Explaining Quality Control of Concrete

[00:00:02]I just gave a presentation on quality control in general and the industries in general so what is quality control of concrete now collective control of concrete is different than what the control of most manufactured products because it's a live manufacturing process it is not you do it in the factory and you define it and then you you sell it so while quality control of concrete is in the process of manufacturing the concrete sending the concrete pouring the concrete waiting before f2 to set and then watering it so that it becomes reaches the required strength and taking care of the concrete not to crack we have shrinkage cracks expansion cracks drawing cracks and so on so one of the control of concrete is it's much more complicated than most people think okay so how to do quality control now quality control concrete is done in in more than one step there is a quality control that you have to do at the precast concrete or ready mix concrete factory which is within a closed environment and there is a quality control which you have to do when you transfer a transfer this manufactured material to the site to its final destination so you can see there isn't a totally one quality control aspect also before you design any construction engineers and designers will define the strength of the concrete the quality of the concrete the mix design a lot of things are definitely predefined and when they predefined those items they go into testing and they start actually doing field trials using the defined parameters and modify until they reach what is an acceptable mix this now once you start the project and you are delivering and pouring the mix design that is approved by the contractor and the consultant then we start monitoring the quality of the country and this is where the civil engineer was required all the time to measure the strength of the concrete so one of the major requirements what the strength of but really there is much more than that because the strength of the concrete is may be a primary objective but there is other things like whether the concrete will shrink whether the concrete have cracks in it from extreme weather conditions or water vapor and so on so there are a lot of things that have to do with the construction phase of concrete and this is usually taken care of by the civil engineer and by the project manager and by the supervisors but there is also another quality control which is extremely important and this is the reason why we do for example density tests air content tests some of the lab tests that we will do which many people somehow they don't know why we're doing it all the time why are we all the time checking checking the density the density is something that it doesn't change too much why are we checking all the time tests well the reason for that is it's a quality control but it is more in the direction of uniform production you want the product to be uniform uniform meaning that I am getting similar results today like a good yesterday like I got the day before like I got the day before like about the day before and if I'm doing this then my my product is uniform so if the product changes I will say why did it change maybe just the temperature was 20 degrees and now it's 40 degrees so this change in temperature will change the product so we have to make a modification somewhere else so that we keep the product the same quality even though the temperature is higher maybe I will maybe the ready-mixed company changed their cement source so I should get that feeling because I was checking the consistency of the quality the quality changed why did it change maybe the supplier of the aggregates maybe his crusher is not working well the aggregate shapes are not very nice not as uniform as so so what is happening is that we are in the labs doing repeated work which may be boring for civil engineers okay but you should look at it as a very important step because what you're doing is you are going to catch major mistakes if they happen early on I mean the worst case scenario will be to find a mistake in your mix design and in you mix properties one month after it's already been poured then you are talking about demolishing the big disaster so this is why the laboratories and the testing of the laboratories has more than one function one function is to test the quality the second function is to test continuity of the product so if the truck driver who is delivering concrete does not rotate his mixer all the time you can notice it on site and if he rotated more than he should you will see it on the site somehow in a change of that product so consistency becomes very important and imagine if you have a drawing which show you for example air content of concrete and then it is 3% 3% peepers and 2% P percent 2% and 5% then 1% 2% 3% 4% 6% so what does that mean this means when you got this high what air content something happened something happened you have to investigate it and see why what happened that caused that kind of a change and in the air content now of course most of us don't care too much about our content we take it for granted but really air content is something that is could be very important if I was buying ten cubic meters of concrete with an air content of 1% or 5% then I am paying five percent more for air when I buy it for five percent and if my project demands air content of five percent and what I get is 2 percent then my building will be will be 3 4 % heavier so I have to take that weight into consideration so we see air content is also important so lots of those small items that people sometimes don't look don't understand why they are important whoever puts them in has a reason for and that consistency of the production will make consistency of the project and once the project is well designed and well monitored during construction then the possibility of having a better project is much more achievable thank you very much