DELVOCRETE  

Description

The Delvocrete system is a unique non-chloride chemical system that controls the dynamics of cement hydration by suspending the hydration process and re-activating it hours or even days later without loss of quality of the hardened shotcrete.

The Delvocrete system consists of two products: Delvocrete Stabiliser and Delvocrete Activator S. Delvocrete Stabiliser is a liquid admixture. When dispensed into wet or dry mixes at the batching plant, it fully stabilises the hydration process by forming a protective barrier around the cement particles. Hydration control with Delvocrete Stabiliser works with all types of cement minerals (C3S, C3A, C2S, C4AF and gypsum).

Delvocrete Activator S is a liquid additive. In order to re-activate shotcrete mixes stabilised with Delvocrete Stabiliser and to accelerate the hydration process, Delvocrete Activator S is added at the spraying nozzle like a normal accelerator.

  Uses

The Delvocrete system is suitable for all wet and dry shotcrete applications:

• Tunnelling : temporary support and final linings for road, railway and metro tunnels, mines, hydropower projects, sewers.
• Temporary and final slope stabilisation.
• Repairs to concrete structures.
• Grouting systems.
• Injection suspensions.

Benefits

With the Delvocrete system wet and dry shotcrete mixes remain fresh for any desired period of time, up to 3 days. This provides considerable benefits in batching and utilisation of shotcrete:

• Fully flexible delivery options for batched shotcrete.
• No cleaning of pumps or pipes during work interruptions.
• Complete use of wet and dry mixes.
• Reduced waste disposal.
• Simpler and lower risk construction programme thanks to better scheduling and easier planning.
• Time and cost saving allocation of material, equipment and manpower.
• Expensive bagged material can be replaced by economical jobsite mixes.
• Considerable savings of overall construction costs.
• Considerable reduction of rebound and dust.
• Higher early strengths.

  Packaging

Delvocrete Stabiliser is available in 25 ltr pails and 210 ltr drums.

Delvocrete Activator S is available in 210 ltr drums, in 1000 ltr containers and in bulk.

  Technical data*

  Application procedure

Delvo®crete Stabiliser

 Mixing

Dry-mix Shotcrete

Premix aggregates with cement. The water content should be between 3 - 6% by weight of the mixture. If the humidity is lower than 3%, water must be added to reach the required percentage.

Slowly add - manually or with a dosing device - the necessary quantity of Delvocrete Stabiliser under constant mixing and continue to mix for 2 - 3 minutes. If evenly distributed over dry-mix material (e.g. by spraying), mixing time can be reduced.

The addition of Delvocrete Stabiliser to the freshly mixed concrete is ideal. However, until upto 30 minutes after mixing of the dry-mix material the addition of Delvocrete Stabiliser presents no problems.

 Wet-mix Shotcrete

Pre-mix aggregates with cement and one half of the mixing water. With the remaining half of the mixing water, pre-mix a high performance superplasticiser. The Delvocrete Stabiliser should be added with continuous mixing. Normal mixing time is sufficient.

In the event of unexpected delays, a later addition of 0.6 - 1.0% of Delvocrete Stabiliser is possible to prolong storage time for a few hours.

 Consumption*

The recommended dosage of Delvocrete Stabiliser for a stabilisation of 3 to 72 hours is 0.6 - 2.0% by weight of the binder (cement + microsilica). Normal cement content should be 400 - 460 kg/m³. Specific dosages depend on cement type, mix design, ambient temperature and required stabilisation time.

Recommended minimum dosages:

 Consumption*

The required setting time and hence the necessary dosage are determined by the type of substrate and its water run off, by the temperature of the substrate and of the gunned material and by the reactive properties of the cement. The dosage of Delvocrete Activator S therefore ranges between 3 - 8%.

• Dosages indicated on this technical datasheet are to be used only as a guideline. To obtain accurate dosage rates, field tests have to be done with local cements, aggregates and conditions. It is recommended that your local MBT representative be consulted.

 Storage

Minimum storage temperature for Delvocrete Stabiliser is +1°C. Minimum storage temperatures for Delvocrete Activator S51 and 61 are +5°C and -10°C for S71. If Delvocrete Stabiliser and Activators have frozen, thaw at +1°C (Stabiliser) and +20°C (Activators) or above, and completely reconstitute with a mild mechanical agitation. Do not use pressurised air for agitation.

It is recommended that your local representative be consulted prior to the use of any products that were frozen. Maximum storage temperatures for Delvocrete Stabiliser and Activators is +60°C. Performance tests should always be carried out prior to use.

If stored under the above conditions, Delvocrete Stabiliser and Delvocrete Activator S51 and S71 have a shelf life of at least 6 months, Delvocrete Activator S61 has a shelf life of at least 12 months.

 Safety precautions

Delvocrete Stabiliser and Delvocrete Activator S are irritant fluids; therefore any contact with skin and eyes must be avoided. It is essential that safety glasses and rubber gloves always be worn during handling. In case of contact with eyes or skin, flush immediately with plenty of water and seek medical advice.

Typical mix design for a open time of 6 - 10 hours.

* slurry added at the nozzle

 Note

Field service, where provided, does not constitute supervisory responsibility. For additional information contact your local BASF representative.

BASF reserves the right to have the true cause of any difficulty determined by accepted test methods.

 Quality and care

All products originating from BASF's Dubai, UAE facility are manufactured under a management system independently certified to conform to the requirements of the quality, environmental and occupational health & safety standards ISO 9000, ISO 14001 and OHSAS 18001.

12/94 BASF-ME revised 05/2002