Abstract
This paper presents the results of a study into the use of fine aggregate from construction and demolition waste (C&DW) in the South African construction industry, and the impact this has on the important fresh and hardened properties of concrete when used as partial replacement for virgin materials. The C&DW were tested at replacement levels of 0%, 25%, 50%, 75% and 100%. The recycled fine aggregate was pre-soaked to mitigate the expected effect of higher water absorption of recycled concrete aggregate (RCA). However, pre-soaking of the fines attributed to the poor performance of the fresh and hardened properties of the concrete. The pre-soaking procedure used was problematic when used with fine aggregates and caused a large amount of excess water to be added to the concrete mix as a result. This study highlights the importance of planning the demolition process of a structure to ensure that the best possible quality of RCA can be extracted. The study revealed that the use of recycled fine aggregate as a replacement of virgin materials in the manufacture of concrete has a much greater negative impact than the use of coarse recycled aggregates. In addition, the pre-soaking procedure of fine aggregates warrants special attention.
Highlights
For many years and across the globe, the use of natural resources and the abuse of the environment have been seen as necessary “costs of development”, but recently the drive for a greener, more sustainable construction industry has been on the rise worldwide
This international trend has resulted in a rethink of the construction industry as a whole worldwide, resulting in what is known as sustainable development, which the Bruntland Report defines as: “Development that meets the needs of the present, without compromising
One of the material classification tests that was performed on the sand, was the relative density (RD) test
Summary
For many years and across the globe, the use of natural resources and the abuse of the environment have been seen as necessary “costs of development”, but recently the drive for a greener, more sustainable construction industry has been on the rise worldwide. The introduction of green building rating with systems such as those employed by Leadership in Energy and Environmental Design (LEED) in the United States of America and the Green Star rating system in South Africa (SA) have changed the global view of green technology This change in public perception has led to the demand, and subsequently, the value of including of “green” properties in materials has being on the rise. According to the triple bottom line theorem of Sustainable Development, Sustainable Development comprises of three main parts, namely: Economic-, Environment- and Social factors [1] All three of these factors need to be considered and balanced in order to make a project or product as sustainable as possible and meet the “Triple Bottom Line” of sustainable development
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