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Rapid hardening cement

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Rapid hardening cement develops strength at a higher rate compared to ordinary portland cement. The strength produced at 2 days by RHC equal 7 days strength of OPC if some w/c ratio used. The strength of RHP will equalize with OPC after 2 to 3 months. The reason behind developing early strength is the increase of C3A and C3S and due to increasing the fineness (min 3250 cm2/gm)of the cement. Increase the fineness of cement, and the amount of C3A and C3S will result in a higher rate of hydration and rapid gaining of strength. 
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The RHC is chemically similar to OPC. Therefore the designing of concrete mix will be similar as if OPC used. The initial setting of rapid hardening concrete is 60 minutes or more. The RHC will gain 30% of it is compressive strength in the first 24 hours. RHC has the following advantages:

  •  RHC curing period is less than OPC, which reduce the time and cost of construction.
  • RHC is good at Sulphur resistance.
  • Using of RHC will allow for quicker removal of the formwork, which reduces the time and cost of construction.
The uses of RHC:

  • RHC will allow early removal of formwork. It can be used where formwork has to be removed as early as possible to reuse it.
  • It can be used in freezing weather. The high rate of hydration will generate a high temperature which prevents the frost of water in the capillary of concrete.
  • It can be used in the precast industry. using RHC will speed up the process and allow efficient utilizing of the formwork
  • It is generally used for constructing road pavements, where it is vital to open the road to traffic quickly.

RHC should not be used for water-retaining structures. RHC generating high amounts of heat internally as a result of rapid hydration. The heat will create and increase the shrinkage cracks. These cracks will allow the ingress of an aggressive chemical such as chloride and sulfate. These chemicals will cause steel corrosion and destructive concrete expansion which lead to the reduction of structure service life and early deterioration.  

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Mohammad
My name is Mohammad Hamdan, and I am a Civil/bridge Engineer with extensive professional background and experience in the field of construction. I have 10+ years of experience in the construction field. During my professional career, my emphasis has been placed on structural projects, mainly bridges, infrastructure and roads. Reading and practicing the design of structures is my passion.i was lucky to be a part of a big team that executed major highway interchanges. I believe in spreading the knowledge, thus, i compose these courses to share my experience and knowledge. My course focuses on the practical side of construction field. On other word, i am sharing some of what new engineers need to know about construction field. Beside working on construction field, i love writing some articles on my website ( curious civil engineer) Moreover, i wrote some engineering papers, you can check them  by searching my name on Google (Mohammad mamon Hamdan)