I just finished perofrming MVER testing on a recently placed concrete slab. As many of you may know, with the increased use of water-based flooring adhesives, the MVER of a concrete slab has become increasingly important. The emission rates on the slab in question were much higher than allowed...
I believe the smart Southerner from Georgia has clarified your estimating needs. As a common rule of thumb, most suppliers figure that it takes between 105 - 110 pounds of mix to install 1" over one square yard. Depends on a lot of factors - lower in-place compaction levels will obviously make...
OOPS, I forgot the main question:
As far as a layer coefficient, we usually use 110% to 130% of the layer coefficient for the virgin stone base beneath the in-place asphalt. Where I hail from, the stone base # is 0.18 for crushed aggregate base, so we use 0.20 to 0.24 for the CPR mixture...
After seeing CPR projects on numerous light duty roads and some small commercial parking lots, I have come to the conclusion that the greatest drawback to a recycled base is grade control. I don't care how well the recycled base is shaped, cured out, or compacted, you always have difficulty in...
Ron -
You like a chip seal better than paving fabric? Maybe I've just seen too many bad surface treatments in the past, but it always seems like the chip seals cause a tender mix (like the P-401 used in this situation on airports) to spread under the breakdown roller, thereby creating minor...
Anybody been reading the construction newsletters out lately?? If so, you have to notice that we have a very high demand for cement now - it's gotten so bad in some areas of the SE U.S., that cement suppliers have been rationing their product. Structural engineers can vouch for steel shortages...
VAD -
Thanks for your input. I also have regards about cold process recycling, but a local contractor uses one quite regularly around here. I don't think it's wise to disturb a relatively stable, but fractured 4" thick mass of asphalt.
I have obtained 18 full depth asphalt cores from both...
To all -
Doing a runway rehabilitation project in SE U.S. where the existing asphalt pavement is experiencing longitudinal cracking along joints (where lanes of paving match up). Some isolated transverse cracking beginning to appear where bitumen has begun to oxidize with age and tear at...
Two points
1)"pitted about 1/4 of an inch" - every supplier around these parts has a disclaimer about calcium stating that if not properly mixed, calcium 'balls' will develop. These are commonly seen on the surface as shallow pits. As a general rule, for every 1% of calcium used, mix the...
Big H -
Sounds like your client has the same specifier as one of our big box boys (the home improvement store that's not orange in color). Their spec says that contractor shall compact mix until 96% of Rice is achieved. If contractor does this, he/she has already killed all the voids that...
If field measured by obtaining cores, SCDOT specifies 91.6% to 96% of Rice (theoretical max) gravity. Older specs were compared to Marshall results, as the FAA still does.
I do not like comparisons to Marshall results - what if Marshall SG is low and compaction is poor in field - you still...
Big H -
This specification has reared its ugly head on SCDOT jobs for years. To get around it (when samples are only marginally above the PI spec of 13), we suggest to grading contractors that they blend fine sand with the material, thereby lowering the PI. SCDOT has also toyeed with the...
One quick comment -
The lean clays you have in the Raleigh area should be installed wet of optimum conditions. Even the slightest bit of 'dry-packing' can cause big problems when exposed to water. And, depending on the test method used to determine in-place density values, the material could...
Ask yourself three simple questions first -
1) Does the cut material contain a large amount of rock? If so, a dig & dump operation is the best
2) How wet is the material? Pans move plastic soils most effectively when they are around optimum moisture condition. Sands are generally moved...
PSlem -
$65 to $75 a site - now that has gone below board. You would have to do 300 houses a year to cover insurance deductibles if in a lawsuit for just one house.
Please do all consultants a favor and STOP THIS NONSENSE. It's bad enough that architects, owners, even other engineering...
Greatly depends on the weather forecast. In cold months, around here at least, subsoils directly beneath the topsoil are 2% to 6% above optimum moisture conditions. If one hopes to dry subsoils to allow for fill placement, best to strip topsoil as soon as a dry 'window' is forecast. A trick...
I do not believe it is referred to as 'AASHTO 57 stone', however, #57 stone as defined by quarries, state agencies, etc. is an aggregate blend of size 5, 6, & 7 stone. This material cannot be 'compacted' in a true sense, but can be properly oriented with compaction equipment. This is...
Good point SirAl - I agree with you that when surface defects are of interest, a Swiss Hammer is a good tool. I was referring to its use as a means of determining the structural integrity of concrete. Pressure from concrete producers has caused many consultants to do testing that they know is...
There can be several obstacles to using fabric - the greatest is perhaps mobilization costs - most true fabric installers will not give you a good price unless you have at least 15,000 SY to do. And believe me, you want to use an experienced fabric installer. A normal paving contractor usually...
Right on Focht3!! Living on the east coast, I don't see to many expansive clays like there are in Tejas. But, we do have some areas that are succeptible to differential settlement - I guess this would be similar to expansive clays, particularly if the strata varied across the footprint. If...
