How to repair serious segregation in reinforced concrete?

When we work in building projects we absolutely deal with concrete, concrete is a famous construction material which consist mainly from cement, gravel aggregate, water and other chemical additives to a achieve or increase some required properties like workability, but when we cast a densely reinforced concrete elements with reinforcements bars, we might have concrete segregation .

So with all these concrete additives used and long experience with concrete mix design, sometimes we surprised with some segregations here or there in the concrete elements maybe due to too much compacting or not enough compacting or the workability of concrete is not enough . Some of these segregation can be repaired easily when it is on the surface with cemented materials like Rendrock FC, but others needs to be casted again with special materials conbextra HF which has a very low shrinkage Coefficient and high compression strength, in this article we will negotiate serious segregation which needs to be cast again with conbextra HF.

conbextra HF

Steps to follow to repair serious segregation with materials for construction solutions:

1.       Firstly we should remove all the loose or none dense concrete parts till we have a dense layer of concrete and clean steel reinforcement, we also Wash the surface to clean it from dust and then wait to dry.

2.       We paint the old surface of concrete to be in contact with a glue material   to increase the  sticking relation between the old concrete and the new material, then we have about 4 hours to finish the rest of job till the set of this material as shown in picture below.

the segregated area painted with the glue material

3.       Then we surround the segregated area with sealant material like silicon materials to prevent the seepage of liquid mixture to flow between the shuttering formwork and concrete surface (we should give this matter special care because the material can flow the smallest spaces of shuttering).

4.       We start the shuttering process from one or both sides it depends on the depth of segregation, then we leave a small hole to cast the cemented material from it.

5.       We prepare an 18 litter bucket, drill, mixer arm fixed to the drill, clean water with temperature degree not less than 22C◦.

6.         Pouring 4.5 litter of water in 18 litter bucket then start adding the conbextra HFslowly on it while mixing with the drill , we continue mixing till we have a homogeneous workable solution, then casting it from the hole, we repeat this process till we fill the segregated volume(while casting the mixture we don't have to compact).

the mixing process 

7.       After 24 hours we remove the shuttering and we have the result as we see in the following picture.

this article  written by Taha Mesleh working as an experience civil  engineer in the field of building and contracting ,with Abaad contracting company if you want to read similar articles visit:construction-and-architecture.plogspot.com