Preventing Wood Decay

With the warm days of summer coming to an end and autumn beautifying our surroundings with oranges and yellows, now is an excellent time to start thinking of how to protect your deck/veranda from decay next year caused by rot and insect infestation. Understanding what causes wood to decay will help you choose the method of protection that is right for your home.

 

 

 

Natural Processes

 

 

Wood is a natural, organic substance with a distinct life cycle involving seeding, growth, death and decomposition. We have discovered that wood is an economical material to build with. We have developed methods to keep wood from decomposing once a tree has been felled and sectioned for log homes, decks, porches, or verandas.

 

Weathering, insect infestation and fungal attacks are all natural processes that significantly affect wood's life. However, fungal attack, or rot, leads to more rapid decomposition of the wood and causes more significant structural problems in North America than weathering or insect infestation.

 

 

 

Weathering

 

The effects of the sun's ultraviolet rays, rain, wind and freeze/thaw lead to a decomposition of the wood structure on the surface called weathering. This often leads to a greying or browning of the surface of the wood to a depth of about 1/100" deep.

 

 

Insect Infestation

 

Insects use the wood in the logs for food, lodging and breeding. This may lead to decomposition of the wood or decomposition of your level of satisfaction with the home.

 

 

Fungus

 

Fungus attack can lead to the structural decomposition of your wood elements of your home. Where does fungus come from? Fungus is in the particular plant family which does not produce their own food by photosynthesis as green plants containing chlorophyll do.

 

Fungi comes in various rot-producing forms, none of which any of us want in our wood. These fungi are all around us – in the forest before the tree is felled and at the sawmills where the trees are made into logs or boards. Understanding how fungi attach to the wood is half the battle in protecting our homes.

 

 

Elements Necessary for Fungal Growth

 

Four basic elements must be present for the fungus spores (seed for fungus plants) to grow and reproduce. These are food sources (wood), water, oxygen and proper temperature.

 

 

 

Wood

 

Some species contain natural chemicals (extractives, tannins or resins), that act to resist fungal attack. However, over time and given satisfactory conditions, even the more resistant species of wood will succumb to fungal attack. The natural chemicals disperse and fungus attacks the wood structure feeding on the cellulose and lignin fibers that make up the structure of the wood.

 

 

 

Water

Fungus require moisture (water) in close proximity to the wood fiber to grow. The moisture content by weight in wood at which fungus begins to thrive is 20-22% and ideal conditions exist at 26-32%.

 

 

 

Oxygen

In addition to water, oxygen must be present to provide for fungal growth. Generally, it is agreed that 20% air volume in the wood is required to provide enough oxygen for the fungus to process the wood into food.

 

 

 

Temperature

 

The ideal temperature for fungus to thrive is 75-90˚ F. A more comprehensive range of 40-105˚ F will sustain fungal growth.

 

If you remove one or more of these necessary elements, the fungus cannot develop, and rot is prevented. For example, wood has not decomposed after centuries locked up in an Egyptian tomb where water is not in proper amounts. Furthermore, logs remain solid and intact underwater, where oxygen does not exist in necessary quantities.

 

Therefore, it is essential to minimize the opportunities for our log home to be exposed to these four elements. Of these, water is perhaps the easiest element to control. There are many ways we deal with water content in our logs.

 

 

 

Moisture Content Control

If you are in the planning stages of your log home, there are things to be done to reduce the potential of increasing moisture content in the wood of your home. Following are some home design provisions you may want to incorporate.

 

Eave overhang minimum 24" at the base to 36" at the peak (ideally 48" at the peak)

Flashings over windows and doors and projections from walls

Properly installed eavestroughing

Adequate attic ventilation to prevent moisture buildup in the wall/attic interfaces

Adequate grade clearance or splash height (19" min), ideally with a first course flashing (see Figure 2), keeping ground moisture away from the log.

Also, there are some points to consider in terms of where you choose to build your home. The location should be on dry ground, have access to air movement, and be orientated to allow sun exposure.

 

The design of log joinery in your home is also essential. Try to include the following items in your home:

 

Logs incorporating a drip edge to provide for shelf water runoff

Boxed in heart logs that dry in an oval shape providing a slope for continual runoff of shelf water that moves into the space between logs and comes to rest on flat spots of logs like at corners

Fill all countersunk spike head holes with caulking as construction takes place.

NOTE:  Heartwood generally contains the largest concentration of extractives which aid in preventing the attack from fungus. Thus, removing sapwood from logs or wood can improve decay resistance.

 

Some species, such as northern white cedar, contain inherent heart rot (found in naturally growing trees), which can counteract the positive feature of the extractive. It is necessary to screen out all logs containing this fungus.

 

Further, logs cut in the winter or fall are less likely to have fungus spores attached because the low temperatures prevent spore development, movement and deposit on the records. Logs at the mill and on your property should be stacked apart and stored in well-ventilated, covered sites off the ground.

 

Wood which is placed in open areas free from direct contact with moisture (resting off the ground and protected at least partially from rain) will dry out to an equilibrium moisture content of 15-19%. This moisture content is lower than the wood moisture content of 20% or greater. This depends somewhat upon the location. For example, wood would be drier stored in a desert than by the ocean.

 

Thus, wood will not decay from fungus attack unless extra moisture is in contact with the logs for more extended periods, causing a higher moisture content in the wood. An example of this situation would be a window header improperly flashing, allowing rainwater to collect and lay for long periods.

 

If your log home is already constructed and you are trying to decide what finishes you might apply, consider the following. Paints, stains and varnishes do not prevent rot if the elements necessary to sustain fungal growth are present.

 

Paints and coatings were first used to prevent weathering, not rotting. They acted as UV blockers preventing the decomposition of lignin by the ultraviolet rays from the sun. Additives that resisted fungal attacks were introduced, such as copper naphthenate and additives like paraffin wax, which prevents or retards moisture migration.

 

 

 

Use of Coatings

A log home, deck, veranda, or porch should never be painted since paint places a coating on the log, preventing the log from absorbing and releasing moisture. Moisture will become trapped, leading to contents higher than 20% in the wood. This will result in decay.

 

A coating is defined as any material with a percentage of solids higher than 36-38%. Stains usually have 25-30% solids. A stain contains water or petroleum-based product known as the carrier, which moves the pigments (solids) into the cellular structure on the surface of the wood and deposits the pigment against the cell wall. These pigments are usually darker and absorb the ultraviolet rays before they get to the wood structure, thereby protecting the wood from weathering.

 

 

Use of Stains

 

Stains allow the wood's pores to remain open, providing free travel of moisture, which is desired. Thus, stains are preferable for log homes.

 

Additives which resist insect attack can be added to the stain for extra protection. Additives can also be used to retard (not stop) moisture flow allowing logs to dry more evenly and reduce checking and surface cracks.

 

This still allows the wood to transfer moisture in and out through the surface and is acceptable. Repellents that totally block moisture flow are not advisable to put on a log home.

 

When staining a log home or other wooden structures, it is also important to note that if the structure(s) that have just been constructed with green logs needs 2-4 months, the surface can dry to a depth of about 1/4". This will prevent water, migrating from the inside of the log, from mixing with the stain causing drip marks, flaking, peeling blotches and white powder (standard in pine).

 

Commercial methods impregnate the log under vacuum pressure with chemicals like chromated copper arsenate. These processes generally only impregnate the sapwood and are incapable of fair heartwood treatment. Since they can only be impregnated this way at the plant, re-machining the log on the site will expose untreated wood.

 

Recently a method of dipping the green logs (logs that have a moisture content over 26-30%) at the plant in a liquid containing a borate has been becoming popular. This is commonly called a diffuse wood treatment. The borate in the liquid diffuses into the log and onto the cell wall. This then acts as a repellent to insects and fungus. Since sapwood exhibits less favourable shrinkage characteristics and the chemical toxicity is questionable, some people find this technique unacceptable.

 

However, care should be exercised in generalizing the effectiveness of this technique. Little independent research has been carried out, and neither information nor regulatory standards for control of key variables during the processing have been established, variables such as the temperature of wood, species of wood and the time of immersion.

 

However, if performed correctly, the process has a promising future for log home protection and maintenance.

 

 

 

Conclusion

In summary, the best approach to preventing decay in your home or outdoor area is to remove the opportunities for moisture buildup at various points in the wood.

 

Stains are used to prevent weathering and, with additives, can repel insects and fungus, but they won't prevent rot if suitable conditions exist. Measures must be taken to ensure that you know how to deal with the sources of food (wood, water, oxygen and temperature) on which fungus thrives on.

 

A proper balance of design, manufacture and log surface protection will protect your log home and provide low maintenance for years to come.

 

 Thanks https://woodrandd.com/

 

The Bhand Deval Jain temple is built in the north of the eleventh century. The temple is in the Mahakoshal area of Arang. The temple is built in Bhumija architecture. The bottom of this temple has detailed ornaments. It has a sole that supports a pedestal on the wall and two rows of statues. The temple layout plan is a star-shaped one known as the stalette. The temple grows up to five floors, considered an unusual feature. The temple's face is on the west side. The temple is in harsh condition. In the past, a pavilion and a porch probably existed as part of the temple. The damaged front of the temple tower has been plastered without any decoration and also white. The northeast and southeast faces of the Temple Tower, all that were diluted, have been repainted in brick and mortar, but seriously. However, the overall view of the tower is still pleasant. Once upon a time, this temple was used as a survey marking station. As there was a tendency for the upper half of the tower to structurally explode by its borders, a metal strap bracing has been wounded around the tower in the middle section to give it stability. The top of the tower has a similar strap wound round. A large number of paintings have been engraved on the exterior and interior faces of the temple. The bigger images are engraved in two lines. Above the lines of bigger images, a line of carving small images is drawn. Inscription panels, flowers, and a line of highly decorated depictions of a royal march of horses, animals and people based on large images. The exterior faces of the temple are decorated with carved paintings.

Thanks, Indian Contents

Bacteria based self healing concrete

For every person on earth, more than 1 m³ of concrete is produced every year. This hunger for concrete has far-reaching consequences, as typically 100 kg of CO₂ is emitted into the atmosphere for the production of one ton of concrete. This is mainly caused by the use of cement which constitutes concrete, together with water, aggregate (gravel, sand) and possibly steel reinforcement bars. This is not a bad figure compared to other common construction materials, such as masonry, steel or aluminum. Moreover, concrete, during its life, slowly absorbs CO₂ in the process of carbonation, by which Ca(OH)₂ in the concrete is converted into CaCO₃. Nevertheless, the amount of concrete that is produced still makes it a significant source of anthropogenic CO₂ emissions.

It is therefore no surprise that several strategies have been devised to make concrete more sustainable. The most straightforward method is to (partially) replace cement by greener alternatives, such as blast furnace slag or fly ash, which are by-products of the iron and coal industries, respectively. Another complementary solution is to increase the lifetime of concrete, thus reducing the need for replacement materials. Currently, this is achieved by inspecting and repairing the structure periodically, but this is expensive and time-consuming. Moreover, degradation of concrete usually begins with microcracks that are hardly visible to the naked eye, if at all. 

Figure 1

Now a day, biologically modifications of construction materials become more popular for strength improvement and long-term sustainability. An investigation has been conducted to study the compressive strength of concrete by using two different bacteria named Bacillus Cereus and Bacillus Subtilis with three different concentration (viz. 10³, 10⁵, 10⁷ cells/ml) of each bacterium. It has been found that there was an increase in compressive strength at both 7 days and 28 days. It was noticed that the optimum concentration was different for different bacteria. The optimum concentration of Bacillus Subtilis and Bacillus Cereus were found as 10⁵ cells/ml and 10³ cells/ml respectively. Moreover, more compressive strength was obtained by addition of Bacillus Subtilis at optimum concentration compared to the samples made with all three concentrations of Bacillus Cereus both at 7 and 28 days.

Cracks in concrete are inevitable and are one of the inherent weaknesses of concrete. Water and other salts seep through these cracks, corrosion initiates, and thus reduces the life of concrete. So there was a need to develop an inherent biomaterial, a self-repairing material which can remediate the cracks and fissures in concrete. Bacterial concrete is a material, which can successfully remediate cracks in concrete.

This technique is highly desirable because the mineral precipitation induced as a result of microbial activities is pollution free and natural. As the cell wall of bacteria is anionic, metal accumulation (calcite) on the surface of the wall is substantial, thus the entire cell becomes crystalline and they eventually plug the pores and cracks in concrete. This paper discusses the plugging of artificially cracked cement mortar using Bacillus Pasteurii and Sporosarcina bacteria combined with sand as a filling material in artificially made cuts in cement mortar which was cured in urea and CaCl₂ medium.

 https://www.spiedigitallibrary.org/conference-proceedings-of-spie/4234/0000/Bacterial-concrete/10.1117/12.424404.short

https://www.sciencedirect.com/science/article/abs/pii/S0950061817313752

https://www.sciencedirect.com/science/article/pii/S1369702111701936

Ground Improvement Techniques

Purpose of ground improvement

Ground-improvement methods are those that are capable of improving certain characteristics (e.g. increase in bearing capacity, reduction in total as well as differential settlement, reduction in permeability, slope stability, prevention of soil erosion caused by piping and seepage, reduction of uplift pressure, decrease in liquefaction potential of soil, reduction of swelling and cracking of soils, identification of suitability of site to facilitate construction works, etc.) of poor ground for civil engineering constructions and various infrastructure developments. So a ground improvement method or technique is required to alter the state, nature, or mass behaviour of ground materials in a controlled manner in order to achieve an expected and satisfactory response to existing or projected environmental and engineering actions.

There are alternate options to ground improvement as well. These are

a.

to remove and replace the soil mass with another type of soils or other geomaterials of suitable quality for the construction work

b.

to bypass the poor soil with the help of a suitable technique like pile foundation

c.

to alter the design (height and configuration) of structures to overcome the ground limitations

d.

to change the construction site and look for a new one.

However, due to the scarcity of land in present conditions, heavy loading structures, competitive design, the need for speedy construction, and various political and economic issues, a ground-improvement technique may be the only feasible option for civil engineering constructions. 

The selection of ground-improvement techniques depends upon various factors like the cost and time available to complete the project, reasons for improving the ground, extent and depth of ground to be treated, geotechnical properties of the existing in situ soils/rocks, accessibility to the project site, availability of materials, equipments and manpower required to improve the ground, environmental factors, local experience, and preference of contractors and engineers.

The ground can be improved by adapting certain ground improvement techniques. Vibro-compaction increases the density of the soil by using powerful depth vibrators. Vacuum consolidation is used for improving soft soils by using a vacuum pump.

Preloading method is used to remove pore water over time. Heating is used to form a crystalline or glass product by electric current. Ground freezing converts pore water to ice to increase their combined strength and make them impervious. Vibro-replacement stone columns improve the bearing capacity of soil whereas Vibro displacement method displaces the soil. Electro osmosis makes water flow through fine-grained soils.

Electrokinetic stabilization is the application of electro-osmosis. Reinforced soil steel is used for retaining structures, sloping walls, dams etc. seismic loading is suited for construction in seismically active regions. Mechanically stabilized earth structures create a reinforced soil mass.

The geo methods like Geosynthetics, Geogrid etc. are discussed. Soil nailing increases the shear strength of the in-situ soil and restrains its displacement. Micropile gives the structural support and used for repair/replacement of existing foundations.

Grouting is the injection of pumpable materials to increase its rigidity. The jet grouting is quite advanced in speed as well as techniques when compared with the general grouting.

Rapid urban and industrial growth demands more land for further development. In order to meet this demand land reclamation and utilization of unsuitable and environmentally affected lands have been taken up. These, hitherto useless lands for construction have been converted to be useful ones by adopting one or more ground improvement techniques. The field of ground improvement techniques has been recognized as an important and rapidly expanding one.

Latest Ground Improvement Techniques

Following are the recent methods of ground improvement Techniques used for stabilization of soil:

• Vibro Compaction
• Vacuum Consolidation
• Preloading of soil
• Soil stabilization by heating or vitrification
• Ground freezing
• Vibro-replacement stone columns
• Mechanically stabilized earth structures
• Soil nailing
• Micro-piles
• Grouting

Vibro-Compaction Method of Ground Improvement

Vibro-compaction sometimes referred to as Vibroflotation, is the rearrangement of soil particles into a denser configuration by the use of powerful depth vibration. Vibro Compaction is a ground improvement process for densifying loose sands to create stable foundation soils.

The principle behind Vibro compaction is simple. The combined action of vibration and water saturation by jetting rearranges loose sand grains into a more compact state.  Vibro Compaction is performed with specially-designed vibrating probes. Both horizontal and vertical modes of vibration have been used in the past.

The vibrators used by Terra Systems consist of torpedo-shaped probes 12 to 16 inches in diameter which vibrates at frequencies typically in the range of 30 to 50 Hz. The probe is first inserted into the ground by both jetting and vibration. After the probe reaches the required depth of compaction, granular material, usually sand, is added from the ground surface to fill the void space created by the vibrator. A compacted radial zone of granular material is created

Advantages of Vibro Compaction Method:

• Reduction of foundation settlements.
• Reduction of risk of liquefaction due to seismic activity.
• Permit construction on granular fills.

Vacuum Consolidation of Soil for Ground Improvement

Vacuum Consolidation is an effective means for improvement of saturated soft soils. The soil site is covered with an airtight membrane and vacuum is created underneath it by using dual venture and vacuum pump. The technology can provide an equivalent pre-loading of about 4.5m high conventional surcharge fill. Vacuum-assisted consolidation preloads the soil by reducing the pore pressure while maintaining constant total stress.

Applications of Vacuum Consolidation of Soil:

• Replace standard preloading techniques eliminating the risk of failure.
• Combine with a water preloading in the scare fill area. The method is used to build large developments on thick compressible soil.
• Combine with embankment pre-load using the increased stability

Preloading or Pre-Compression of Soil for Ground Improvement

Preloading has been used for many years without a change in the method or application to improve soil properties. Preloading or pre-compression is the process of placing additional vertical stress on a compressible soil to remove pore water over time. The pore water dissipation reduces the total volume causing settlement. Surcharging is an economical method for ground improvement. However, the consolidation of the soils is time-dependent, delaying construction projects making it a non-feasible alternative.

The soils treated are Organic silt, Varved silts and clays, soft clay, Dredged material The design considerations which should be made are bearing capacity, Slope stability, Degree of consolidation.

Applications of Preloading of Soil

• Reduce post-construction
• Settlement
• Reduce secondary compression.
• Densification
• Improve bearing capacity

Thermal Stabilization of Soil for Ground Improvement

Heating or vitrification breaks the soil particle down to form a crystalline or glass product. It uses electrical current to heat the soil and modify the physical characteristics of the soil. Heating soils permanently alters the properties of the soil. Depending on the soil, temperatures can range between 300 and 1000 degree Celsius. The impact on adjacent structures and utilities should be considered when heating is used. .

Applications of Vitrification of Soil:

• Immobilization of radioactive or contaminated soil
• Densification and stabilization

Ground Freezing Technique for Ground Improvement

Ground freezing is the use of refrigeration to convert in-situ pore water to ice. The ice then acts as cement or glue, bonding together adjacent particles of soil or blocks of rock to increase their combined strength and make them impervious. The ground freezing considerations are Thermal analysis, Refrigeration system geometry, Thermal properties of soil and rock, freezing rates, Energy requirements, Coolant/ refrigerant distribution system analysis.

Applications of Ground Freezing Technique

• Temporary underpinning
• Temporary support for an excavation
• Prevention of groundwater flow into the excavated area
• Temporary slope stabilization
• Temporary containment of toxic/hazardous waste contamination

Vibro-Replacement Stone Columns for Ground Improvement

Vibro-Replacement extends the range of soils that can be improved by vibratory techniques to include cohesive soils. Reinforcement of the soil with compacted granular columns or “stone columns” is accomplished by the top-feed method. The important Vibro-replacement stone columns are Ground conditions, Relative density, Degree of saturation, Permeation.

Principles of Vibro-Replacement Technique

The stone columns and intervening soil form an integrated foundation support system having low compressibility and improved load-bearing capacity. In cohesive soils, excess pore water pressure is readily dissipated by the stone columns and for this reason, reduced settlements occur at a faster rate than is normally the case with cohesive soils.

There are different types of installation methods which can be broadly classified in the following manner:

• Wet top feed method
• Dry bottom feed method
• Offshore bottom feed method

Summary of Vibro Replacement Method

Principle	Reinforcement Drainage
Applicable soil(s)	Mixed deposits of clay, silt and sand Soft and ultra-soft silts (slimes) Soft and ultra-soft clays Garbage fills
Effect(s)	Increased shear strength Increased stiffness Reduced liquefaction potential
Common applications	Airport taxiways and runways Chemical plants Storage tanks & silos Pipelines Bridge abutments and approaches Offshore bridge abutments Road and railway embankments
Maximum depth	20-40 m
Land / offshore application	Both

Applications of Vibro-Replacement for Ground Improvement:

• Reduction of foundation settlement
• Improve bearing capacity/reduce footing size requirements
• Reduction of the risk of liquefaction due to seismic activity
• Slope stabilization
• Permit construction on fills
• Permit shallow footing construction

Ground Type	Relative Effectiveness
Sands	Excellent
Silty sands	Excellent
Silts	Good
Clays	Marginal to good
Minespoils	Excellent (depending on gradation)
Dumped fill	Good
Garbage	Not applicable

Mechanically Stabilized Earth Structures

A segmental, precast facing mechanically stabilized earth wall employs metallic (strip or bar mat) or geosynthetic (geogrid or geotextile) reinforcement that is connected to precast concrete or prefabricated metal facing panel to create a reinforced soil mass.

Principles of Mechanically Stabilized Earth Structures:

• The reinforcement is placed in horizontal layers between successive layers of granular soil backfill. Each layer of backfill consists of one or more compacted lifts.
• Free-Draining, non-plastic backfill soil is required to ensure the adequate performance of the wall system.
• For walls reinforced with metallic strips, the load is transferred from the backfill soil to the strip reinforcement by shear along with the interface.
• For walls with ribbed strips, bar mats, or grid reinforcement, the load is similarly transferred but an additional component of strength is obtained through the passive resistance on the transverse members of the reinforcement.
• Facing panels are typically square, rectangular, hexagonal or cruciform in shape and are up to 4.5m ^2 in area.
• MSEW- Mechanically Stabilized Earth Walls, when the face batter is generally steeper than 70 degrees.
• RSS- Reinforced Soil Slopes, when the face batter is shallower.

Applications of Mechanically Stabilized Earth Structures:

• RSS structures are cost-effective alternatives for new construction where the cost of embankment fill, right-of-way, and other consideration may make a steeper slope desirable.
• Another use of reinforcement in engineered slopes is to improve compaction at the edges of a slope to decrease the tendency for surface sloughing.

Design:

Current practice consists of determining the geometric reinforcement to prevent internal and external failure using limit equilibrium of analysis.

Soil Nailing Technique for Ground Improvement

The fundamental concept of soil nailing consists of reinforcing the ground by passive inclusions, closely spaced, to create in-situ soil and restrain its displacements. The basic design consists of transferring the resisting tensile forces generated in the inclusions into the ground through the friction mobilized at the interfaces.

Applications of Soil Nailing Technique:

• Stabilization of railroad and highway cut slopes
• Excavation retaining structures in urban areas for high-rise building and underground facilities
• Tunnel portals in steep and unstable stratified slopes
• Construction and retrofitting of bridge abutments with complex boundaries involving wall support under piled foundations

Micropiles for Ground Improvement

Micropiles are small diameter piles (up to 300 mm), with the capability of sustaining high loads (compressive loads of over 5000 KN). The drilling equipment and methods allow micropiles to be drilled through virtually every ground conditions, natural and artificial, with minimal vibration, disturbances and noise, at any angle below horizontal. The equipment can be further adapted to operate in locations with low headroom and severely restricted access.

Applications of Micropiles for Ground Improvement

• For Structural Support and stability
• Foundation for new structures
• Repair / Replacement of existing foundations
• Arresting / Prevention of movement
• Embankment, slope and landslide stabilization
• Soil strengthening and protection

Example of Micro Piles for Ground Improvement:

In India, in some circumstances steel pipes, coated wooden piles are used as cost-effective Options in improving the bearing capacity of foundation or restrict Displacements to tolerable levels and similar uses in the stabilization of slopes, strengthening of foundations are common.

Sridharan and Murthy (1993) described a Case study in which a ten-storeyed building, originally in a precarious condition due To differential settlement, was restored to safety using micropiles. Galvanized steel Pipes of 100 mm diameter and 10 m long with bottom end closed with shoe, driven at An angle of 60o with the horizontal were used and the friction between the pile and the soil was used as the design basis in evolving the remedial measures.

General Grouting for Ground Improvement

Grouting is the injection of pumpable materials into a soil or rock formation to change the physical characteristics of the formation. Grouting selection considerations are Site-specific requirement, Soil type, Soil profitability, Porosity. Grouting can be prevented by Collapse of granular soils, Settlement under adjacent foundations, Utility damage, Daylighting. Grouting can provide Increased soil strength and rigidity, reduced ground movement, Predictable degree of improvement.

Steps for General Grouting Technique for Soil Stabilization

• Identify underground construction problem.
• Establish objectives of grouting program.
• Perform special geotechnical study.
• Develop initial grouting program.
• Develop performance prediction.
• Compare with other solutions.
• Refine design and prepare specifications.

Grouting Techniques

The various injection grouting techniques used by grouting contractors for ground improvement/ground modification can be summarized as follows:

• Permeation
• Compaction Grouting
• Claquage
• Jet Grouting

Jet Grouting Technique for Ground Improvement

Jet grouting is a general term used by grouting contractors to describe various construction techniques used for ground modification or ground improvement. Grouting contractors use ultra high-pressure fluids or binders that are injected into the soils at high velocities. These binders break up the soil structure completely and mix the soil particles in-situ to create a homogeneous mass, which in turn solidifies.

This ground modification / ground improvement of the soil plays an important role in the fields of foundation stability, particularly in the treatment of load bearing soils under new and existing buildings; in the in-depth impermeabilization of water-bearing soils; in tunnel construction; and to mitigate the movement of impacted soils and groundwater.
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