Hi,
We have observed spalling of concrete upon de-shuttering the soffit formwork after 25 days. The concrete slab is 2.0 meter thickness and was poured using 45 Mpa mix with 35% flyash to meet heat of hydration requirements as the thickness is 2.0 meters.
Test cylinder samples have achieved...
Hi All,
Please classify the crack shown in the uploaded pic. Other data is as below,
1. Concrete grade 45 Mpa (490 Kgs cement)
2. Pumped @ 100 meters
3. Initial water curing not done. Curing membrane was applied late.
4. Slab thickness 40cm & 70cm.
Also recommend measures to control such...
Hi All,
We have a situation where early shrinkage cracks occured after 1-2 hours of the concrete was placed. Enclosed are the pics of these cracks. The grade of concrete is 45 Mpa (flow upto 600mm) and was pumped up 16 storeys by placing boom. Ambient temp was 41 deg centigrade max.. concrete...
Hi All,
We tend to ignore the volume of heavy rebars in any structure while ordering the concrete. Given that the yield of the concrete is allright, there remains some difference between theorotical quantities ordered (based on the dimensions from the drawings, offcourse) and the actual...
I got shocker of my life to know the compressive strength @ 60 days of a 45 Mpa mix containing 35% replacement of cement with PFA (Type F C618) and about 5% of microsilica C1240, to be almost equal to 28 days strength. Only minor increase of 2 Mpa has occured @ 60 days.
I reckon the cause to be...
Hi,
What is the difference between sand equivalent test values and sa simple silt content test?I mean when you finish a SE test, specs say that min 75% SE value is accepatable, which means max 25% of clay/silt content is acceptable limit for sand used in structural concrete! But other specs say...
Hi,
To calculate proportions by weight of a plaster mix 1 : 4 by volume we need to multiply the dry densities of cement & sand with the volume proportions. How much cubic of fresh plaster mix does it give you after mixing with water say W/C = 0.45 ?
Absolute vol method of calculating the...
Hi,
What is the difference between sand equivalent test values and sa simple silt content test?
I mean when you finish a SE test, specs say that min 75% SE value is accepatable, which means max 25% of clay/silt content is acceptable limit for sand used in structural concrete! But other specs...
Hi there,
We have a different mixes with cement varying from 400 to 480 Kgs/ cum. The W/C is kept constant = 0.35 for all the mixes. The mixes are like this
Cement W/C %Dosage
400 0.35 0.5%
420 0.35 ??
440 0.35 ??
460 0.35 ??
480 0.35 ??
Now, the first...
Hi there,
We have a different mixes with cement varying from 400 to 480 Kgs/ cum. The W/C is kept constant = 0.35 for all the mixes. The mixes are like this
Cement W/C %Dosage
400 0.35 0.5%
420 0.35 ??
440 0.35 ??
460 0.35 ??
480 0.35 ??
Now, the first...
Dear Friends,
We have Project specifying asphalt wearing course 50mm thick average laid over concrete deck (350mm thick). Between the two there lies a 4mm thick torch applied waterproofing membrane. Now, when you apply the membrane to the concrete and lay hot-mix asphalt wearing course 50mm...
