How many grades are there in GSB?

Out of six GSB grades Grade III, Grade IV, Grade V and Grade VI obtained permeability values are more than predicted values.

Is code of GSB grading?

Grading for Granular Sub-base Materials (GSB) (Grading – IV) IS:2386 (Part-I)

What is the rate of GSB?

Gray Granular Sub Base (GSB), For Construction, Rs 32 /cubic feet Sri Guru Enterprises | ID: 20391030730.

What is GSB material?

Granular Sub-base (GSB) consists of laying and compacting well graded material on prepared sub-grade in accordance with the specifications.: GSB layer is intermediate layer in between Sub-grade and Wet mix macadam. GSB layer is laid in roads and higway works due to its properties .

What is minimum thickness of GSB?

➢The recommended minimum thickness of granular base is 225 mm for traffic upto 2 msa and 250 mm for traffic exceeding 2 msa.

How do I test GSB?

MDD of the GSB material is found to be 2.1 g/cc at an OMC of 3.3%. CBR Value: To know the strength of GSB, CBR test is conducted on GSB granular mix as per IS 2720-pt 16 under soaked conditions. The CBR value at 2.5 mm penetration level is found out to be 31%.

What is DBM in civil 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 GSB density?

Density. 2.1 g/cc. We are specialized in offering GSB Aggregate to our customers.

How is GSB laid?

The GSB Material is spread with the help of motor grader on the approved layer of Sub-grade in single layer of 200 mm with Grading either IV or V. During spreading and mixing by grader in site, water is sprinkled over the material by water browser mounted on water tanker.

What is the minimum thickness of subgrade?

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 effective CBR?

Composite strength of the subgrade and the embankment soil below it is termed as EFFECTIVE CBR. ▪ This composite strength should be taken for design consideration ▪ This composite strength should be taken for design consideration rather than strength of top 500mm.

What is GSB and WMM?

WMM = Wet Mix Macadam (40 mm down aggregates, mix design required) GSB = Granular Sub Base (63 – 40 mm aggregate or 70mm down aggregates) SR = Soil Replacement (preferably quary materials)

How is the permeability of GSB gradations measured?

Veeraragavan have reported comparable values of laboratory measured permeability of all six GSB gradations given in the MORT&H (4threvision) speculations. The permeability values obtained in terms of coefficient of permeability of GSB mixes are less than 3.17 m/d indicating that these mixes cannot be used for subsurface drainage purpose.

How to grade granular sub base materials ( GSB )?

In order to prevent binding of the sieve apertures by overloading, the amount of aggregate placed on each sieve shall be such that the weight of the aggregate retained on the sieve at completion of the operation is not greater than the value given for that sieve in Table-III.

What should be rolled before laying GSB material?

Prior to laying of GSB material, the sub-grade already finished to clause: 301 or 305 of MORT&H as applicable shall be prepared. Approved sub-grade layer is rolled with two passes by smooth wheel roller with slight sprinkle of water.

What kind of material is used in GSB?

The material used in GSB shall be mixture of natural sand, moorum, gravel, crushed stone in specified grading given in Table 400‑1.Crushed slag, crushed concrete, brick ballast and kankar can also be used on the prior approval of the Engineer or competent authority. It shall be free from organic or other deleterious materials.