SUNDAY, SEPTEMBER 23, 1990
PFA IN CONCRETE SAVES MONEY AND IMPROVES ENVIRONMENT
IN
IT,
AND THE
IF ALL CONCRETE WERE TO HAVE PULVERISED-FUEL ASH (PFA) HONG KONG COULD SAVE $300 MILLION A YEAR IN FOREIGN EXCHANGE ENVIRONMENTAL PROBLEMS ASSOCIATED WITH DISPOSING OF THE ASH WOULD DISAPPEAR.
PFA
THE DEPUTY SECRETARY, WORKS BRANCH OF THE GOVERNMENT
SAID TODAY (SUNDAY): "MOREOVER, SECRETARIAT, MR DICK PILLING, CONCRETE IS TECHNICALLY SUPERIOR TO ORDINARY CONCRETE."
FOR
NOTES
IN AN EFFORT TO ENCOURAGE THE WIDER USE OF PFA IN CONCRETE, THE WORKS BRANCH HAS ISSUED A TECHNICAL CIRCULAR AND GUIDELINES ITS USE, AND THE BUILDINGS ORDINANCE OFFICE HAS ISSUED PRACTICE FOR AUTHORISED PERSONS AND REGISTERED CONTRACTORS STATING HOW BE USED IN PRIVATE SECTOR BUILDINGS.
IT CAN
OF THE WORKS BRANCH ON
"THESE INITIATIVES HAVE THE SUPPORT
PLANNING, ENVIRONMENT TECHNICAL GROUNDS, THE
AND LANDS ENVIRONMENTAL GROUNDS AND THE FINANCE BRANCH FOR ECONOMIC MR PILLING SAID.
BRANCH ON REASONS,"
"AT PRESENT HONG KONG IS USING ABOUT FOUR MILLION TONNES OF CEMENT PER YEAR. SOME IS IMPORTED AS CEMENT, SOME AS CLINKER WHICH IS GROUND INTO CEMENT IN HONG KONG.
ABOUT
"THE AVERAGE COST OF THE IMPORTED MATERIAL IN 1989 WAS
IF A QUARTER OF THIS WAS $300 PER TONNE.
REPLACED BY PFA, THERE WOULD BE SUBSTANTIAL SAVINGS IN FOREIGN EXCHANGE.
PFA IS THE FINE ASH PRODUCED WHEN PULVERISED COAL IS THE POWER STATIONS AT TAP SHEK KOK AND LAMMA ISLAND. ABOUT ONE MILLION TONNES IS PRODUCED ANNUALLY AND THE POWER COMPANIES SPEND MILLIONS OF DOLLARS DISPOSING OF IT AS A WASTE MATERIAL.
BURNT
IN
BUT, IF IT IS TREATED ΤΟ REMOVE THE LARGE PARTICLES AND BECOMES A UNBURNT CARBON, A PROCESS KNOWN AS CLASSIFICATION, THE ASH USEFUL MATERIAL WITH
PROPERTIES WHICH CAN BE USED IN
CONCRETE.
POZZOLANIC
MR PILLING SAID: "WHEN CEMENT REACTS WITH WATER IT RELEASES
SETS LIKE LIME, AND THE LIME REACTS WITH THE PFA WHICH THEN
CEMENT. REPLACING ABOUT 25 PER CENT OF THE CEMENT IN CONCRETE WITH PFA HAS MANY BENEFITS.
"CONCRETE MADE WITH CEMENT DOES NOT GET MUCH STRONGER AFTER
USED THE CONCRETE CONTINUES ABOUT A MONTH, BUT IF PFA IS
ΤΟ GAIN
STRENGTH FOR UP TO A YEAR OR MORE.
IT
"PFA HAS OTHER USEFUL PROPERTIES SUCH AS REDUCING THR HEAT
LEADS GENERATED WHEN THE CONCRETE SETS WHICH OFTEN
TO CRACKING. IS EASIER TO COMPACT AND PRODUCES A BETTER FINISH THAN ORDINARY CONCRETE, HE SAID.
/ALTHOUGH PFA