The key drivers of the development of HSC are the long term use of concrete construction, the design of taller buildings, and the growing demand for thinner columns or wall elements to create more open-planned spaces.

The requirements for HSC are evolving, and will likely continue to change:

1. The design of NZ Concrete Structures code, NZS 3101:2006, limits the use of HSC to 70 MPa for seismic design requirements (ductility).
2. Other structures can be designed using concrete strengths up to 100 MPa.

HSC is produced through an optimised use of the raw materials used in standard concrete

Most producers of HSC understand the factors that affect compressive strength and have the knowledge to engineer them to achieve their desired concrete strength.

The selection of raw materials is of utmost importance before they can be optimised into the required mix design:

• High Quality Portland Cement
• Supplementary Cementitious Materials (SCMs)
• Aggregates
• Admixtures

High Strength Concretes are more sensitive to changes in constituent material properties than conventional concretes. This means they require a greater degree of quality control for a successful production.

EverSure Type GP is manufactured at Golden Bay, and consistently meets the requirements to produce High Strength Concrete.

Including Microsilica and EverPlus Class C Fly Ash will provide the additional properties required from a Supplementary Cementitious Material for High Strength Concrete:

• Microsilica SF: through a pozzolanic reaction that produces additional calcium silicate hydrates, Microsilica improves concrete strength. It also offers a fine powder packing mechanism and the improvement of bonding at the aggregate paste interface.
• EverPlus Class C Fly Ash: also through the same pozzolanic reaction, EverPlus Class C Fly Ash improves long-term concrete strength and durability. The spherical particle shape of the EverPlus Class C Fly Ash assists with controlling water content, and improving mix rheology and concrete pump ability.