Cement Grout Injection

Questions and Answers

Why do we go on providing water to the [dried] CEMENT of a recently built building or any such infrastructure?

Posted by Karishma
adminCement doesn’t dry… It hardens.
This hardening process is called hydration and continues for days long after the cement has firmed up enough to walk on.As hydration continues, the cement gets harder and harder until it reaches its full strenght in 28 days. During this curing the cement heats up from the chemical reactions and it also shrinks or contracts. In order for hydration to continue water must be present if enough water is not present then the hydration process will stop before the cement has had a chance to reach its full rated strenght.Newly poured cement is kept moist so that water is kept available for the hydration process to continue and most importantly to even the temperatures so the cement doesn’t crack. Evaporation is controlled by spraying with water or by covering the cement with materials or coatings which keeps the water from evaporating. During the curing (hydration) process heat is also generated, this heat can cause water to evaporate and halt the curing and cause the cement to crack due to uneven contraction. Neither condition is desirable so the cement is kept cool by spraying water on it.In some large cement pours cement is kept cool and wet by using ice and in some very large pours a cooling water system is cast in place (like what was done on the Hoover dam) After the cooling pipes are no longer needed they are filled with grout.

What’s Oxidation in building structures and how it weakens the strength of steel?My building needs major repairs due to cracks developed and sippage of rain & drain water through this crack. I want to understand the reasons for cracks and effect of water sippage on inner steel structure
in Concrete Beams, Columns and Slabs to begin Oxidation process.

Posted by Sunil S

adminRust is Ferrous Oxide, this is a compound of Iron and Oxygen. When air gets into the cracks, and makes contact with your steel, oxidation process starts. There is a misconception that water makes steel to rust. It is the oxygen in the air actually. However, water hastens the process of oxidation that’s why we suspect it to cause the rusting.The reason cracks on buildings are:1. Inadequate reinforcement. The bending moment of such elements might be too large that steel inside the element cannot withstand and causes the cracks on concrete.

2. Poor workmanship. During the concreting, there might be some honeycombs which were not treated effectively. The voids inside and outside the concrete weakens the concrete. This is also due to ineffective vibration during the placing of concrete.

3. Cold joints might not have been treated with grouting. Connection of concrete from old pour to new pour should have been treated with cement grout.

4. Lack of waterproofing. The materials which used for waterproofing of the structure is not effective enough to protect the concrete form water seepage

5. Creeping and Shrinkage of concrete. This characteristic of concrete takes long time to happen. Concrete shrinks and creeps with the changing temperature and humidity.

6. Design mix of concrete. Sometimes, during the placement of concrete, the strength of concrete being placed is not in accordance with design strength. Ex. Instead of pouring 5000psi, they pour 3500psi.

7. Others maybe less concrete cover, improper curing of concrete and additional loads might have been put to your structure which were not considered in the design.

I suggest that you check thoroughly whether the cracks you have identified are just hairline cracks or structural cracks for you to do the appropriate repair on your structure. Structural Epoxy injection is the commont method if you found structural cracks on you building.

Goodluck.

Masonry construction?What durability problems affect masonry structures and what can be done about them?Looking for a little helpany appreciated, thanks.

Posted by PHYYYSSSICCCS

adminMasonry construction is inherently durable since it is made of sand, cement, and water (among other things). It is an excellent building material if constructed by experienced masons and properly engineered to resist the loads to which the masonry will be subjected. Masonry may be reinforced or unreinforced. Over time, the mortar joints may need some maintenance to keep out rainwater. Water is the arch enemy of any masonry or concrete construction. Properly designed masonry construction includes reinforcing steel within the voids of the blocks and each cell in which the rebar is to be placed is to be grouted solid with a pea-gravel type of flowable concrete called mortar. Any masonry that supports earth such as retaining walls shall be grouted solid regardless of where the rebar is located. The mortar and grout ingredients and proportions are critical for long term masonry construction durability.If masonry cracks within the block, these cracks should be repaired using epoxy injection and then monitored for future movements.I am not sure of the the specific problem you may be experiencing with masonry.

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Questions and Answers

Which underground tube lines stop at Westminster?I need to get from London st pancras to westminster, does the northern line stop at westminster?

Posted by redbean

adminThe Jubilee, District and Circle lines stop at Westminster. The way to get there in the smallest number of stops is to take the Victoria line Southbound at King’s Cross St Pancras, from there it is 3 stops to Green Park, change there to the Jubilee line Southbound and Westminster is the next stop.

Just a point of interest – until just over 10 years ago the Jubilee line didn’t go past Charing Cross so Westminster station as it is now is a very recent construction. It’s quite a sight to behold as you come off the Jubilee line there… The whole station had to be rebuilt in connection with the construction of Portcullis House above it and basically what was done was to excavate a massive box under the building, lined with concrete and braced by steel poles, which you will see as you come up to the surface from the Jubilee line. The project had a very real risk of making Big Ben fall over (it’s just across the road) so care was taken to stop that by injections of concrete grout under Big Ben as the building works was going on. It won several architectural awards. I have to change trains there to get to work 5 days a week and I still find it impressive.

Tell me all you know about the leaning tower of pisa…ASAP?Ok tell me the history and what was cool there what you did there…..everything you know and did….it is for a school project due tomorrow!!! I am totally desperate!!!

Posted by charlie caparzo disalvatore

adminItalian TORRE PENDENTE DI PISA, medieval structure in Pisa, Italy, that is famous for the settling of its foundation, causing it to lean 17 feet from the perpendicular. The bell tower, begun in 1174 as the third and final structure of the city’s cathedral complex, was designed to stand 185 feet high and was constructed of white marble. Three of its eight stories were completed when the uneven settling of the building’s foundation in the soft ground became noticeable.

Bonnano Pisano, the engineer in charge, sought to compensate for the lean by making the new stories slightly taller on the short side, but the extra masonry caused the structure to sink still further. Work was suspended several times as engineers sought solutions, but the tower was ultimately topped out in the 14th century, still leaning.

In modern times the foundations have been strengthened by the injection of cement grouting, but in the late 20th century the structure was still in danger of collapse, and various schemes were being considered to save it.

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Questions and Answers

My House Walls are fully moist ,damp because of soil retained till slab what to do?Because of a gigantic structure(building) built behind my house which has only ground floor and slab,all walls are becoming fully damp.all switch boards such as tv,mixer, are all located on it what to do ???i m afraid that any kind of shocks will come what to do …any suggestions are appreciated ,thnq
a white thing is out frm these walls i want some remedies so as to avoid this and even be away from decreasing the strength of walls and even structures such slabs or footings or columns………im in dilemma plz help me out
Actually my adjacent property people(back side) have raised there plinth level upto our slab level thats the problem,water percolating frm soil nd entering my house walls..

Posted by Srujan
adminYour room’s wall are load bearing masonry wall & now it is also acting as retaining wall.If so you can talk to local authority to claim cost of strengthening of wall from your neighbour. This may be uphill task but it is your right.
You have to talk to structural designer with relevant data like hight & width of unsuported wall,wall thickness,water table,drainage system around both buildings.
Storm water system of neighbour’s building should also be checked so that if required water outlet location could be changed.
What you can do from your side of wall is to make injection grouting in wall backing at certain location with water proofing compound. It will also be better, if possible, to provide a drainage out let (weep hole) to release water accumulation from retaining side near the floor in wall.This outlet you can connect to your drainage system.If the water coming out from weep hole is not a clear water then you have to create a artificial filter on back of weep hole. For this you have to make one more hole at lower level below the first weep hole ,In this lower hole you have to fix a threaded nipple with blind(stopper).Mean while you make artificial filter in back of upper hole ,you can allow water temporary from this other hole.
Be remember that in any case you have to close weep hole if you are unable to stop flow of soil with water from weep hole.
Powdering on wall inform you that water is accumulating on back side of wall.
Designer may suggest to built additional pillars in wall from your side.Pillar & wall can be connected by steel connector & pocketing in existing wall.
Any water proofing on wall from your side face will be wasteful of money.

Why in injection grouting we utlized Grouting material likeGP1/2 instude of neat cement slurry?

Posted by Hamish Sharma

adminThis is an Engineering or Construction or Oil question, not Sculpture. Not sure why Y!A offered Sculpture up. Question also has several spelling errors (utilized, instead)

Q#1- Recently appears another fee in our EBMUD billing statement, which is called “Seismic Improvement Program

Posted by SHAD G
adminHi.
This statement meansClaremont Tunnel Seismic UpgradeThe 3.4-mile Claremont Tunnel, originally completed in 1929, is a major water supply artery delivering up to 175 million gallons per day of treated water from EBMUD’s Orinda Water Treatment Plant to more than 800,000 customers west of the Oakland-Berkeley Hills. The tunnel crosses the Hayward Fault about 130 feet below Tunnel Road in Berkeley and is very vulnerable to earthquake damage. Improving the tunnel’s earthquake performance is a cornerstone of EBMUD’s Seismic Improvement Program. If the tunnel were to fail after a major earthquake, the impacts would include:

Disruption of water delivery

Reduction in fire fighting capability

Severe water rationing for up to six months during tunnel repairs

Economic losses to the community estimated in 1994 at approximately $1.9 billion

EBMUD is seismically upgrading the tunnel so that it will survive a major earthquake and allow the safe delivery of water after such an event. Construction for the Claremont Tunnel Seismic Upgrade began in June 2004. The work includes:

A new 1,570-foot bypass tunnel to replace the most vulnerable portion of the Claremont Tunnel crossing the Hayward Fault

A 480-foot access tunnel and entry portal at EBMUD’s Claremont Center in Berkeley

Repairs and grout injection reinforcement for the remainder of the existing tunnel between Orinda and Berkeley

The inside of the bypass tunnel is lined with reinforced concrete.
All tunnel excavations and the concrete lining for the bypass tunnel have been completed. By Summer 2006, concrete lining, and the entry portal at the access tunnel will be completed. Repairs in the existing tunnel have also been completed, and during Winter 2006-07, grout injection for the existing tunnel, and the connections between the existing and bypass tunnels will be completed. In Spring 2007, earth fill to cover the access portal structure, and landscaping will be restored at the Claremont Center construction areas. All construction activity, including site clean-up and contractor demobilization, is anticipated to be completed by June 2007.

Available Publications

More information about the Seismic Improvement Program and the latest project newsletter to the community are available as PDF files below. They can be viewed and printed with Adobe Acrobat Reader, a free software.

Seismic Improvement Program Update (295KB)
Seismic Improvement Program 2005 Progress Report (3MB)

For more information or questions about the project please contact Project Liaison Donna Kerger at dkerger@ebmud.com or (510) 287- 0165.

 

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Questions and Answers

What will happen to the sinkhole in FL?

Posted by John
adminHttp://www.toadspad.net/safety/toad-sink…
I definitely would move I don’t trust them filling it in it could happen again
the foundation. Is this safe?A number of engineering companies routinely repair sinkholes. Techniques vary from simple injection of grout into the hole to more advanced systems of engineered reinforced plugs, pins, and porous concrete. In general, if a repair has been certified by a licensed engineer, and completed to the satisfaction of the homeowner’s insurance company, it is probably safe. However, as you are dealing with natural systems, there can be no guarantees that a repaired sinkhole will not cause future problems.

How costly is it to fix a moldy basement??I went and looked at a house this past weekend where i can get owner financing (only way i can finance right now) anyways i love it but there was water damage to the basement…the part thats finished with a fireplace. Other then that the house is perfect for us and the payments work. With the down payment they are asking i will have left over to not only repair the mold (my husband and father will do most of the work and know how to ) and put up a retaining wall to help make sure no more water damage in future.
Anyways i know they know ho wto fix it but do you know how much itd cost me to get it back to good shape?? I do not want to pass on this house but am just wondering how much/trouble itd be.
The upstairs is just over 1200 sq ft so id guess the moldy part of basement would be 600+sq ft.
Thanks so much and keep your fingers crossed for me.

Posted by Rachael

adminHmm….instead of turning away a golden opportunity..let me try to advise some ways perhaps to alleviate the basement water seepage problem.

Firstly, you must identify the sorce of water; it can be either at the basement wall & floor or the junction between them where the weakest point is. Ie. Mould will grow nearer to the water source – so don’t clean it first! Water seepage can also be identify by water marks, crystalization, dampness on wall, discolouration, etc. Bring a waterproofing contractor especially those who specialize in basement to examine the source and the extend of repair work & cost to determine whether it’s worthwhile and to get a second opinion.

Secondly, if the cost is acceptable & repair work is done ie by either expoxy grouting or injection into the wall/floor to seal-up cracks, pores, etc. You can embark on a long term rectification by waterproofing the entire wall/floor again. Ie applying another layer of waterproofing or do a cavity wall infront of the existing basement wall. The latter is prefered if there are too many seepage points in the walls and you can’t fix it all, you might as well drain them away. Hence, built a channel below (between the walls) and let the water drain out. With this method, your inner wall will be dry and free of mould.

Thirdly, water is food for mould. Hence, try to add more natural light & ventilation to basement to let it ‘breath’. Ie by opening up windows along the top wall if possible. If not, try to ventilate it by using exhaust fans ducted or along the windows.

Lastly, you can install dehumidifier or put some chemicals that absorb water ie salt, silicates, etc at the basement as added precautions.
Hope that this can assist you on whether you should buy the property….there are always solutions to a problem. Good luck & Cherrio…

Can you tell me the difference between grouting and injection?I dont know the difference below :
grouting machine and injection equipment ?
Grouting materials and injection materials?

Posted by yujun

adminInjection is placement of epoxy materials under extremely high pressure and is used to seal small width cracks in water retention structures.

Some grouting is not done under pressure typically. When grouting under column base plates, the grout may be placed by hand.

When grouting voids under slabs on grade, the grout is placed under some lower pressure to find and fill the voids and to prevent settlement.

The grout is usually cementitious in nature, i.e. Contains cements as part of its matrix. It may also contain sand and water. Some grouts are premixed, all you add it water and a means to paddle mix the mixture into a slurry mixture.

Epoxy injection is not cementitous, it is composed to usually a two part mixture of epoxy resin and other chemicals which are mixed on site and used quickly because the pot life (usable period during which the product may be used) is typically less than 30 minutes. Pot lif is ambient temperature dependent.

A good reference is sika products. Do a search at

www.sikausa.com.

What is Underpinning?

Underpin

Underpinning is the process of strengthening or stabilising foundations of an existing building.  There are several reasons why this may be necessary

  1. Original foundations of the building is simply not strong, stable enough.
  2. The supporting soil may have changed its bearing capacity.  For example water may have penetrated the area.
  3. New construction may require excavation close to the existing footings, thereby reducing their structural strength as a supporting agent.
  4. It is simply more economical to fix the existing then to build a new structure.  For example, the floor slab of the house may have sunk 50 mm.  Rather than rip it up and replace it.  One can just hydraulically raise by underpinning it with grout.

typical wall cracking

Diagrammatic video shows how Micro Piling one type of underpinning is achieved.

Above Typical stair crack from footing subsidence

Underpinning is achieved by strengthening the bearing capacity of the soil by injecting grout, or by increasing the area of the footing itself or putting a mass concrete footings or combination concrete, steel structures under the existing footing or Micro piling as shown in the previous video

 

Typical underpinning structure.

The following picture shows a basement being dug out to increase head height, so making the space user-friendly.  As the floor slab needs to be lowered  we have to underpin the existing footings of the surrounding walls.  In this case the underpinning was performed by laying bricks rather than mass concrete.  This is an example of point number four, “more economical”. In this case the underpin of footing depth varied between 200mm and 1200mm as original footing depth varied due to house being built on a slope. The previous DIYer’s had dug below grade of footings and had just concreted in front of them instead of doing the laborish job of underpinning. This no doubt accounts for some of the external wall cracks visible on this property.

exposing the existing footings of the basement

Basement is excavated to grade here and it is easy to see how far the existing footings are above the new level.  These walls need underpinning.

4 brick width underpinning for the double brick supported wall

You can see here partially build new brick foundation serving as underpinning for the existing 230mm brick wall. No concrete or piling was required here.

Excavating and underpinning existing sandstone common walls

Brick walls above supported with steel beams inserted, then the internal footings removed, subsequently excavated to level and then common property sandstone walls underpinned to rock.

Screw piles can be used before or after construction to provide solid foundation for new footings or underpinning. See samples in above video.

If your house is cracking up or you need to extend the basement, then you will need underpinning, you will need a specialist trades person.  This is not a do-it-yourself project as the risk is far too high of causing damage to your valuable asset.

References: Underpinning information: http://en.wikipedia.org/wiki/Underpinning

Trustworthy Builder:      http://all-builders.com.au

Confined Excavations:   http://bestexcavations.com.au

 

 house cracks    footing stabilization     wall cracks     my house is cracking       sinking house       slab sinking     basement excavation

Contact:      E-mail: info@bestunderpinning.com.au         Phone: 0411 212 211