Types of foundation repair
Before start on with types of foundation repair, any one may have the doubt, how to identify the foundation problems?
For them, following are some of the reasons which may help to find the issues in foundation.
Bumpy or descending floor which cause the floor to separate from its floor, cracks in the bricks or blocks of a wall, cracks in the ceiling decorations/ mouldings, swelling exposure of a part of wall or noticeable split or separation in a continuous wall, overlapping of cracked wall parts (commonly this crack can be seen on wall between the door frame and ceiling), cracks in steps / floor / floor tiles, can’t open or close the door / window properly and separation between door/ window frame & wall.
Now let’s consider what reasons may cause foundation distress?
Contents of the soil, compression or expansion in soil, improperly compacted soil, natural disasters like earth quake, sudden exertion of artificial forces or poor maintenance can led the foundation structure to repair. Uneven movement among the soil layer after the settlement of foundation structure causes the damages as, the foundation structure rests on soil layer.
Now let’s land on the main part of the article that is types of foundation repairs.
Sealants in foundation repair
The simple or minor cracks can be treated with masonry patches or sealants but a regular maintenance is encouraged. Hydraulic cement ( – similar to cement mortar and sets very fast with respective to time) or epoxy (- similar to paste and available in a variety of viscosity as to use various width of cracks) or polyurethane (- a good sealer and fast setting) are some of the sealers used in construction industry nowadays for minor cracks. Chipping the crack and doing masonry patches using sealers is only favorable with minor cracks.
Slab jacking or mud jacking in foundation repair
In early days, the sunken slab raised by filling mud under the slab or filling concrete mixture under the slab using hydraulic pumps. But now-a-days the hydraulic pump was replaced by a trailer which consists of polyurethane system. A trailer which can carry needed amount of cube, portable hydraulic slab-raising pump, concrete mixer and time duration for the cleaning process of the machine can be eliminated in the new process as it never needs heavy equipment such as concrete mixer and less time to clean the equipment (the equipment is just the injecting gun..!).
In the slab jacking process by concrete mixture or mud mixture, the mixture spooned into a concrete mixer to add the water and additives. Then the final mixture is shifted to the portable pump and then the pump can moved to the necessary location. Finally the mixture can be pumped into the drilled holes using hoses. When the pump is empty it should be refilled with the mixture. But in slab jacking process by polyurethane, many steps which I previously mentioned can be eliminated. Here, only the process of injecting the foam into the holes is needed. In the trailer the two liquids which can react to get the desired foam are stored separately. After the holes are drilled, the injecting gun which one end is attached to the hose is inserted into a hole to pump out the foam. Within short period of time the foam expands its volume by nearly 25 times and sets to a rigid material. That’s simple is it? But this, polyurethane foam slab jacking is little more expensive when compare to mud or concrete slab jacking.
Slab jacking is a common process to regain the position of sunken concrete by pumping cement mixture & other additives. Slab jacking is not a simple task as it needs professionally specialized equipment, knowledge and persons. Using portable equipment such as pump & hoses the cement mixture will pump into the tactically drilled holes on the existing concrete structure.
Advantages of slab jacking
The new concrete mixture act as a strengthen base for the old one. When comparing to replace the whole structure, the cost of slab jacking is low. The place where slab jacking has been done can be used within hours. No wastage and sound pollution when compare to replacement of a new structure. This method is suitable for any weather condition. Doesn’t need to clean the place as this method never mess up the place when compare to the rest. No colour change in the structure as the new concrete mixture spreads beneath the old slab layer.
But there are some problems while handling the process, such as, excessively pumped concrete mixture or thin concrete mixture may lift the structure on a wrong place or tends to form new cracks or enlarges the old cracks.
Piering or Piling in foundation repair
The piering or technique of piling can be guessed from its name. Yes, steel or concrete piers used to resettle the foundation. But there is a slight difference between piering and piling technique. Piering can be done by excavation while piling can be done by driven piles into the ground. Concrete pressed piling, steel pressed piling and bell bottom piering are some varieties in use.
Steel pressed piling
In this type there are two ways such as Piling piers and Piering helical piers. Piling piers is galvanized or coated steel pipes are driven into the ground with the help of hydraulic ram and piering helical piers is galvanized or coated screw piles with steel shafts are used to here. To install this, a trench should be dug around the foundation and when the steel pile reached a suitable stable point, the hydraulic jack is used for bring the foundation back to its normal position. Finally the steel shaft attached to the pile is fixed to the foundation by bolting or welding.
Advantages of steel pressed piling
The steel piers can press deeply into the soil and give a firm attachment to the soil. Also the installation cost of steel piers is low. Steel piers can withstand for heavy weights when compare to concrete piers.
Concrete pressed piling
Drill holes on the structure which is in need of repair to a deep depth. Then fill the hole with reinforcement and concrete. Sometimes precast concrete piles are used, which never use any reinforcement. (It’s not a long tern help-full repair system).
Advantages of concrete pressed piling
The cost is low, no heavy equipment needed, not much tactical as the slab jacking method.
Whenever the concrete piles are pressed into the soil, the chance of getting misaligned is more and they get damaged with the increase of force you applied to press them into the soil.
Bell bottom piers
Here a shaft in the shape of bell drilled in to the foundation structure and then the space after the belled shaft is removed will fill with reinforcement and concrete.
Advantages of bell bottom piers
Give good strength as it is reinforced, the shape of the bottom prevent the piers from unwanted movements within soil layer.
The piers have to be cured well before the completion of project and takes more time when compare to the rest.
Soil Modification in foundation repair methods
Soil modification or soil stabilizing is the process to make the soil stiffer and stable than the previous. Here, voids within the soil layers are filled by some chemicals. The process is somewhat likely to the slab jacking. Many users hardly recommend this method as it needs more knowledge and well trained guide. Also the cost and maintenance is high.
Advantages of soil modification
Soil modification method is fast response, long lasting, less damage to the structure and also environmental friendly method.