But industry should consider alternatives to reduce demand
The supply of sand is likely to remain stable for the time being although there are uncertainties amid rising demand for sand by the construction industry.
That was the message in an article in the latest Construction Cost Review published recently by cost consultant Langdon & Seah.
The firm noted media stories last March when it was reported that several, if not, many projects in Shenzhen were using or had used ready mixed concrete with marine sand in it.
One such project that received widespread media attention was the Ping An International Finance Center in Shenzhen being built by state-owned giant China State Construction Engineering Corporation.
Among the 31 suppliers that got caught up in the incident were two units belonging to listed China Resources Cement (1313).
Sand used in concrete and mortars has to be clean and free from corrosive minerals.
“Because of this, dredged river sand has traditionally been the main supply source,” the consultant said.
But with the onset of media reports from Shenzhen, it noted that the use of marine sand suggested that the apparently insatiable demand for new buildings was “gradually exhausting this natural resource”.
Marine sand in general is a no-no for construction work if untreated because the increased chlorine content leads to corrosion of steel reinforcement in reinforced concrete structures.
The main source of river sand used in Hong Kong is from Guangdong Province.
Statistics from the Civil Engineering and Development Department show that imports of river sand have fallen from 1.94 million tonnes in 2008 to 1.48 million tonnes in 2012.
For the first five months of this year, the total was 546,758 tonnes.
Langdon & Seah noted that it was not the first time that Hong Kong has faced supply shortages.
There was an export ban in 2006 by the Ministry of Commerce and the General Administration of Customs but this was lifted in early 2007 when Hong Kong signed a trade co-operation mechanism on natural sand with the mainland under the framework of the Closer Economic Partnership Arrangement (CEPA).
This mechanism served to stabilize supply of river sand and in June last year, it was strengthened to meet the needs of Hong Kong’s major construction projects.
But Langdon & Seah said the mainland was facing shortages itself as demand far outstrips supply with many local governments imposing quotas that are adjusted downwards every year.
Guangdong, which previously had rich reserves, was in a particular bind, with licenced mining volume of 14 million tonnes hopelessly trying to meet annual demand of 100 million tonnes in 2012.
“Although Hong Kong needs only about 1.5 million tonnes a year, it would be hard to ensure that adequate supply can be maintained under such circumstances,” the article said.
The law of supply and demand would ensure that prices would go up if demand increased as supply was maintained as per the supply agreement.
Surprisingly, marine sand is allowed in concrete production in the mainland as long as the sand is washed and the chloride content reduced to 0.06 percent or less.
The problem is that there are no standards or government approved processes on the desalination of marine sand.
“Whether Hong Kong should consider adopting marine sand as a substitute for river sand, and how to exercise quality control on the desalination process itself, should be a topic for consideration,” the consultant said.
The construction industry has been aware of the potential for shortages of sand and substitutes have been proposed and tried out.
One such substitute for sand in concrete production was crushed rock fines.
CEDD statistics show that river sand used in concrete production plunged from 641,808 tonnes in 2008 to only 243,357 tonnes in 2012.
For the first five months of 2013, only 50,677 tonnes of river sand was imported for concrete production.
However using crushed rock fines in mortar mixes has been less successful due to poorer cohesiveness and workability.
To get round this, research has been carried out using manufactured sand.
Other options for substituting for river sand are use of proprietary tile adhesive systems in place of cement sand mortar, furnace bottom ash (FBA) from the burning of coal by electricity utility companies and recycling of waste glass.
In a research report earlier this spring, the Construction Industry Council called for further research into use of waste glass in the manufacture of mortar and low-strength concrete products.
In the end though the potential for a sand shortage may well be a blessing in disguise.
“In the long term, it may well be the case where this sand shortage drives innovation and efficiency in our industry,” Langdon & Seah said.