Dear researchers,
Recently, i have got a question about the replacement methods on recycled aggregate concrete. Some literatures reported that the natural aggregates could be replaced by mass when using the recycled coarse aggregate sourced from some abandoned concrete members, when the orginal coarse aggregates content is determined, the replacement content can be very easy to be calculated. When considering the ceramic tile (or lightweight materials) as the replacement material, however, some publised papers noted that the volumn replacement method could be better for calculating the weight per cubic meter of concrete (a density conversion factor was considered, see Article Mechanical properties of concrete utilising waste ceramic as...
). But, when using the volumn repalcement method equation, hardly can i calculate the values the literatures presented (seeArticle Porcelain and red ceramic wastes used as replacements for co...
,Article Steel chip and porcelain ceramic wastes used as replacements...
), and the calculated values had an obvious deviation. But the values calculated by the same equation from the literature (Article Mechanical properties of concrete utilising waste ceramic as...
) almost had a negligible difference from the values the literature reported. I guess that the deviation resulted from the density values, anyone with good suggestions is greatly appreciated.Yours sincerely,
Qingsong Zhou
Dear Mr. Bayan Hussien, Thank you so much for your kind suggestion.
Yes, when considering the concrete waste demolished from the abondaned concrete members, using percent by weight can serve very well.
However, it seems unreasonable when taking the lightweight replacement material (such as some kind of waste ceramic tiles, shale ceramsites) into consideration, for the reason that the weight replacement method will consume a large number of lightweight materials when considering a large replacement ratio.
For the first approximation, it is sufficient to use the weight percentage. At the same time, for direct replacement, it is necessary to know the bulk density, which is affected by porosity and density. The chemical and mineralogical composition of the material and some of its mechanical properties have a great influence.
The significance of these properties may vary with respect to the overall composition of the concrete and the desired properties of the concrete.
The greater the similarity of the properties of the concrete components, the greater the similarity of the concrete from the replaced materials can be.
Dear Mr. Jaroslav Stoklasa,
Thanks a lot, an excellent answer! I have got the apparent density of the alternative material in my research, which has been used to calculate the weight per cubic meter of concrete (taking volumn replacement method).
Dear Mr.Zhou
The volume replacement method is the correct method to replacement the fine or coarse aggregate
It is always good to consider replacement by weight. When recycled aggregate is used either from ceramic tile or concrete waste, in both the case due to its properties, unit weight of both materials are different. so volume replacement may not give true picture for parameter under study.
Dear Zhou,
There is no specific conversion factor for substituting natural aggregate with recycled concrete aggregates. To do it best, first you should make samples out of your concrete wastes and make cubic (or cylindrical) samples and test for its mechanical properties (compressive strength, porosity, etc). Note that recycles aggregate usually has higher porosity and a rougher surface with higher water absorption and it's compressive strength is usually less. So depending on the application (load bearing or non-load bearing), the amount of replacement would change.
Dear Ferdowsi,
I had a doubt in your opinion mentioned above, generally recycled aggregate (without Impurities) will show moderate increase in compressive strength than the recycled aggregate with impurities and conventional aggregate. These results obtained based on the literature and field study.
If it is wrong can you just suggest some recommendation.
Thank you and regards
Balamurali
By identifying the major chemicals present in waste and segregating them, we can substitute the original costly materials.
Yes, u can but u need to study the factor that affect the engineering properties.. If ur waste testifies then u can. Many parameters like chemical compositions, particle size, dry density..etc come into the picture...
You have to find out
1. Which kind of cheap- reusable eco-friendly options are there in your region
2. What will be side-effect of the material if it is used
3. What will be the quality of the the product
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