Grade Beams Construction
Grade Beams Construction
A grade beam is a component of a building foundation which helps to transmit the load from bearing wall into foundations. It contains reinforced concrete beams and is applied in situations where the load-bearing capacity of surface soil is less than predicted design loads. They are different from a wall footing as it is constructed for bending but wall footing transmits the weight of the wall directly in the ground. It is also different from strap beam as grade beams are reinforced to transmit the load of the wall to foundations but strap beam is constructed to redistribute the weight of a column between the footings.
Grade Beam Construction Process
There are various steps which are involved in construction process of this type of beam which are described below:
- The preparation and excavation for grade beams should be done. Excavation of trenches is executed for the beams on the basis of its level. We can also construct these beams on the ground directly and in this case the ground surface is leveled and prepared.
- We should install a framework for grade beams. After the preparation and excavation is finished, then according to the dimensions of the beam forms is placed. If we have constructed these beams on the ground, then the bottom of the forms is placed earlier to its sides. The reinforcement cage is kept on the flat soling brick before we fix side shuttering. The construction of the framework is the same as that of conventional beams when grade beam is constructed above the ground. Hence, we must place shutters for the bottom and both sides of the grade beam. After the finalization of beam framework, the designated grade beam dimensions should be supplied which should contain enough reinforcement cover.
- Then the reinforcement of the grade beam should be placed. The reinforcement detailing is provided in structural drawing like size and number of longitudinal reinforcements and its required length, number and spacing of stirrups. The number and size of top, bottom and extra reinforcements, lap length and placement, spacers, hooks and clear reinforcement cover must be checked.
- At last we pour concrete for the grade beam. We can put ready mix concrete or on-site machine-mixed concrete. We can remove the side-shutter of beam 24 hours after pouring concrete. But we can remove the bottom shutter only after concrete gains its strength. Depending upon the time span of the beam, we can determine the time duration for removing the bottom shutter.