On the surface, concrete seems to be able to last a lifetime. Afterall it is still one of the most durable construction materials in the world. There are concrete structures in the world such as the Roman buildings that are over 1000 years old. Unfortunately times have changed, in many instances concrete today, no longer live up to expectation because of myriad of factors which we shall address in a short while.
Of all building materials, concrete is the most abused, because often time people do not adhere to the concrete correct specifications. Another enemy that has contributed to the shortening of concrete life is water.
Water carries chemical contaminants into the concrete, it can erode the surface, corrode the steel reinforcement, cause alkali aggregate reaction (AAR) among other things. Therefore the first step in preserving your concrete is to do everything you can to keep water out of your concrete.
Below are few other suggestions for ensuring the durability of your concrete:
- Low Permeability
The Durability of concrete is defined by its ability to resist deteriorating influences, which may reside inside the concrete itself, or which are present in the environment to which the concrete is exposed. In this part of the world, the most common carriers of these deteriorating influences are water. Therefore the lower the permeability of the concrete the more durable the concrete will be in the long run.
How do you ensure your concrete has low permeability? The simplest way is by using good mix design and importantly by using PRAH waterproofing admixtures and 3rd generation PCE plasticizers, Such as Aquafin Admix AQ100P and Remicrete Sp 56. Please see ACI 212 classification for waterproofing admixtures as not all waterproofing admixtures reduce permeability to keep out deteriorating influences.
- Concrete Mix Design
Concrete Mix design is the proportioning of the ingredient of concrete and determining their relative amount with the objective of producing a concrete of the required strength, Durability and workability. Durability starts with a concrete mix design that is properly matched to the use for which the concrete will be subjected to and the placement condition. No single mix design is ideal for all situations. For example, concrete mix design for a hot weather placement will most likely be different to concrete exposed to the cycles of freezing and thawing in a wet environment. The Portland Cement Association of America publishes a concrete design document, which contains an excellent guide to concrete mix design.
- Concrete Placement and Curing
Good concrete placement helps to secure the longetivity and protect the integrity of concrete. Concrete placement can be a challenging job, whether on large or small projects, without stating the obvious poor concrete placement especially in hot weather can affect concrete curing, the compressive strength and lead to crack on the concrete. Admixtures, especially in hot or cold weathers can help to achieve correct placement. It is also important that the concrete is properly vibrated during placements. Examples of admixtures that can help enhance workability and strength of concrete are Remicrete Sp 10 or Remicrete Sp56.
The greatest strength of concrete is also its greatest weakest. Concrete is not flexible, it doesn’t stretch or bend without cracking. But concrete does move-it shrinks, it expands, and different parts of a building move in different ways. This is where joints come into play. Construction joints are inevitable; unfortunately, they are also the common weak points in every structure.
Water penetrating through expansion joints can deteriorate your structure; corrode your reinforcements and sometimes your interiors. Be sure that you have factored in a reliable expansion joint treatment system like the induflex VK 2000 or the Induflex 6060 swellable polyuethathane joint sealants. It may also be necessary to use the expansion joint profile, depending on the specifications by the structural engineer.
To learn more about how to build concrete structures that will outlive their intended design life talk to the experts at Advanced Concrete Technologies (Schomburg Nigeria).