Hi, I need expert opinion on possible reasons for cracks shown in attached pictures.
Element - basement ground slab
Thickness - 450mm
RF details - T1, T2, B1, B2-T16@200 (QT bars)
Clear cover - 50mm
Ambient temperature during casting - 27-30 Celsius. (Sri Lanka 6pm to 6am)
Mix design (kg/m³)...
Hi Friends,
Recently I experienced a bit high variation of our strength results of C50 ready-mix concrete purchasing for slabs and columns casting. We expect 37.5 N/mm2 as 7 days strength for C50 (i.e. 75% of design strength as per Sri Lanka Standards). Can anybody help me on following...
Hi,
Is there any guidelines for installing copper tape (of lightening protection system) within reinforced concrete? I noticed that a copper tape runs in concrete slab just rest on the rebar net. Is it OK? Isn't there any risk of affecting inhabitants during lightening?
Thanks.
Hi friends I came again with a new issue at my project.
As the photo shown, there are 10mm starter bars around all core walls which is difficult to handle as we cast the core wall 02 levels higher in advance than the working level for ease of supporting placing boom. Our procedure has to break...
Hi, Please see attached photo showing spreading electrical conduits over 140mm thick slab. Cover to steel is no issue but I doubt about amount of concrete actually in the slab as conduits consume considerable volume. I'm searching for limitations, if any, for amount of voids allocation withing a...
Hi, I am currently involving in construction of 50 storied building.
Would you please to share some guidelines/specifications/documents regarding "quality assurance in high rise building construction"? I need to prepare a quality assurance plan for project that include what quality matters...
In our site, in which still secant pile construction in progress, we experienced concrete had been hardened rapidly (in less than initial setting time) in several piles along the boundary closer to sea. This pile line is about 120m from sea.
Could you please state possible reasons for this and...
Case in my site:
Structural designer specified to keep 25mm cover to concrete walls and columns for fire protection and due to unrecoverable mistake we had to cut concrete layer in one side of column up to reinforcement bars to align particular column with others. Next, column should be...
Image shows that partially cut concrete surface in a bath room for inserting gully box, which could not be placed during concreting. There is 10mm tor steel bar (hogging steel for slab over beam), which is @175mm C/C. Imagine gully box location cannot be moved and steel bar should have to been...
Dear friends, usually we crush test cubes at 7, 14 and 28 days after casting and use attached figure to verify the compressive strength. But sometimes we missed exact date. May be we have to crush it on 10th or 29th day due to practical matters occurred at site. So I want to know if there is any...
Hi guys, Can anybody explain the reasons for appearing concrete surfaces of columns (Grade 30) which are shown in pictures attached? Also please explain remedial actions could be taken.
Thanks....http://files.engineering.com/getfile.aspx?folder=a8e5cddf-dcb1-4802-a414-9f84b3dba6af&file=SAM_0804.JPG
Picture shows horizontal crack runs along the column just under the ramp at 3rd and 4th levels of structure. Still the building is under construction and just completed 4th level slab/ramp concreting. Foundation is a piling system rest on bed rock. Anybody can explain what are the reasons for...
