Lime Concrete

Q I am designing for a hurricane area for clients who has requested that I find a “healthy” concrete (they don’t like regular concrete). The building system will be a hollow block with fiberglass rebar and concrete infill. The walls will be placed on a monolithic concrete slab foundation. Is it possible to use lime concrete for such structural demands? Is lime concrete more human-nervous-system-friendly than regular concrete?

A We produced some simple concrete mix designs for a customer based on 25 kg bags of NHL. Taking a normal concrete mix of 2 parts stone to 1 part sand we checked the voidage, as per normal mortar design. This resulted in a mix of 1 bag NHL to 20 litres of sand and 40 litres of gravel, this would vary depending on the particular sand or stone. The water demand for a normal concrete consistency was only slightly higher than would be required for a cement concrete, i.e. around water: lime ratio of 0.6 giving a density of 2220 kg/m3. Strengths were as predicted from mortar adjusted for the water content at:
NHL 2 28 days = 2.5 N/mm2; 56 days = 3.5 N/mm2; at 91 days = 4 N/mm2; and at 1 year estimated 6 N/mm2.
NHL 3.5 28 days = 5 N/mm2; 56 days = 7 N/mm2; at 91 days = 9 N/mm2; and at 1 year estimated 12 N/mm2.
NHL 5 28 days = 7 N/mm2; 56 days = 11 N/mm2; at 91 days = 13 N/mm2; and at 1 year estimated 16 N/mm2.
Diluting mixes to 1 bag NHL to 30 litres of sand and 60 litres of gravel reduced strengths by 33% of the 20 litres / 40 litres mix.
Diluting mixes to 1 bag NHL to 40 litres of sand and 70 litres of gravel reduced strengths by 50% of the 20 litres / 40 litres mix.
Using a similar design method it should be possible to arrive at a mix suitable for the engineering requirements of this, or any other, job.