E In Situ Concrete/Large Precast Concrete

Contents

E1 MIXING/CASTING/CURING/SPRAYING IN SITU CONCRETE
E10 In situ concrete mixes, casting and curing
E11 Gun applied/sprayed concrete
E2 FORMWORK
E20 Formwork for in situ concrete
E3 Reinforcement
E30 Reinforcement for in situ concrete
E6 COMPOSITE CONSTRUCTION
E60 Precast/Composite concrete decking
E7 EARTH CONSTRUCTION
E70 Rammed earth walls
E71 Reused tyre and rammed earth walls
E72 Cob walls

E10 In situ concrete mixes, casting and curing

CONSIDER:
• Cement substitution:
-There are alternatives to Ordinary Portland Cement.
-Ground Granulated Blast Furnace Slag Aggregate Cement (GGBS).
-GGBS is a waste or by-product of steel production.
-70% of cement can be substituted by GGBS and as little as 30% in some situations.
-Readily available from many ready-mix plants.
-It is slower to set and strengthen so programmes need to acknowledge it.
• Lime: recycles CO₂, used in Limecrete.
-Lime and Limecrete is popular at CAT Centre for Alternative Technology.
-It's is softer than Cement-Concrete and it can be chiselled to make alterations.
• Magnacite- No CO₂ driven off.
-Eastern European Industry.
• PFA in common UK practice.

CONSIDER:
• Electricity Supply: ensure all sites are required to use a Green Tariff electricity supply throughout the works, commissioning and testing period and hand over the building to the Employer (Client) with the same Green Tariff electricity supply.

RECYCLE:
• Recycled demolition concrete crushed as aggregate in concrete.
• Recycled sewage turned into LESA Lightweight Expanded Sewage Aggregate for lightweight concrete.

RECYCLED OR SECONDARY AGGREGATE SUBSTITUTION
• There are 6000 m tonnes of stockpiles of secondary aggregates in the UK, waste products from other industrial processes.
• Recycled plastic as aggregate in concrete, as sand, fine and course aggregate substitutes.

AVOID:
• Cement & concrete.
• CO₂ driven off from chemical process and also generated in burning fossil fuel for the heating process.
• Cement production adds 8% of CO₂ globally, adding to global warming and climate change.

E11 Gun applied/sprayed concrete

CONSIDER:
• See E10

AVOID:
• See E10

E20 Formwork for in situ concrete

CONSIDER:
• Steel profiled deck permanent formwork for floors See G30
• Biodegradable Formwork release oil
• Recycleable Formwork, the manufacturer recycles it into more formwork
• BRE research on crushing formwork after use for landscape mulch See Q23
• Low leachate (but how low?)
• Recycled polystyrene void filling

E30 Reinforcement for in situ concrete

CONSIDER:
• Vehicle tyres are being reduced to rubber crumb, wire and fabric.
- wire is chopped into short lengths and used as an alternative means of reinforcing concrete and screed.

E60 Precast/composite concrete decking

CONSIDER:
• Exploiting the thermal mass of concrete floors and roofs.
• Dry constructions on top of floors to avoid screed and concrete toppings which reduce the likelihood of reuse at end o the building life.
• Concrete block and beam floors, blocks with high recycled content, beams with cement and aggregate substitution.
• Concrete plank floors for fast construction.
• Co-ordinate design of building and units to avoid cutting and waste.
• Consider use of recycled aggregate.
• Consider use of cement substitutes to reduce cement use. See E10.
• Consider hollow floors, reduce use of concrete and cement.
• Consider hollow floors, use in ventilation and pre-cooling of floors.
• If the thermal mass of the suspended ground floor is not to be exploited then the use of a lightweight high thermal insulation floor could be an alternative to consider.

E70 Rammed earth walls

CONSIDER:
• CAT publishe a design & construction guide.
• Use specialist designer/contractor.
• Use of subsoil in rammed earth walls.
• New Website launched Buro Happold PII project.

AVOID:
• Off-site disposal of excavation subsoil. See D20.

E71 Reused tyre and rammed earth walls

CONSIDER:
• CAT publish a design & construction guide.
• Use specialist designer/contractor.
• Use of subsoil in rammed earth walls.

AVOID:
• Off-site disposal of excavation subsoil. See D20.

E72 cob walls

CONSIDER:
• Waste excavated sub soils in wall construction.

AVOID:
• Off-site disposal of excavation subsoil. See D20.