Self Compacting Concrete

[Ingenuity]

Self Compacting Concrete (SCC) has been used in Japan for more than a decade and it currently accounts for about 50% of all concrete placed in that country, and within the next few years it is expected to exceed 80%. Big numbers!

I have read several technical articles about SCC and it appears that Japan and parts of Europe have really taken the technical lead in this field. I am aware that ACI is doing a bit of work on this subject but things seem to be rather behind compared to Japan and Europe.

I am particularly interested in any US experiences (good and bad), or comments from others from around the world who have some experience with this "exciting" material.


By SCC I do not mean just flowable concrete that has lots of HRWRA and segregates. I mean non-segregating concrete, that is highly flowable, that needs NO compaction, and provides a good dense matrix that has "high performance" (good strength and durability) characteristics.

TIA

PS I probably should have posted this in the Concrete Engineering forum, but given that there are more than 3000 + members in the strcutural forum compared to 800 + in the Concrete Engineering forum, i wanted more "bang" for my thread without double posting!

I also did a search of previous threads and came up with a blank!

 

[valleyboy]

I haven't used this material myself, but have recently been on a seminar run by a concrete supplier who was trying to peddle the stuff on the UK market.

First impressions suggest that it is a pretty amazing material. I have seen laboratory testing carried out on SCC. If you carry out a slump test, the material immediately drops to form a 'puddle' of concrete, without seggregation, or bleeding etc. Another test comprises a transparent plastic 'box', with plastic rods which imitate rebar placed closely together. Sure enough, the concrete can clearly be seen to flow between the rebar.

I'm not sure how widely used this material is on the UK market yet, but I know that the Building Research Establishment have been investigating possible uses for SCC. You will find some further information on the following :

http://www.bre.co.uk/press/2001/august/060801scc.html

I can certainly see applications where SCC will have a clear advantage over traditional concrete, such as instances where the bar reinforcement is very close together, or possible uses for underwater concrete.

 

[Taro]

I have not used SCC, but I recently read a informative article on it by M.K. Hurd in Concrete Construction magazine, January 2002. She says that SCC has been used quite successfully by North American precasters, but has not gained much popularity for cast-in-place concrete yet because of a lack of standards and specifications. ACI and ASTM are just now getting into the picture to develop standard tests, etc.

 

[Ingenuity]

valleyboy,

thanks for the weblink - that chimney suface sure looks slick.


taro,

i think i read the same article from HURD. Seems like we will see more SCC in the years to come.

thanks for your comments.

I can also see applications in the repair of concrete structures where you have soffit repairs to beams with rebar/PT congestions and you need to form and pump. You could eliminate most of the usual problems like multiple entry ports etc and would just have to bleed air at discrete locations.

For new construction on say tall walls, seems that form pressures will be noticably increased due to the flowability, but probably small price to pay given the advantages. Tall walls with mid-height window recesses can be a real pain to pour successfully without getting voids etc. then patching etc.

I also understand that you can increase the SCC free-fall height compared to "conventional" concrete.