What is paving brick?
The bricks are easily procurable in several localities and they are made of uniform quality and hard enough to resist the wear and impact of traffic, they can be made use of as a good pavement material for brick pavement.
The bricks at present have become the popular type of pavement as they are easily available. The remaining types came along as necessitated from time to time by character and volume of traffic.
In this chapter, here we discuss, the common varieties of brick pavers with respect to their method of construction, suitability, and other related aspects.
Advantage of Brick Pavement
In general, it can be stated that Brick pavements are specially sited for carrying exceptionally heavy traffic and in addition, they offer the following advantages also:
- The maintenance cost is low.
- They are durable and have excellent wear resisting property.
- They are easy to repair.
- They possess high resistance to skidding
Disadvantage of Paving Bricks
They provide a nice foothold for the pedestrians and the animals. However, these pavements have the following disadvantages:
- The initial cost is comparatively high.
- The presence of moisture or water may cause slipperiness, greasiness and mud-splashing in some cases.
- There may be swelling and decay in wet weather for some types of pavements.
- They produce excessive noise due to rattling of iron-tyres.
Can you use regular bricks as pavers?
Apart from the conventional types of low cost roads, stabilized ds, bituminous roads and cement concrete roads, some other types of pavements are considered to be suitable in certain urban s like warehouses, market places, busy streets, bridges or tunnels provided within the city limit to relieve traffic congestion.
The materials used for these pavements include bricks or locks made from stones, wood, asphalt, cast-iron, rubber, etc. Out of these materials, the stone blocks are the oldest and even today, they are being used at some places.
Characteristics of Brick Paving
The brick pavements possess in particular various characteristics and they can be enumerated as follows
- attractive in appearance:
- can be laid with the least camber;
- Cheap to maintain:
- easy to clean,
- easy to repair and reinstate after laying of pipes,
- freedom from skidding:
- improving in performance with use;
- not influenced by climate;
- practically noiseless;
- possessing perfect drainage and rapidity of drying,
- providing perfect foothold; civi requiring the lowest tractive force
- suitability for gradients:
- wearing uniformly:
- yield no mud or dust; etc.
For the purpose of convenience, the brick pavements can be classified in the following three categories:
- Brick and block pavement
- Vitrified brick pavement
- Brick edging
(1) Brick and block pavement:
The pavement is constructed either of ordinary bricks or specially moulded bricks in the form of blocks of generally cubical shape. The length of block is less than that of a standard brick, but its width and depth are comparatively greater than those of a standard brick.
Fig. 2. shows the section of a typical brick and block pavement. The construction procedure is carried out in the following stages:
- Preparation of subgrade:
The subgrade may be in cutting or embankment. It is brought to the desired camber and grade and then compacted by a 10-tonne roller. The width of the bed to receive the base or sub-base course is generally 150 mm more on either side than the width of the pavement.
- Preparation of the foundation or base course:
Depending upon the climatic conditions, type of traffic, nature of soil and availability of materials, the base course is prepared of any one of the following materials:
- water bound macadam base of about 150 mm thickness; or
- blast furnace slag of 150 mm to 200 mm thickness: or
- Cement concrete base of 100 mm to 150 mm thickness.
The cement concrete base is the most popular and widely used base as it helps in bridging the soft spots in a poorly drained sub-soil and it also possesses greater compressive strength which makes it possible to construct a thinner concrete foundation as compared to any other type under similar conditions. Sometimes it is also provided with mesh reinforcement to avoid the formation of cracks.
- Placing of the cushion:
It is necessary to cover the base course with a cushion or bedding course of about 20 mm to 25 mm thickness to take care of the Irregularity of the sizes of blocks and to help in spreading the load uniformly.
Following materials available being used as cushion:
This material largely used because easily available and cheap. Does not give satisfactory performance.
- Dry mix of cement and sand:
The cement and sand are mixed in dry state in proportion 1:4 and it is used as cushion in dry condition. This material is quite satisfactory, but it is costly.
- Granulated slag:
If easily available, the granulated slag when used as cushion, sets up in due course of time and it is considered to be a satisfactory material for bedding course.
- Sand-bitumen mix:
The sand is mixed with light tar or cutback bitumen and the mixture is spread evenly, rolled with a light tandem roller and finally brought to true camber and gradient. The blocks are then embedded on this water-proof cushion which will not shift.
Laying, rolling and pattern of Brick paving:
The blocks are hand-laid and placed as closely as possible. The work of laying the blocks is started from the Kerbs on either side and its pattern is progresses towards the centre-line of road. The precautions to be taken are as follows:
(a) The laying of blocks is done in straight parallel courses.
(b) The blocks in one row should break joints with the blocks in the next row by at least 75 mm.
(c ) If the blocks are not cubical, the long dimension should be laid perpendicular to the kerb.
- The blocks are usually laid in position with the help of templates for giving the desired camber. When sufficient length of pavement has been laid, the rolling with light tandem roller is started from the edges and progressed towards the crown.
The rolling is continued till the blocks are firmly and evenly bedded and no further settlement is noticed.
In case of local depressions, the blocks in that portion are taken out, relaid and rolled.
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The joints between the adjacent blocks have pt to be filled up with suitable material capable of preventing the lateral and vertical motions of the blocks under heavy wheel loads, intercepting the flow of water in the joints, facilitating easy cleaning of the pavement, and providing a uniform riding surface.
The materials which are commonly used for joint filling are as follows:
(a) Sand: This material is cheap and as it is liable to be displaced easily, it does not fulfil any of the above requirements and its performance is quite unsatisfactory.
(b) Cement sand slurry: If a thin slurry of cement and sand mixed in equal proportions is used as joint filler, it protects the edges of blocks in addition to other necessary requirements of a filler. This material is seldom used because of its three drawbacks:
- It requires comparatively large quantity of grout and hence, it proves to be costly.
- It becomes rigid after hardening and does not allow for expansion or contraction. Hence, under extreme hot weather conditions, the pavements are likely to buckle, heave, arch or blow-up.
- It requires at least 10 to 12 days for setting and hardening so that no traffic can be permitted during this period.
(c) Asphalt filler:
The asphalt filler may be used with or without sand. It probably fulfils all the requirements of a filler except that it does not adequately protect the edges of blocks. For successful work, the pavement should be clean, dry and care should be taken to avoid the overheating of asphalt before application.
The filling of the joints is not done individually. But the entire surface of the pavement is covered with the filler material. The excess binder material after the joints are completely filled can be removed and re-used, if before applying the binder, some stripping or separating agent such as calcium chloride solution or whitewash has been coated on the block surface.
(2.) Vitrified brick pavement:
For heavy traffic requirements, the vitrified bricks are sometimes used. These bricks are made in Standard sizes from fine clay or shale heated in a kiln to 1100°C at which the particles fuse together.
It is followed by slow cooling for about 3 to 4 days. The main drawback of this pavement is gh initial cost, but it is greatly compensated by the various advantages afforded by this type of pavement, especially of its long life of service and very little maintenance cost.
A minimum compressive strength of the order of 500 kg/cm2 to 600 kg/cm2 may generally be expected of bricks selected for this type of pavement. The base course is preferably provided of plain cement concrete with a cushion of 20 mm thick sand-bitumen.
The cushioning layer is rolled with light road roller and the bricks are laid either flat or on edge. The joints are usually filled with the bituminous filler and before filling the joints, the pavement is compacted by means of light road roller. The final rolling should preferably be done by working the rollers on wooden planks laid over the pavement to avoid the breaking of edges of the bricks.
(3.) Brick edging:
For widening the main carriageway, the brick edging provides a cheap and effective method, as shown in fig. 3. The extra 600 mm width of flat bricks or bricks on the edge on either side of the carriageway provides an additional traveling surface.
Construction process of Brick Pavement (Paving Process of brick)
Followings are the construction process of brick pavement:
- The bricks in required quantity are collected and stacked on berms.
- The shoulders are excavated along the trench to the necessary depth to receive the bricks.
- The cushioning layer of sand is provided with a thickness of about 25 mm.
- The bricks are laid in such a way that its top surface forms a continuous surface with the edge of the main carriageway both in respect of grade and camber.
- Finally the sand layer of 20 mm thickness is spread to fill up the joints and the surface is rolled with light road roller.
The extended pavement formed by brick edging does not form the main travelling surface. But it certainly assists in considerably improving the traffic carrying capacity of the road.
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