What is aggregate base course used for?
Aggregate Base is used as the base course under asphalt pavement roadways, under concrete slabs and structural foundations, and as backfill material for underground pipelines and other underground utilities within a roadway.
What are the functions of granular base course?
The granular subbase forms the lowest (bottom) layer of the pavement structure, and acts as the principal foundation for the subsequent road profile, provides drainage for the pavement structure, and protects the structure from frost.
What can crushed rock be used for?
Crushed stone is used mostly as aggregate for road construction and maintenance. It is also used for making cement and lime and other chemical applications, and in agriculture. There are other uses for crushed stone, many of which are not accurately or completely reported.
What is stone base in road construction?
The base layer forms the foundation for the road surface The bottom layer essentially comprises an unbound mixture of coarse and fine crushed stone, as well as crushed sand, to achieve the desired load-bearing capacity and absorb traffic loads so that the underlying subgrade is not deformed.
What is the difference between sub base and base course?
Base may consist of unbound materials, such as gravel or crushed stone, or stabilized materials, such as asphalt-, cement- or lime-treated materials. The subbase course is typically a granular borrow that is placed between the base and subgrade. It can be constructed as either a treated or untreated layer.
Why do we put base course material under rigid pavement?
Base Course It provides (1) additional load distribution, (2) contributes to drainage and frost resistance, (3) uniform support to the pavement and (4) a stable platform for construction equipment (ACPA, 2001). Bases also help prevent subgrade soil movement due to slab pumping.
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.
Why is GSB called drainage layer?
GSB or granular sub-base prevents capillary water from rising; its particle size is so designed that the capillary action stops and cant go beyond GSB layer. Secondly, it works like a drainage layer where water can pass without damaging other road layers.
What is the difference between gravel and crushed rock?
Crushed stone often has an angular and jagged edge that occurs during the crushing process. Gravel, on the other hand, typically has a very smooth texture and surface because of the natural weathering and wear of being exposed to the effects of running water.
What is the best rock to use for drainage?
gravel
For the best drainage, look for coarse washed rock (gravel) that is screened, with a stone size of 1/2 to 3/4 inch. Smaller rock with fine particles could clog the holes of the drain pipe. Pea stone works, but the smooth stones settle together and don’t move as much water as coarse rock.
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 screening in road construction?
Screening. A screening is a construction material used in WBM road construction work to fill the void or space left between aggregate particles after compaction is done. Generally, construction materials used for screening purposes have smaller sizes compared to coarse aggregate.
What is coarse crushed stone used for in construction?
Coarse Coarse aggregates consist of gravel, crushed stone or recycled concrete with particle sizes of ranging from 3/8-inch to 1.5 inches. Coarse aggregates are used in a wide range of construction applications, notably in concrete and asphalt mixes. Common uses for coarse crushed stone
What is the best grade of crushed stone for construction?
#1 – The # 1 crushed stone grade is the largest of the crushed stone grades and includes stone between 2-4 inches long. This material is great for larger jobs or for filling in larger holes. #3 – This size of the stone ranges from 1/2 to 2 inches long. This material is a great choice for railroad projects and those that require drainage.
What is the screening process for crushed stone?
The screening process starts by removing larger stones, then medium stones, and eventually goes all the way down to the stone dust. This screening is important because contractors need very specific types of crushed stone to complete different types of projects.
What are crushed stone aggregates?
Crushed stone aggregates are produced by crushing quarried rock, then screening it to sizes appropriate for the intended use.