Blasting near Fresh Concrete
Blasting near Fresh Concrete
(OP)
Hi,
I am a site engineer for a local public utility. We are installing a new 14'x14' reinforced cast-in-place box sewer. Our contractor has previously blasted rock encountered but has recently requested shortening the distance of the blasting operations to freshly placed concrete.
My question is: what are the distance and vibration (peak particle velocity) limits that we should adhere to when the new box slab is placed in relation to the blasting operations. The slab will be 50-100 feet away from the blasting, while the highest PPV we're been getting from monitoring is <1 (.4 -.8 ppv)
I found a study from the early 80's by Ralph Spears (http://w ww.concret econstruct ion.net/Im ages/Effec t%20of%20B lasting,%2 0Jarring,% 20and%20Ot her%20Tran sitory%20V ibrations% 20on%20Fre sh%20Concr ete_tcm45- 340996.pdf) and another (http: //www.conc reteconstr uction.net /Images/Ho w%20Do%20B lasting,%2 0Jarring,% 20and%20Ot her%20Shoc k%20Vibrat ions%20Aff ect%20Fres h%20Concre te__tcm45- 348668.pdf). Does anyone know of a more recent study/paper that might be relevant?
Thanks ahead for any assistance.
I am a site engineer for a local public utility. We are installing a new 14'x14' reinforced cast-in-place box sewer. Our contractor has previously blasted rock encountered but has recently requested shortening the distance of the blasting operations to freshly placed concrete.
My question is: what are the distance and vibration (peak particle velocity) limits that we should adhere to when the new box slab is placed in relation to the blasting operations. The slab will be 50-100 feet away from the blasting, while the highest PPV we're been getting from monitoring is <1 (.4 -.8 ppv)
I found a study from the early 80's by Ralph Spears (http://w
Thanks ahead for any assistance.





RE: Blasting near Fresh Concrete
RE: Blasting near Fresh Concrete
0.2 ips or less is recommended to avoid disturbing the public
Good resource, not more recent, but that makes no difference - see chapter 7:
Publication Number: EM 1110-2-3800
Title: Engineering and Design - Systematic Drilling and Blasting for Surface Excavations
http://1
RE: Blasting near Fresh Concrete
RE: Blasting near Fresh Concrete
Thanks!
RE: Blasting near Fresh Concrete
Regards,
Regards,
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RE: Blasting near Fresh Concrete
Here is another source I've found that I'm familiar with:
http://
h
I believe that the second link is more applicable.
other links
http://
Another of the Spears article:
http://w
And a TRB report
http://rip.trb.org/browse/dproject.asp?n=11461
Regards,
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RE: Blasting near Fresh Concrete
BigH...guess that was my bad. Thought this one would be taken care of before anything happened to the soil mechanics one.
RE: Blasting near Fresh Concrete
1. no blasting to take place within 8 m of concrete less than 3 days old
2. blasting near permanent works within 30 m shall be such that the peak particle velocites
a. do not exceed 300 mm/s for mass concrete greater than 450 mm thick; or new mass concrete that has developed 20MPa strength
b. 50 mm/s existing and new timber frame structures
c. 150 mm/s at transmission line structures.
RE: Blasting near Fresh Concrete
The old rule of thumb used to be that anything less than 50mm /sec would not produce new cracks in residential plaster and that something greater than 300 mm /sec is necesary to produce fresh cracks in igneous rock. So all the previously quoted values are in the ball park but if you need to get sophisticated , you need to ask what degree of confinement exists within the blast pattern ?? What type of detonation system is proposed ?? What is the influence of the local geology that will be transmitting the shock wave??
RE: Blasting near Fresh Concrete
RE: Blasting near Fresh Concrete
RE: Blasting near Fresh Concrete