Alternatives to river sand for construction

Rabinder Shekhar
The demand for SAND as a building material has now increased manifold due to the ever increasing growth of construction industry and major infrastructure projects all over the country. In Jammu, we have a number of small, medium and mega structures coming up and the demand of the sand has increased exorbitantly. This has led to acute dearth of river sand for the construction purposes, resulting hike in the prices of sand in Jammu & Kashmir vis-à-vis India. Sand is mined from the rivers and is a practice that is used to extract sand, mainly through an open pit. However, sand is also mined from beaches, inlands dunes and dredges from ocean beds and usually river beds. Sand is used in construction industry to form concrete. As communities grow, construction requires less wood and more concrete whether we go horizontal or vertical construction, leading to a demand for low-cost sand.. Further, sand is also used to replace eroded coastline. Sand mining is becoming an environmental issue in India and the environmentalists have raised public awareness of illegible sand mafia and sand mining in India. Almost all dailies have highlighted the public wrath and even an I.A.S. officer has to bear the anguish of UP Govt. Sand mining has environmental impacts also. They can be broadly enlisted as follows:
* Reduces the water head, so less percolation of rain water in the river beds resulting lower ground water level (GWL).
* Damaging the regime channel flow of the rivers.
* Erosion of nearby land due to excess sand lifting.
* Disturbance due to digging for sand and lifting destroys the flora & fauna in the surrounding area
* The greed of man and vested interests and the demand for the sand is responsible for the illegal sand lifting or sand mining
* It has become a major issue throughout the country and the world
* There are many conflicts between the politicians, bureaucrats and sand suppliers due to illegal mining now a day.
Awaaz Foundation and Bombay Natural History Society (BNHS) created awareness against coastal sand mining for the first time in national or International forum at UN in October2012. The need of hour is to ban the sand mining from rivers. In Jammu region, sand is lifted from almost all rivers and the time is not far away, when we shall be forced to think of  similar awareness here too. So it the right time for we engineers to ponder upon the issue and to find out the “ALTERNATIVES TO RIVER SAND” if we have to carry on with the construction industry smoothly for the years to come.
It looks very strange when one says that there can be no alternative to river sand. But  of history reveals that the old forts and palaces were constructed with surkhi and lime and no sand was used. The sand was used as construction material when cement made its debut as construction principal material. Today researchers world over are in continuous search for the alternatives to river sand. Fine aggregate is one of the important constituents of concrete. River sand is becoming very scarce and sand mining from rivers has become objectionably excessive. It has now reached a stage where it is killing all our rivers day by day so sand mining has to be discouraged by the engineers for all type of construction. We, the engineers, should come to the rescue of our rivers in their resign channel formation and providing a laminar flow of the rivers in plane areas. There are a number of alternative materials available for replacement of river sand. Some  alternatives to sand are:
* Fly ash/Bottom ash/Pond Ash
Three types of ash are produced by the thermal plants namely Fly Ash, Bottom Ash and Pond Ash. Fly Ash is collected by mechanical or electrostatic precipitators from the flue gases of power plants, whereas, bottom ash is collected from the bottom of boilers. Pond ash is the by-product of thermal plants, which is considered as a waste material and its disposal is a major problem from an environmental point of view and also it requires a lot of disposal area. Further, when two types of ash, Fly ash and bottom ash are mixed together and transported in the form of slurry and stored in a lagoon, the deposit is called Pond ash. The ash can is used as an alternative to river sand. It has many advantages also like
i. The strength of concrete increases with respect to percentage of slag added by weight to fine aggregate up to
ii. 40% of addition
iii. The recommended % replacement of sand by copper slag is 40%
iv. The addition of slag in concrete does not have any environmental problem.
* Filtered sand and Sea Sand
The use of filtered sand and sea sand have posed many challenges to the engineers as many of the concrete structures failed using the filtered sand and sea sand. Many PMCs’ and monitoring authorities have raised serious concerns over the use of such type of sands for concreting. TOI reports the concerns expressed by the Lokayukta on the use of  “filtered Sand” at the construction sites in May 2008 and also report was sent to state governments on ” Filtered sand” being used by the engineers in construction sites and recommended for its immediate stoppage. The engineers have reported problems in using the sea sand. But, however, if proper filtration/washing is done of the sand, the same can be used effectively for construction industry. Although the sea sand also contains higher percentages of chlorides which increase corrosion in steel and higher contents of shales make the sand finer than the river sand, thus decreasing the strength of concrete. The Sri Lanka Land Reclamation and development corporation in association with civil engineering department of the University of Moratuwa and the national building research organization have carried out some studies and recommend sea sand as sustainable alternative to river sand. The sea sand taken from the off shore area has low salinity level than sand of beaches, so can be used as an alternative. Countries such as UK,Netherlands, India,Seychelles Islands, Singapore, Japan and Kotrea are using sea sand for construction although this type of sand is a dream for Jammu and Kashmir as the sea is far off from J&K and the transportation shall be very high. In Japan and Great Britain, which produce two-thirds of the world’s marine aggregates, offshore sand and gravel mining have already become a 200 million USD industry.
* Manufactured Sand
Manufactured sand popularly known by several manes such as Crushed sand, Rock sand, Green Sand, Robo Sand, Poabs Sand, Barmac Sand, Pozzolan sand etc. IS383-1970(reaffirmed 2007) recognizes manufactured sand as “Crushed stone Sand” under clause 2 of the code. Crushed stone sand is produced by Rock-on-rock, or Rock-on-metal Vertical Shaft Impactor (VSI). This type of sand is not a new concept but the attempts to produce crushed or manufactured sand in India could be traced to early 50’s primarily in major dams works. The absence of research in the reputed Civil Engineering Institutions about manufactured sand aided a lot of unscrupulous quarry operators to perpetuate the myth that quarry dust can be used in production of concrete either by complete or partial replacement of river sand. M-Sand can be used for making masonry mortar and shall conform to the requirements of IS2116-1980(reaffirmed-1998)-“specification of sand for Masonry mortars” M-Sand is available almost in every state and in our state the M-sand is used for very limited purposes and the engineers have not advocated for the sand. It has not become popular in construction industry because of the fact that the stone crushed are not dust free and the sand produced by the machines contain higher percentage of dust, not acceptable for concreting.
Time to think over the issue of alternative to River sand:
The civil engineers, architects, builders, and contractors agree that river sand, which is available today, is deficient in many respects. It is exhausting very fast and the government have put ban on lifting sand from river beds. Transportation of sand damages the roads and removing sand from the river beds impact the environment, as the water table goes deeper and ultimately dry. It should be noted only that all the sand particles should have higher crushing strength. The surface texture of the particles should be smooth. The edges of the particles should be grounded and the ratio of fines below 600 microns in sand should not be less than 30%. Silt in M-Sand should not be more than 2% and the permissible limit of fines below 75 microns shall not exceed15%. The artificial sand produced by the machines can be thus a better substitute to the RIVER SAND. Such sand will be more economical and demand for such type shall be increasing day by day if we advocate it and recommend the same. One should note that natural RIVER SAND takes millions of years to form so we should stop transportation of river sand. The government should also come forward to help preserve the rivers by “Banning mining of river bed sand” otherwise time is not far away that our rivers shall be flowing in anger and spate, damaging the ecological cycle.
(The author is Asstt. Executive Engineer in Civil Engineering and presently on deputation to SMVD Shrine Board and former Honorary secretary Institution of Engineers (India) Jammu Local center)

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