Hi All,
What is the relation between theoretical density (as obtained by mix design ingredients values) and the actual fresh concrete density tested? Is there any acceptance tolerance on unit weight on declared values? The concrete is non-air entrained.
Please your views.
Hi,
Please advise what standards/codes we can refer to close a low compressive strength case where in a set of 6 cylinder samples taken from one composite sample, 1 result is fail and the other 5 are okay. The concrete grade is 45 Mpa.
Results are as below
56.1 Mpa
46.4 Mpa
40.3 Mpa
53.5 Mpa...
Please see another wall photo with same concrete but different surface. This time nice regular shade !!
Please need your support to find the root cause...http://files.engineering.com/getfile.aspx?folder=1f9ff72e-24c3-4c55-9cac-0849246dc108&file=IMG_3520.JPG
Epoxybot - No, there was no addition of water in the forms or bleed water escaped. The slump was little higher around 240mm but the mix was cohesive with no segregation or bleeding. The area shown with exposed aggregate is due to chipping done for some repair and that is not so important. The...
There are 2 structures A & B.
Dimensions of A 2mx2mx2m
Dimensions of B 30mx2mx10m
Thermo couplers were used in record peak temperatures in the concrete core. The placement concrete temp is same in both the pours and ambient temp is constant also. Please choose the right answer,
a. The peak...
epoxybot - They are the same color. The upper part is under shade so looking slightly dark color. The point is look at the lower part of the wall which is very uniform in color. There are no variations in concrete color as seen in post 26 Dec 17 12:01.
How can we get uniform color of concrete...
The wall surface is compared between two contractors A & B. The above issue of variations in color of concrete walls is with contractor A, whereas contractor B (different package in the same project) has been able to produce uniform colour/shade of the walls (please see attached pic). I could...
Good day!
Attached is another photo where one piece is totally light and uniform color than the rest of the wall !! The supplied concrete is same and all records are verified okay for w/c and flyash. Still this variation in shade is not understood. ANy ideas to share...
Please see the latest pictures of wall surface casted showing variable concrete shades. What I suspect is below,
a. Variable rates of formwork oil application
b. Formwork surface
c. Difference in flyash color
d. Variable batch to batch w/c
Kindly share your views.
Thanks in...
Hello All,
Please see the crack mapping report for a section of tunnel slab. The pattern is typical cutting the length perpendicular. The red color cracks are full depth (60 cm)
Kindly put some more light on the causes and reasons for these cracks. Will be grateful if supported by some...
Thank you all for your comments.
Ambient temperature at the time of placement = 36 Deg C
There were no windy conditions in general.
Each tunnel section is 30 meters long (without any joints). The joints are between each section. So the spacing is 30 meters.
Superplasticizer was added at the...
Hi,
There are horizontal cracks (0.1 to 0.5mm wide)running horizontally every 3-4 meters on the top of a metro cut and cover tunnel slab which is 0.6 meters thick. The cracks run full depth of the slab with water leaking at the bottom.
Concrete Information:
Mix is OPC+FA+MS C35 ASTM Slump...
Please see the attached photo of the tunnel wall. Flyash color cannot be controlled as per the flyash supplier. What solutions we can implement to have uniform color of concrete walls?http://files.engineering.com/getfile.aspx?folder=f77481e0-0649-4386-9c7d-f79d4cb6c026&file=wallcolor.jpg
Hello All,
We are troubled with change in color of concrete in METRO tunnel wall. The wall is 30 m long and casted in multiple lifts 500-1000mm thick at one time. In this 6.5m meter wall, we see color layers have different colors, from light to dark grey. The concrete supplier says that it is...
Concrete placement done by pumps and vibrated properly. Curing was done using curing compound.
The third party inspection agency concluded that the cracks are due to early thermal contraction. Are these not due to lack of expansion joint because the length of the wall is 30 meters ! Please see...
Hello
A concrete tunnel wall (30m length x 6.5 m height x 1.2 m thick) cast using 35 Mpa triple blended concrete mix saw vertical cracks(please see attachment) from the kicker up to mid height and diminishing at top. The fresh concrete temperature at placement was kept under control at 28 Deg...
Hi,
What is minimum concrete compressive strength required before a concrete block (2mx2mx2m) is lifted using a crane at 3 days without causing damages or broken edges.
Hello Everyone,
Please see the attached photo of slab soffit where random cracks have developed. Also there are plastic shrinkage cracks at the slab surface.
Kindly explain reasons
http://files.engineering.com/getfile.aspx?folder=0ea2551d-3047-4446-a61a-664a7e13e96a&file=a.jpg
