` Olive Stones 'Ideal' for Noise Barriers - Olive Oil Times

Olive Stones 'Ideal' for Noise Barriers

Feb. 10, 2013
Julie Butler

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Scientists in Valencia have devel­oped a new use for left­over olive stones — in sound bar­ri­ers such as those used to reduce rail and road noise.

They found the poros­ity of olive stones — charred ones in par­tic­u­lar — gives them high absorp­tion ability.

The Panolston project researchers, from the Polytechnic University of Valencia’s (UPV) Institute of Transport and Territory, together with the pre­fab­ri­ca­tion com­pany Precon, claim porous con­crete acoustic screens made with car­bonized olive stones are a viable alter­na­tive to cur­rent options.

Civil engi­neer and UPV researcher Julia Real said they not only mit­i­gate rail and road noise, they pro­vide a new out­let and value-adding for an agri­cul­tural by-prod­uct, olive stones.”

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We have com­pared their acoustic per­for­mance to screens made with con­ven­tional porous con­crete, and also with wood or min­eral wool with per­fo­rated sheet metal, and their absorp­tion capac­ity is highly com­pet­i­tive, ” she said.

Screens made with min­eral wool are one of the best options cur­rently on the mar­ket but they are expen­sive, cost­ing €90 – 120/m2, and work more by reflect­ing than absorb­ing noise. Wood screens are now largely obso­lete, she said.

Our screens of porous con­crete and charred olive stones not only reflect noise, they absorb it, and with very high lev­els of absorp­tion. Furthermore, they don’t burn because the stones have already been burned, and they’re 18 per­cent cheaper.”

Depending on the pro­por­tion of olive stone char used and a screen’s sur­face fin­ish, dif­fer­ent fre­quen­cies can be absorbed. This allows adapt­abil­ity to dif­fer­ent kinds of noise, such as from a high­way or high-speed rail­way, she said.

Fellow UPV researcher Laura Montalban Domingo told Olive Oil Times that charred olive stones have a high level of poros­ity. The open poros­ity allows a sound wave to pen­e­trate the mate­r­ial and dis­si­pate as it crashes’ into the inte­rior walls of a pore, while the closed poros­ity mod­i­fies the den­sity and rigid­ity of the mate­r­ial, mod­i­fy­ing the screen’s vibra­tional response,” she said.

According to a ScienceDaily report on mak­ing bioethanol from olive stones, Spain’s olive oil and table olive sec­tors together gen­er­ate about 4 mil­lion tons of olive stone waste a year. Its main use has so far been for energy gen­er­a­tion in bio­mass boilers.

Meanwhile, accord­ing to the Tea Obsession blog, olive stone char­coal is part of the ancient tea cul­ture of Chao Zhou, China, where it is used to both boil and fla­vor the water.

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