness should not be less than 4.75 inches not forgetting the factor of safety. Standard concrete floor slab thickness in residential construction is 4 inches, five to six inches is recommended if the concrete will receive occasional heavy loads, such as mortar homes or garbage trucks.

What is the thickness of pavement?

The selection of the pavement and gravel thickness is based on three criteria (Figure 3): (1) the thickness of the asphalt pavement is 0.1 m and the gravel base thickness is 0.2 m, which is shortened to 10 to 20 types; (2) the thickness of the asphalt pavement is 0.18 m and the gravel base thickness is 0.2 m, which is ...

What is a subgrade material?

In transport engineering, subgrade is the native material underneath a constructed road, pavement or railway track (US: railroad track). It is also called formation level.

What is a subgrade in construction?

Subgrade is that portion of the earth roadbed which after having been constructed to reasonably close conformance with the lines, grades, and cross-sections indicated on the plans, receives the base or surface material. In a fill section, the subgrade is the top of the embankment or the fill.

What is prepared subgrade?

The foundation of the pavement structure is known as subgrade. Preparation of subgrade consists of all operations before the pavement structure could be placed over it and compacted. The subgrade may be situated on an embankment or excavation or at the existing ground surface.

What is PQC in road construction?

Pavement Quality Concrete (PQC) is normally employed for providing a strong surface of rigid pavements. PQC is also used for construction of runways in airports in order to distribute the heavy impact load from wheel to sub- grade layers [1].

What is DBM layer?

Engineering. Dense Bituminous Macadam (DBM) is a binder course used for roads with more number of heavy commercial vehicles and a close-graded premix material having a voids content of 5-10 per cent.

What is the temperature of DBM?

The temperature of the mix at the time of laying shall not be less than 120°C, minimum. The mix shall be placed in full width of the pavement. The compacted thickness of any DBM layer shall be as per the specification.

Which soil is best for subgrade?

A clayey soil generally has a low CBR value (less than 8). Sands are more granular and drain better and will generally have CBR values between 15 and 35. Gravel will have the best CBR values, generally 25 and up. That is why it is suggested to save the best material to cap the subgrade.

What is a subgrade layer?

The sub-grade layer of a pavement is, essentially, the underlying ground. It is also known as the "Formation Level", which can be defined as the level at which excavation ceases and construction starts.

How do you prepare subgrade?

Construction Methods

The subgrade shall be prepared in lengths of not less than 100 metres at any one time, unless otherwise approved by the Engineer. Subgrade material shall be scarified to a depth of 150 mm until the soil is fully loosened. Any lumps or clods shall be removed or broken to pass a 50 mm sieve.

What is a good CBR value for subgrade?

It is crucial for highway engineers to develop a subgrade with a California Bearing Ratio (CBR) value of at least 10. Research has shown that if a subgrade has a CBR value less than 10, the subbase material will deflect under traffic loadings in the same manner as the subgrade and cause pavement deterioration.

What is subgrade CBR?

The California Bearing Ratio (CBR) is a measure of the strength of the subgrade of a road or other paved area, and of the materials used in its construction. The ratio is measured using a standardized penetration test first developed by the California Division of Highways for highway engineering.

What is the size of GSB?

GSB :- Granular sub base or GSB is a typical layer adopted in highway construction, which is laid above the subgrade and below the crust materials. Naturally available material consisting of various grades may be used for GSB, the largest grain size up to 65mm.