crackes

[jay]

just wondering. concrete house slabs, new ones has anyone noticed they seem to crack a lot more these days any thoughts on why// seem that all new slabs are cracking up for whatever reason would it be they dont use vibrating screeds any more :20:

 

[Rob Z]

Hi Jay, We don't have much SOG construction around here where I live so I don't see much concrete that is going to get tile. Basements of course are all concrete, and the garages, but I can't say that they are lately looking better or worse than what I am used to seeing. Do you think in your area they are skimping on the wire or getting too much slump on the mix to try and make it easier to work?

 

[jay]

hi rob it seems to cover most of oz only thing i can put it down to is they dont use vibrating screeds anymore they use lasers to find levels then hand screed so mix is wetter but i dont know :20:

 

[Rob Z]

hi rob it seems to cover most of oz only thing i can put it down to is they dont use vibrating screeds anymore they use lasers to find levels then hand screed so mix is wetter but i dont know :20:

Jay, I see some seriously wet, slumpy concrete coming out of the back of the mix trucks. I know the low budget cheap ba stards aren't paying for any plasiticizers so it's all water in there there.:mad2: Cracks ahoy!

 

[Ajax123]

There are probably loads of reasons for the cracking. We see it in the UK as well. cheaper (lower quality) cements, weaker mixes, lower skill levels in concrete finishing, lack of curing regime, groundworkers needing (notice not likeing but it is a time thing I guess) an easy life so asking for the concrete to be wet up on site are just a few of the contributary factors. Mostly lead by matrial cost unfortunatley. Problem is that many builders and QS's don't look further than the material costs. for about 35% more mone on materials you can get really good quality self compacting concretes which come with a curing agent as part of the package. These sorts of materials can actually save quite a lot of cash for a builder if he is prepared to look at the "big picture" in terms of time savings, less remdial works etc etc......

Not sure what it is like in Tas but in general in the UK I just don't think we build things very well and the attitude " a good tiler/brickie/plasterer etc etc will get over that" i.e. cover up the problems rather than design them out. I find this really frustrating

 

[jay]

thanks ajax123 thats along the lines i was thinking i was just curious if the prob was more common and it seems to be they dont seem to be shrinkage cracks deffo more major thanks again:8:

 

[Ajax123]

thanks ajax123 thats along the lines i was thinking i was just curious if the prob was more common and it seems to be they dont seem to be shrinkage cracks deffo more major thanks again:8:

shrinkage and lack of compaction are the two major causes I come across. Both so easily avoided but people don't bother. It is something the UK industry is looking at tackling in the bulk housing market certainly by using more modern construction methods e.g. Timber floors with calcium sulphate screeds and the like. Thing is though if we just stopped rushing evrything so much and people stopped wetting up their concrete so much and included a simple suring regime (7 days) into their build programme the problem would almost certainly go away.

Neither of these used to be such an issue because the cement contents of the concretes were much higher and so could withstand abuse by contractors. Nowadays though the suppliers like everyone else are so tight on costs due to the big squeezes put on costs mean that thinkgs are stipped to the bone. e.g. house floors used to be 4:2:1 mix concrete - something like 270kg cement per cubic meter. Nowadays it is a Gen 1 which is 175kg per cubic meter. You can't add 200liters of water to your batch an expect it to perform but people still do it.....:mad2:

 

[jay]

in other words laziness:8:thanks

 

[Ajax123]

in other words laziness:8:thanks

not always laziness on the part of the contractor. lot of time they are forced into a position where they have to sut corners due to pricing issues. Only way they can earn a living is to cut corners - also lack of technical knowledge as to what the implications of what they do are.....but yes Laziness plays a bug part.....

 

[jay]

bring back vibrators (concrete screed types i mean):lol: