05 July 2020

Case Study-Sika India

Enhancing pumpability of concrete in Highrise construction

A major challenge in the construction of highrise buildings is maintaining the vertical pumpability of concrete to big heights, while preserving its low viscosity. Sika’s ViscoCrete®  plasticizers do this job well. By IBRAHIM SHAIKH, SENIOR PRODUCT MANAGER, SIKA INDIA.

 

CHALLENGES:
Main challenges when concreting at great heights:
•    High performance concrete (HPC)
•    Conveying (Pumping) concrete to the required height
•    Workability (Flowability) over time
Most tall building projects use high performance concrete (HPC) which ranges from 50Mpa– 100Mpa
Requirement of HPC:
•    Very low water/Cement ratio generally less than 0.3
•    Considerably high cement content
•    Part of cement is replaced by cementitious materials
•    Use of High efficient  Superplasticizers
Challenges for Making High Performance concrete:
•    Variations in fine and coarse aggregates
•    Different source of cement with varying mineralogy
•    Different cementitious materials properties
•    Varying climatic conditions
A robust Superplasticizers is the solution to the above challenges - Sika® ViscoCrete® technology

Pumping concrete to the desired height
Because of very low water : cement ratio and high fines content, the concrete becomes very sticky, very viscous, and difficult to pump. Sika® ViscoCrete® technology helps in reducing the viscosity, yield stress, giving better fresh concrete behavior even at such a low water : binder ratio so that concrete can be pumped easily to the required height.
 
Workability over time:
To bring the concrete from long distances or site batched concrete, the concrete should have a minimum flow retention period of 2-3 hours for pumping and finishing, and it should set normally.
Sika® ViscoCrete® technology retention polymers help in retaining (workability) flowability for hours without any effect on the setting time of the concrete.

 

SIKA VISCOCRETE
Sika ViscoCrete Superplasticizers  use admixture technology based on new generation PCE polymers. PCE polymers are very versatile polymers unlike SNF polymers. PCE polymers are tailor made and can be designed according to specific requirements.
•    Adsorption speed
•    Water reduction
•    High workability
•    Reduced Stickiness
•    Stability / Viscosity
•    Slump retention without retardation
•    Less sensitive
According to above properties polymers could be formulated to achieve desired properties.
With the use of Sika ViscoCrete technology following properties could be well achieved:
•    Better fresh concrete behavior
•    Stable mix
•    Less viscous
•    Less stickiness
•    High water reduction
•    Slump flow retention without retardation
•    Durable concrete structure
•    Better cost performance
•    Easily pumpable to the desired height
•    Sustainable concrete mix




Leave a Comment

Name  
Email Address
(will not be published)    
Website
Comment