Foundation Repair and Strengthening Techniques- Bismin Babu

Contents

Need for Repair & Strengthening Damages & Repair Methods

House Leveling Piering Underpinning

Bulged Foundation Walls Pilasters Steel I Beams or U Channel Foundation Anchors Reinforcing Sister Walls

Vertical Foundation Movement Mud Jacking or Grout Pumping Polymer Injection

Need for Repair & Strengthening The main purpose of foundation repair is to carry out structural repairs to

load bearing elements.

It may involve cutting portions of the elements and rebuilding them

Simply adding more structural material so that the original strength is more or less restored.

The process may involve inserting temporary supports, underpinning, etc.

Strengthening is an improvement over the original strength when the evaluation of the building indicates that the strength available before the damage was insufficient and repair alone will not be adequate in future damages.

Damages & Repair Methods1) HOUSE LEVELING

When house is built on soil that doesn’t have good load-bearing characteristics.

Weak soil is likely to compress or settle when a major load is imposed, which explains why some houses sink and/or tilt over time.

SOLUTION

Piering and Underpinning techniques to connect the foundation with stable soil at greater depths. Then the house can be lifted back to its original level orientation.

Small, quiet and vibration free hydraulic equipment is used to install the steel push piers, also known as resistance piers.

Piers are designed to drive deeply through soils and bear on rock or other load bearing material.

As soils shrink, from the summer heat, steel piers will support the homes foundation keeping the structure stable and crack free.

PIERING

UnderpinningMASS CONCRETE UNDERPINNING

This underpinning method strengthens an existing structure's foundation by digging boxes by hand underneath and sequentially pouring concrete in a strategic order.

The final result is basically a foundation built underneath the existing foundation. 

This underpinning method is generally applied when the existing foundation is at a shallow depth, however, the method still works very well even at fifty feet deep

UnderpinningBEAM AND BASE UNDERPINNING

A reinforced concrete beam is constructed below, above or in replacement of the existing footing.

The beam then transfers the load of the building to mass concrete bases, which are constructed at designed strategic locations.

UnderpinningBEAM AND BASE UNDERPINNING

A reinforced concrete beam is constructed below, above or in replacement of the existing footing.

The beam then transfers the load of the building to mass concrete bases, which are constructed at designed strategic locations.

2) BULGED FOUNDATION WALLS

If our measurements anywhere between the floor and

the top of the wall is greater than the distance measured

(wall to string) at the floor bottom and at the wall top then

the wall is "bulged" inwards at that point.

SOLUTION

Pilasters may be constructed against the existing foundation wall(s) to add stability and resist further movement.

Steel I-beams or U-channel beams may be placed

Foundation Anchors may be used to stabilize a foundation wall

Exterior Reinforcing Sister Walls for Repair of Foundation Wall Bulge

Pilasters A pilaster is a masonry column or short wall which is constructed

butting against the original wall at right angles.

Steel I Beams or U Channel Steel I-beams or U-channel beams may be placed against the bulged wall,

anchored at their bottom to the floor slab and at their top to building floor framing.

The beam is placed with its side against the most-inward-protruding portion of the wall.

The bottom of the vertical I-beam is secured by breaking a hole into the concrete floor slab where the bottom of the I-beam is cemented in place

Foundation Anchors Foundation Anchors may be used to stabilize a foundation wall which is

not badly damaged. This approach uses horizontal driven pins to anchor the wall to the surrounding soil and resist further movement

Reinforcing Sister Walls(Interior or Exterior)

An inside or outside foundation-reinforcing wall may be constructed against the bulged foundation wall.

Unless the outside cause of bulging (such as water or frost) is also corrected, the durability of this approach is doubtful.

3) VERTICAL FOUNDATION MOVEMENT

SOLUTION

The cracks and foundation movement are probably due to a combination of:

poorly prepared foundation footings,

blasting on an adjacent building

possibly omission of steel reinforcement in the poured wall.

Mud Jacking Method( Pressure Grouting)

Polymer Injection

Mud Jacking or Grout Pumping Grout pumping or mud jacking is injecting a Portland cement and sandy loam

mixture through a 2 inch hole under pressure through the slab to lift the foundation.

Used to stabilize soils below settling footings or slabs.

This method of foundation repair is capable of lifting a slab and possibly some structures.

Mud jacking is suitable if bearing rock or stable soils are not too deep. 

Polymer InjectionAs an alternative to mud jacking, it’s possible to inject a special type of expanding foam beneath settled concrete, utilizing the foam’s expansive qualities not only to raise the concrete but also to strengthen the soil.

Thank You