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...
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...
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...
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...
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
Hello.
Kindly give your advice on the below problem of cracks appearing in the bottom of slab,
Project: High rise building construction
Concrete Mix - C45 Flowing
Ambient temps - Min 25 to Max 45
Crack width range - 0.3 to 1.0 mm
Slab thickness - 300 mm
Time of cracks appearing - cannot be...
Hello Gentlemen,
We have a case where bottom 1 meter of concrete wall had late setting and did not achieve required strength at 28 days. Came out only 10% of fck. The bottom 5 meters is absolutely ok. Is there any quick method to remove the bottom 1 meter portion of concrete and replace with...
Hi There,
Situation: Concrete post-tensioned beams poured on top of bridge piers. These post-tensioned beams will carry concrete slab that will be deck asphalted for future traffic. During one pour of 300 cubic meters for around 20 such beams, 1 beam web showed delayed concrete setting. This...
Dear All;
Can someone help me locating any International Standard (ACI, ASTM, BS EN, CIRIA) that specifies;
1. MAX ALLOWABLE TEMPERATURE AT THE CORE OF A MASS CONCRETE STRUCTURE (THICKNESS > 1.0 METER)
2. MAX ALLOWABLE DIFFERENTIAL TEMPERATURE BETWEEN THE CORE AND THE SURFACE OF THE MASS...
Dear All
Upon deshuttering formwork on road barrier concrete casting the horizontal or longitudinal cracks are developing on-site as seen in the attached photo. Its new jersey crack as commonly know.
Anyone possibly ascertain the reasons and preventive measures?
Thanks in advance..
Dear All
Please see attached photos of late setting of concrete (concrete in one pour line did not set up to 70 Hrs after pouring). The structure is a water-tank wall and we as the Supervising Consultant of the project instructed the contractor to continue curing with hessian cloth covered for...
Dear All;
We received a complaint from one Owner of the building for cracks in the beam at 2nd floor of a 16 storeyed building; Below are details..
1. The building contains 16 floors
2. Design submittal 400 kg/cm² BS standards
3. Subject beam is 1.5 m thickness, 6 m length and 2 m width. Beam...
Situation:
Cylinders for columns failed to achieve strength at 28 days. Contractor wants to run rebound tests to ascertain strength of the columns.
I have made some calculations for Schmidt hammer test. As per ASTM C805 and ACI 228.1, correlation curves have to be established for each type of...
Dears
please analyze the defect encountered in the water tank wall. concrete is flowable 500mm poured at a hieght about 3.5m using mobile pump.
Kindly explain type od defect, REASONS AND REPAIR
THANKS
