Silt can be made into a good housing material

MANILA, Philippines - Though Metro Manila is still baking under the sun, weather experts are warning the public that the La Niña weather phenomenon, which brings torrents of rain, will start in July.

The flash floods caused by typhoon “Ondoy” on Sept. 26, 2009 are still fresh in the minds of those who survived the deluge.

Inventor Emmanuel Alkuino said these flash floods could repeat themselves unless the dams and waterways are desilted, and the silt prevented from trickling back into the water.

“We allowed our dams and waterways to fill with silt. That is why our dams and waterways fill up with water so quickly. What water can they contain when they’re filled with mud?” he told The STAR following a recent investor’s fair organized by the Philippine Council for Industry and Energy Research and Development of the Department of Science and Technology (DOST).

Alkuino said dredging has always been very costly because one would need the right machine and a suitable dump.

“This dump will have to be strategically located so that possible ‘back-flow’ of this mud back to the waterways where it was extracted is eliminated,” he said.

Alkuino, who is the president and chief executive officer of family-run firm Sidlakpinoy, Inc., is proposing that the silt dredged from the waterways in and around Metro Manila be used to produce what he calls “reinforced fire bricks,” an invention he patented in 2004.

He said these bricks are baked with alluvial silt and either rice hull ash or fly ash (a by-product of coal-fired boilers), which make them five times stronger than ordinary concrete hollow blocks, according to compressive strength tests.

Alkuino said his bricks are currently used by developers and homeowners in his native Bukidnon as well as in Cagayan de Oro, Davao City and North Cotabato.

Among the non-government organizations that use these bricks for their low-cost housing projects in Mindanao are the Gawad Kalinga Bukidnon and the Habitat for Humanity Butuan, he added.

He sells the bricks at a profit of P6 each, compared to hollow blocks that cost at least P9. Alkuino said since there is no need to fill in the holes in the brick with cement – the holes serve as a locking mechanism to prevent the bricks from slipping – the bricks reduced cement usage by as much as 50 percent and total construction cost by as much as 40 percent.

Alkuino, 62, said he has been researching the possible uses of alluvial silt since 1974. Using silt and silica from rice hull ash and fly ash, he designed both the formula and the machine to produce the bricks.           

In 1998, the DOST extended financial and technical assistance to Alkuino to improve the quality of his bricks and the efficiency of his machines. Today, his brick-making machines can produce from 5,000 to 15,000 bricks per day.

He sells his brick-making machine for P5 million, including the transfer of technology.

Alkuino proposed that a synchronized dredging and brick-making process be established around the areas around Laguna Bay, and the Pasig and Marikina Rivers, with the rice hull sourced from rice-producing areas around Metro Manila.

“The rice hull will be used as fuel to (bake) the bricks, and rice hull disposal around Metro Manila should be monitored to ensure a steady source of fuel,” he said.

Existing brick factories may be retooled to produce his fire bricks, and crash courses in brick-laying will have to be conducted to ensure that the bricks are laid properly, according to Alkuino.

He said unlike cement hollow blocks, his bricks should be immersed in water for 10 to 15 minutes until they are fully saturated.

“Never lay bricks that are still dry. The bond between the brick and the cement will be weak, resulting in an inferior masonry,” Alkuino said.

He also said there is no need to paint the bricks. He said bricks can be dyed and then finished with sanding sealer, polyurethane, varnish or concrete emulsion for interiors.

For outside walls and fences, Alkuino recommends applying used automotive oil to prevent the growth of fungi and moss. “The used oil will deepen the (hue) of the bricks, not make them black,” he said.