week 10

Tuesday:
tutorial with Keith, more people turned up and we were able to get more clarity on the project and what the brief required. between the group the majority of information we need has been gathered, although no one can find construction details for the building

afternoon:
Concrete-
David Bennett on behalf of the Concrete Centre

Handcrafted Concrete
*mixing- colour
*pouring- formwork
*finishing

material characteristics and usage

Reduction of CO2 in concrete
- Portland Cement - really high CO2 - 1/6th ingredients
every ton of cement made 1 ton CO2 released

Main way to reduce CO2
- Ground rendated iron ore slag - cement - 50kg CO2 per ton
- Pulverised Coal Ash- 5kg CO2 per ton

can then use recycled glass

-> best way to reduce CO2 in construction is to consider energy use in processing.

Visual Concrete specification
- Specification
- workmanship
- Achievement


Gravel 20mm-4mm inert & non absorbent
Sand 4mm- dust Inert and non absorbent
concrete dust strength and 85% cost


Colour rules:
1. finest particle goes to surface
2. pigments must be finer than cement particles
3. sand colour tints concrete
cement is grey due to levels of iron-> iron levels vary between quarries - stick to same supplier/quarry
4. water content.

everything is measured in m^3 because everything arrives on site pre mixed

cement- 325 is minimum

- weigh materials then convert back to volume

2 parts sand to 1 concrete
- incresing sand increases cost

4parts gravel - course aggregate
- gravel> crushed stone
(rule greater 6 parts to 1 cement - can reduce sand for stone)

80% 20-10mm

woodcrete- wood must be wet to not absorb water needed by concrete

concrete requires 1/4 its weight water to set- rest of waster is used to make sand/gravel homogeneous.

Water- cement ratio must not exceed 0.5

- plasticiser -> makes the concrete repel water for a time making concrete more fluid for a time.

Slump test
- must be between 125-175 drop for walls/ slabs.

Compacting
- 0.5m layers then compact

-placing rate 3m/hr

-drop compactor to bottom then pull up slowly - dont compact the entire thing at the end, only do the layer.


Lecture was very clear and concise, gave very clear a specific examples and instructions for what is possible with concrete and how to achieve it. also made a very clear case for concrete as a low carbon material. all around a very good lecture.





Thursday: