RECYCLED GLASS
A Potential Natural Sand
Replacement in Concrete
AUGUST 2011
Under the Sustainability Concept, a joint partnership project was agreed between the NSW Road and Traffic Authority (RTA), the NSW Department of Environment, Climate Change and Water (DECCW) in order to assess the technical and economic performance of recycled glass as a partial natural sand replacement in concrete.
The glass as natural sand replacement in concrete trials was a crushed product with a size distribution of between 3mm - 0.3mm. The clear and green glass was very clean with no materials passing 150 and 75 micron fractions.
The crushed glass has been tested for Alkali Silica Reaction and different combinations of glass replacement, with and without fly ash. A constant slump of 60 + 10mm, concrete with glass sand had marginally lower W/(C+FA) ratios. The air content and bleeding are slightly higher for all mixes using crushed glass as natural sand replacement. In addition, the setting time becomes much longer and it increases with the amount of glass sand added to the mix.
It has been established that crushed glass sand can be used to partially replace the natural sand to produce concrete with at least equivalent mechanical properties of a concrete mix using natural aggregate only.
Durable concrete is expected when glass sand is used to partially replace natural sand. The alkali silica reaction results show that the glass sand used in this project is acceptable as an aggregate. Data from this project indicates that better durability can be achieved when crushed glass sand is used in concrete mixes.
RECYCLED PRODUCTS FOR SUSTAINABILITY
NOVEMBER 2010
Recycled concrete products, particularly the Envirocrete, has similar properties to extracted rock products – concrete is made up of quarry products and has been very successful in the application of pavement products in road construction, particularly in low traffic sub-divisions.
There has been success for recycled concrete to be utilized for lower strength concrete production. It is a quarry product, it is high quality aggregate so you can always potentially recycle it. We split the materials up, take the sand and the aggregate out and send them back to concrete plants. Some companies add thirty percent (30%) of the total crushed product into their concrete mixes. There are restrictions on the use of recycled construction materials in higher grade concrete.
The end use of recycled construction materials is mainly in the lower sub-base areas of road construction, landscaping in parks and gardens, council work and in commercial developments such as factories and car parks. It can also be used in site preparation for large concrete slabs. By blending excavation rock and concrete, top of the range specified recycled products are produced.
When you add crushed concrete to quarry scalp materials it breaks down the clay (PI%) and stabilizes the lower grade scalps, therefore it becomes a far stronger, more suitable product.
WASTE BECOMES PRODUCT:
BLENDING THE OLD WITH THE NEW
AUGUST 2010
As quality rock deposits narrow, some quarries are considering alternative products comprising C&D waste.
EBH Environmental Services actively recycles over 85 per cent of all materials that it collects from its projects. EBH Environmental Services is also a dedicated timber
recycling specialist and retailer.
However, of most interest to the quarrying industry is EBH Environmental’s concrete and brick recycling. This very successful venture to crush, process and treat commercial demolished concrete into a new product called Envirocrete – the equivalent of various grades of quarry products – for roadworks, carparks, factory sites and landscaping purposes.
Twenty years ago most C&D waste material went straight to landfill or less regulated sites. However, in the last three decades, market forces, couple with State and Local Government regulation and a push towards more sustainable policies by clients, have inadvertently combined to drive the demand for alternative recycled products.
Therefore, it is much cheaper, not to mention more environmentally friendly, for clients to take their C&D waste to recycling plants like EBH Environmental Services than it is for them to send it to landfill.