Effects of Oil Spillage on Concrete

Dear all, to my immense relief, the customer agreed to have a civil engineer to check the "civil work" side of the problem.

I still would like to know your comments about the questions exposed, to help me estimate the timelines for different scenarios.

Salu2,

Abel.

With the given information, it is not clear how the problem can be taken care of.

Oil in concrete is not good to provide any binding adhesion to most of the classic repair materials as modified concrete mix where acrylic or other synthetic plasticisers are added. (also urethanes and/or epoxies)

To avoid this problem in the future, water resistant foundations should be provided.

As far as repair:

Instead of drilling with 10 mm bits, probably deep core drilling should be performed:

1. To examine the nature of the cracks

2. To get rid of as much oil saturated concrete as possible.

You also have a low chance of getting the oil out with water without modifying the oil e.g with ammonia (turns it into a kind of soap - beware and protect your lungs - with ammonia cartridge filters and adequate ventilation)

Firing out is also used, but can damage the concrete too.

All processes are worse than removing the soaked concrete and are also more time consuming actions.

After the "cleaning" tests can be done -

When you have drilled some "trenches", a new re bar reinforcement should be put in place in order to keep the block solidly together.

Connect with the reinforcement in place and pour the cavities with special concrete repair material.

Best of course is to "replace" the foundation by a new one. All the rest are repairs, and the current situation proves the job wasn't "well done" for the existing load.

Dear dvmdsc (DeVil Make Decision Study Civil?? ;)

That was a huge amount of useful info!

Quite helpful and, better even, in a language I understand (my background is mechanical, just meet, collide, fight for space or cranes... etc, with civil department at site).

For deep core drilling I understand the kind of cylindrical samples taken with hollow drills as in this pic. Is that correct?.

I have used them to demolish hard foundations and uproot heavy machines, reaching around 1200mm depth.(I am becoming kind of familiar with expansive cement lately!) It would for sure show the oil soaking degree and crack depth clearly.

I have requested the casting/rebar drawings of the foundation and the casting protocol where the the mixture and procedure used is detailed. The drawings to look for clearances in case we take samples, so no affect the key rebar works, and the protocol for the civil engineer (cements have funny names, that I do not understand) This should give us a general idea of the structure as well.

Chances are that the problem have the origin in the mechanical area, due to unbalanced load during operation (too bad can not put the fault on the E&I guys... yet).

I doubt the complete demolition would be necessary (nor acceptable for the client for that case). I have demolished two foundations of this machines, 40 and 20 years old each, and although oil was an habitual condition, never detected stains deeper than 30-50mm, at some spots only.

In any case my camera is ready with three spare batteries if it comes to that.

The cleaning procedure is clear, and security advice (good point) duly noted.

Salu2,

That is the type of drill indeed. Only the picture is not clear for me if the drill is spinning or the guy (around the drill). He uses his weight - also no water cooling is applied here.

It was only centering the machine position at that moment.

Here you have tracing drill points and drilling with water. The drilling machine is fixed with speedbolts for working.

As an extra, angle drilling position, to improve uproot effect when pouring expansive cement.

Thanks for the attention to the details!!

Cracks should be of significant concern simply because they don't go away, and can only get bigger...

One thing you can, and should, do immediately is to identify each visible crack with some kind of consistant numbering system (such as coordinates from the base of the equipment) , then spray-paint a dot on the end of each of the visible cracks, make an additional dark mark at the very end, and then photogragh (digitally, if possible) said crack-ends and record the date down on a weekly basis, to see and measure and record how quickly the cracks are (growing, if at all...).

Note also if the base of the equipment is slowly working it's way down into the concrete, even just a little bit...

Hopefully, the cracks in question are not growing, but eventually, even good concrete will start to deteriorate. The engineer will want to have some kind of preliminary indication of the general condition of the (progress) of the cracking, if he/she is not already on-site.

In any case, good luck, and tell us more when the results become available...

I don't know enough about concrete to suggest test methods or repair methods. I can suggest that whatever is done, patch repair or complete new floor, that before the machine is reinstalled, the concrete is sealed and painted as recommended by the concrete supplier. This will stop any liquid penetration in the future and help protect the integrity of the concrete.

I assuming that any rework will take the loading from the machine into account...

Good luck and thanks for a well set out question, covering all you knew.

Dear English Rose:

In our guidelines for machine foundation casting, your indications are boldly underlined, to wich I add fluorescent yellow highlighing.

Since the civil works are customer scope of supply, this is something that sometimes we get, sometimes not.

Maybe some helmet knocking should be contemplated as noticing option.

The project always have a heavy dosage of engineering in calculations of loads, both static and dynamic, delivered to the customer one year to six months in advance of the civil works.

Salu2

Dear Mr Guest:

Thanks for your input.

it sounds exactly like what the customer should have done upon dicovery of the cracks, and seems he has just noticed them now. No idea since when exist.

To track progress of the cracks will not be possible, because the plant will begin the pre-Christmas scheduled shut-down next week. This matter should be sorted out before Christmas.

The control of dimensions/levels/position is something I do regularly, but is good to have it reminded.

I will get back with the inspection sightings, hopefully next week.

Salu2

Perhaps a different view. Let's define the problem. Customer says oil bubbling fr on cracks in concrete at base of machine. I am not surprised at cracks after 6 years at heavy loadings . I am not surprised that as machine operates the entrapped oil 'bubbles' in cracks. I am not surprised that management allowed oil spillage to occur. I am surprised that your client thinks of sand as an oil absorber. I would define the following problems: groundwater contamination by unknown quantity of oil pooled beneath your concrete. Of wells or creeks are nearby could become serious problem sooner rather than eventually. To determine if cracks are significant due a survey to indicate the movement or float of the equipment and or floor sections. Surveyor transit or lasers can be used to quantify this. This could then be rechecked at intervals . I'd be really more concerned about the fugitive oil than any degradation of concrete strength effects. Milo

Dear Milo,

the foundation is 2m above ground level, with a mass of 1500t.

Rough dimensions of the block are L10m, W10m,h5m (2m above & 3m under floor level)

Total load:8250kN (5400 static +2850 dynamic load)

About sand as absorber... a would consider it more like a "thickener" to allow shovel removal. Nothing more. Hopefully the discarded materials will be properly disposed of.

The survey would had been great to keep records as you say, but neither the customer took care of it, nor it is possible now. The plant is stopped actually.

The amount of oil, I do expect to be a very visible but small quantity. Mostly some spillages during maintenance, change of components, some seal drop leak, etc.

In the system there are interlocks that would alert in case of leakage (we are talking of a Gearbox with 4500 liters of VG320, a lubrication circuit with 1500 liters of VG320, and an Hydraulic system of 2000 liters VG68, all of them tank and pipes included).

Many thanks for your coments and hints.

Best regards,

Not mentioned by the OP is the size and frequency of the cracks. Information regarding the depths and widths would be welcome, as it's no possible from our vantage point if the cracks are due to:

1. A design flaw, especially in regard to dynamic force loadings in addition to static loadings.

2. Inferior construction techniques.

3. Inferior concrete, especially compressive strength.

4. Ineffective or non-existent concrete curing techniques.....possibility the cracks are caused by excessive shrinkage.

Is the equipment foundation raised above shop floor, as in it's a equipment pad? If so, that may nearly eliminate the groundwater wicking issue.

Washing the oil out of the cracks, even with detergent-based solvents, may not be effective. Depending on the depth and breadth of the cracking you may have to chip out the bad concrete down to sound clean concrete and replace with a cementious-based epoxy patching product that exhibits very high tensile, rupture, elongation, flexural and compressive strengths (greater than the specified concrete properties). Of course this may be impossible to undertake if the cracking has occurred under the equipment baseplates.

Is the equipment mentioned some sort of gas or steam turbine / generator? At 450 tons this is my guess. Is this equipment to be operated during any field investigation and subsequent repair?

Some investigative tools to be employed:

A. Destructive testing would involve coring the concrete foundation, at locations that include the cracked concrete areas to determine their extent, and areas where there is no cracking so as to perform concrete strength testing. The testing would include both concrete compressive strength testing,and pietrographic analysis of the specimens (cores) to ascertain concrete constituents.

B. Non-destructive testing would involve Windsor probe testing to ascertain concrete compressive strengths. Depending on the size of the foundation, this should be done multiple times to determine the mean values.

That's preliminary info for you until we know additional information.

We use brake fluid to get oil out of cement pads.

Pour it on and let it soak in, it brings oil to top and then we vacuum it up and wipe it up with oil adsorbent cloth or we use oil adsorbent in a bag and then shovel it up.

Brake fluid works good.

They may have a similar "engineered" product specific for oil like oil eating bacteria fluid or similar. Like they used on the oil spill in the gulf.

As for cracking, I would consult an expert in cement not a civil engineering firm. I know a P.E. engineer who is an expert in cement and teaches this subject at University. But you would have to fly him out to spain all expenses paid.

Dear all,

finally seen it by myself and it came out a less serious issue than expected.

There were no cracks in the foundation, just gaps produced between the mainframe and the concrete due to small shrinkage of the concrete. (gaps were found to be =/<0,5mm width and 22-25mm depth, same of the frame plate thickness).

To ascertain there was no mechanical isues with the gearbox supported, the historical of vibration was examined and, to ensure no deformation in the metal parts, gaps between gearbox and seat plate, as well as lifting effect due to stressed assembly , was verified installing dial gauges at the corners, and releasing the anchor bolts. No problem from that side.

After cleaning the base, an impact "hollow detector" (or hammer) helped to determine the areas afected, and the job for the civil works began with the preparation for the resin injection in the areas. Unfortunately I did not remain there for that part, since I am only mechanical supervisor for the equipment, but customer took the proper steps to stop the problem before further develop, as recommended (with all your kind help).

Best regards, and many thanks for your support in "civil land".

@Capt Moosie, the heavy equipment is a vertical roller mill. VRM.

@Gizmo787, It is installed in a cement factory. They know about, and have the means to check all about the cement and concrete by themselves now, but not at the time of factory construction. Although sometimes "In house of th blacksmith, wooden knife"

Thanks for letting us know abelmh.

I like the saying - a simliar we use is "The cobbler's children go barefoot".

I've been following and not contributing. No point there was enough intelligence being demonstrated.

But yeh...that proverb was a pearler and I like your's too.

Not so different to "The mechanic's car is never fixed". We could create others.

I don't feel so bad about my own WIP living environment now.

Many thanks to the OP who took the time to let us know the outcome and for staying in the loop with useful feedback (feed forward?).