Nowadays, only crushed sand is only option available for making concrete due to over exploitation of natural river sand. But quality of crushed sand is always questionable due higher silt content ( ?) particle shape ( flaky ) due to poor rock quality. Gradation of sand need to be checked. Poor quality of crushed sand will affect workability , cement demand, strength and hydration of cement.
By conducting chemical and physical tests of sand and then using it in concrete and checking its mechanical properties
Please see:
Strength and durability of concrete with crushed sand
By: B Balapgol, S A Kulkarni and K M Bajoria
Make a comparative test. Make concrete using the sand in question and compare its properties with a concrete made using a definitely good sand.
Dear Sir,
Following Test for sand
You find in this link a thesis about concrete prapared with cruched sand :
http://thesis.univ-biskra.dz/2544/
please, see this profile :
https://www.researchgate.net/profile/Mohamed_Khouadjia
please, see this profile :
https://www.researchgate.net/profile/Mohamed_Khouadjia
http://www.cipremier.com/e107_files/downloads/Papers/100/27/100027021.pdf
If crushed sand is used as fine aggregae in concrete production, no need to go for flakyness index. Test like water absorption, particle size distribution, silt content, sp. gravity, bulking of sand and test for impurities can be performed to check its suitability.
Dear Friends thanks for your answers.
The point is that quality of crushed basically depends on quality of rock and crushing method. Particle size, shape and content of fines will affect workability . Then what are the limits of these parameters to get desired quality of concrete.?
Dear Ishwar, kindly specify exactly the desired quality in order to get a specific answer. However, and generally the crushed sand should follow the acceptance procedure of any fine aggregate type. As for the workability you should first specify the required slump and then prepare a number of trial mixes to select the most desirable one. Thank you
Use IS383 code book and follow the tests mentioned to test the quality of sand. Since it is a crushed sand i dont think organic impurities will be a issue. Sand should have less silt content and good grading which can be checked by sieve analysis.
In crushed sand (if getting from demolished concrete), the silt or dust can be removed by any of the method that is used in normal sand (e.g. washing). The crushed sand will require more water for desired slump because of high surface area. Other characteristics like soundness can be tested according to any prevailing standard. In general, crushed sand cause better strength
I advise you to read ASTM (AMERICAN SOCIETY FOR TESTING MATERIAL)
Test on silt and partIcals size distribution test according to IS383.
we get good results
By conducting chemical and physical tests of sand and then using it in concrete and checking its mechanical properties
First and foremost you should know about the source of the crushed sand i.e. type of stone extracted from. Then first you should check the strength by Abrasion and crushing strength and then go for the tests as we do for natural sand i.e. specific gravity, sieve & water absorption. Silt and organic impurities are nearly nil in this type of sand.
What I would do is to test whether the sand in question fits in the envelope of good sand while plotting in excel softwar.
The second is find the fineness modulus of around 2-3.
Thirdly find coefficient of uniformity and lastly find the amount of silt which should be less than 0.6%
- Badges
- Science topic