We were discussing about sustainable concrete in respect of conserving fine aggregates. Now-a-day, exhausting of natural resources, degradation of environment and global warming are considered in every aspects of development, especially in construction and studies to introduce sustainable construction are funding all over the world. Our concern, as civil engineer, is construction materials, process and applications.
In regard to fine aggregates, now partial replacement of sand and even complete replacement with waste residue are studied and a new concrete named sandless concrete is also studying where all fines are omitted. We will discuss all of these in our next posts.
Demand of concrete as construction material is increasing with time and as fine aggregates if we use river sand following impact on environment and existing structures are observed:
a. Natural resource (sand) is exploited by this process
b. Water table is lowered
c. Structures like bridge piers may be sunk as consequence of extraction of excessive sand etc.
Not only as fine aggregates but also as coarse aggregates, crushed glass was studied; but a reduction in workability of concrete is observed which in turn affect on compressive strength of concrete. The workability reduction will be discussed in our next pos. It is to keep in mind that some deleterious reaction is observed due to siliceous nature of glass like alkali-silica reaction (ASR). We will discuss about ASR elaborately in upcoming posts.