HOW TO SHOW CURING OF CONCRETE ACTIVITY

• a disjoint between working calendars (ie. between the casting task and the curing task’s successor - assuming that curing is a 24 hour calendar)
• the casting task has some other successors with a lessor float path than the curing task

Valdimir,

To understand CASTING OF CONCRETE-FS-CURING ACTIVITY link, you better have an idea about Concrete Technology & Practice.

Technology says; 

After concrete poured in place, it will start setting withing 3 hours of time (initial setting) & finish setting by 10 hours.

you must start curing immediately after initial setting time of concrete finished.

Practice is;

If slab this is possible, but for columns & walls its already covered so you can cure only top part which is very small area.

Concrete will gain more than 66% of strength in seven days & 100% of strength in 28 days. As long as the concrete can take (3 to 7 days) enough strength the form work can be removed & the start curing immediately.

So, in case of wall if you say curing for seven days it will consume total 10 days if you wait for striking form works in columns after 3 days. so, leaving form works in column also is one type of curing as it not allowing to dry columns.

So the FS is correct irrelevant to other activities for ASTING OF CONCRETE-FS-CURING ACTIVITY link.

Rizwan.

Hi Rizwan,

I have an idea about Concrete Technology & Practice.

Your explanations confirm that concreting and curing activities shall have the same total floats.

Best Regards,

Vladimir

Kumar,

Scenario 1:

For Car park Slab ; there is no superstructure on it . with the curing the activity is completed.

Scenario 2:

For Ground floor Slab; the continuous curing for 7 days must start immediately after concrete casted & wait till ground slab to take load of form works for 1st floor. You will definitely have Zero Float for this.

Scenario 3:

If you make concrete cube sample casted on site & make curing with the structure in actual condition , and you tested the cube in 3 or 4 or 5 or 6 days as proof of sufficient concrete strength was gained at site to stop curing then & go to next activity (which is the best practice specially for precast slabs, still can be used to other areas of concrete )

Scenario 4:

Don't show the curing activity separately just say 'Concrete Casting & Curing' as one activity & make sure successor activity based on this will have lag 7 days. Hope this is very simple Not a Problem of Float.

Rizwan.

Valdimir,

To reinforce my comments check this scenarios;

Scenario 1:

For Car park Slab ; there is no superstructure on it . with the curing the activity is completed.

Scenario 2:

For Ground floor Slab; the continuous curing for 7 days must start immediately after concrete casted & wait till ground slab to take load of form works for 1st floor. You will definitely have Zero Float for this.

Scenario 3:

If you make concrete cube sample casted on site & make curing with the structure in actual condition , and you tested the cube in 3 or 4 or 5 or 6 days as proof of sufficient concrete strength was gained at site to stop curing then & go to next activity (which is the best practice specially for precast slabs, still can be used to other areas of concrete )

Scenario 4:

Don't show the curing activity separately just say 'Concrete Casting & Curing' as one activity & make sure successor activity based on this will have lag 7 days. Hope this is very simple Not a Problem of Float.

Rizwan.

You can define that activity as a "Level of Effort" activity.

Rizvan,

I don't know the software that you use but in Spider Project concreting and curing may be delayed only together and thus have the same float.

Best Regards,

Vladimir

Vladimir,

If we have a job in which curing is specified to be done by “Fog Curing” and we have a lot of concrete and a limited amount of Fog Curing equipment then our pours can be limited by the availability of this resource.

Curing is an activity that must start almost immediately after concrete pouring, usually starts before the end of big pours. Therefore, the link between concrete pouring and curing must be a “strong link”.

Take a look at the following schedules:

1. The first schedule screen is from a sample job before leveling.
2. The second is from a leveled schedule without using strong links.
3. The third is from a leveled schedule using strong links. In Spider Project Strong Link option prohibits increasing lag between activities in resource constrained scheduling.

I believe this was one of the wishes from our friend David Kelly, a very relevant wish. Spider Project got a solution that yields a workable solution that in occasions can be near optimal or even optimal but in others will not. Seems like a very complicated resource-leveling issue that the more activities you add to the train it becomes exponentially more difficult to solve, maybe a compromise to limit the model to two continuous activities will help to solve most of the issues (a single strong link per activity) very close to optimal.

Although not used frequently "strong links" are very useful functionality when you need it, I would like to see this functionality also on logic links.

Because we do not use fog curing here I do not need to resource load the curing activity, as a matter of fact we use a FS lag for these purposes even when not considered to be a "good practice" by many, here even people out of the construction business know concrete must be cured and need no further explanation for the lag when they look at the schedule. With Spider Project this is even easier as we can define the lag calendar to be Calendar days while preceding and succeeding activities use other calendars of their own while other software complicate such simple thing.

Regards,

Rafael

Hi Kumar

Yhis is the only time that I use a FS link with a lead lag that is set to the approriate number of calendar days.

For a slab you may need to outgoing links - 1. to remove forms say 3 days 2. to remove props say 28 days

Best regards

Mike Testro