Composite reinforcement: blende or reliable material? Design Engineer Answer
Can composite rebar be used to reinforce foundations, basement walls, slabs and other monolithic reinforced concrete elements? Artyom Polorchyan, a design engineer, an active participant of FORUMHOUSE, answers the question.
Composite reinforcement through the eyes of a layman
I will try to imagine for a while that I am not an engineer and that I am very far from the topic of construction. How can I decide whether to use composite reinforcement in the structures of my future home or not? After all, as they say: “My home is my fortress” and somehow I don't really want this fortress to be plastic.
In the place of a simple layman, I would first of all ask my acquaintances or neighbors on the site, what they heard about this miracle. Sellers assure that this is a good saving in materials because composite reinforcement is much stronger than metal and due to this, a smaller diameter can be used. It costs less and, plus everything, is four times lighter.
It seems to me that in this case no one would clearly explain anything to me, as well as the manufacturers of this product. You can also pay attention to multi-storey construction, because professionals work there, who calculate the economic benefits of this event and if composite reinforcement has so many advantages, and even cheaper, then these guys have definitely been using it for a long time and save a lot, and as a result, they earn. But there is little information about this product. Most likely, I would have remained at a loss from such a technological innovation and purchased a time-tested steel reinforcement.
Composite reinforcement through the eyes of a professional
Over the 10 years of my work, I have been at various facilities, including industrial ones, as field supervision, or on a survey, and nowhere have I seen the use of this type of reinforcement. I could have stopped at this, but I'm an engineer, so I will give a few boring numbers. You don't need to be an expert to not understand them.
On July 11, 2017, by order of the Ministry of Construction, Housing and Utilities of the Russian Federation, it was approved: SP 295 SP 295.1325800.2017 Concrete structures reinforced with polymer composite reinforcement. Design rules. This set of rules was introduced on 12/01/2018.
If you open this joint venture, then, in principle, the calculation method is the same as when designing with metal reinforcement. But if we pay attention to the table, we will really see that the tensile strength of plastic reinforcement on average almost 2 times higher than that of conventional reinforcement, but the tensile modulus of fiberglass is 45000 MPa, and that of ordinary one is 200000 MPa. The difference is significant! So just due to the fact that the modulus of elasticity is small compared to conventional reinforcement, the destruction of a structure with fiberglass reinforcement will be brittle, i.e. it will occur not on tensioned reinforcement (the meaning of any calculation), but on compressed concrete. Simply put, plastic reinforcement is stronger, but fragile and when maximum loads are reached, the reinforcement breaks, and does not stretch like normal. In this regard, if the structure is damaged, there will be no time for evacuation from the emergency room!
And also there is no experience in the use of plastic reinforcement in structures, i.e. when calculating, an error is possible that you will not notice. For example, I counted 100 monolithic beams or floor slabs and already by experience you know what the approximate will be result, and if the result is very different from the expected, then you start looking for an error in calculation. If you don’t find a mistake, then you will turn to your colleagues, in extreme cases when the object is very complex - to specialists from the expertise. So, no one can help with composite reinforcement - there is no design experience!
Conclusion
I think that composite rebar will find its niche in construction, but at the moment, I would not use it in critical structures such as foundations, columns, floor slabs, beams and etc. I believe that composite reinforcement can be used in structures such as floors on the ground, entrance groups, blind area reinforcement, etc., i.e. all irresponsible constructions, where moments and concentrated forces do not arise.
What do you think of composite rebar? Write your application experience in the comments.
You learned something new - like it - support the project and we will publish relevant and useful information about construction for you!
Useful articles: how to learn how to cook with a welding inverter; 20 best projects of country houses. Watch the video- Problems with gasification at home: we solve legal issues with registration.