Diamer Basha Dam

The dam body is built with 17 million cubic meters of roller compacted concrete (RCC), together with further two million cubic meters of conventional concrete and shotcrete for slope stabilization, construction of the underground powerhouses and accessory tunnels. The dam, owned by WAPDA, will provide clean energy through an installed capacity of4,500 MW / 12 x 375 MW turbines.

While the start of RCC casting will come towards the end of 2022, CVC (Concrete Value Corp) and shotcrete casts at site are running at high daily rates. For this, Sika Pakistan has been supplying the Sika® ViscoCrete® range and Sigunit® alkali-free accelerator with deliveries that started in summer 2021.

The introduction of the new concrete mixes, to be cast both through pumps and buckets with low binder content and long slump life, showed segregation issues and too long setting times. The complete review of the mix design by changing the binders blend, grading curve, admixture dosage and air entrainer would have taken a long trials program and a new approval from the supervisors.

The approach of Sika Pakistan, through the use of the new Sika Sand App and Sika Concrete Mix Design App, could significantly reduce the number of trial mixes from about 10-15 mixes down to just three mixes.

An easy tailoring of the formulation of the admixture was quickly developed after the few checks with the digital tools. The analysis of sands and gravel performed by the mobile phone showed that the aggregate quality and fines content were appropriate.

The data imported from the Sand App into the Mix Design App demonstrated that the total paste volume and fines weight was acceptable for both a directly cast and a pumped concrete. The total water content of the mix measuredthrough the accelerated drying process – after deducting the aggregates absorption – matched the designed one, thus demonstrating that the aggregates’ absorption values were congruent.