Study: Asphalt Made with Olive Pomace More Resilient to Weathering

The right amount of olive pomace incor­po­rated into asphalt binder could dra­mat­i­cally enhance the resilience of paving mate­ri­als to crack­ing and other forms of weath­er­ing, a new study found.

The research con­firmed the results of pre­vi­ous stud­ies and explored the pro­duc­tion process of a new kind of par­tially sus­tain­able asphalt.

The study, led by Kun Zhang at the California State University, found that olive pomace could improve the asphalt binder’s resis­tance to events such as oxi­da­tion-induced crack­ing, fatigue crack­ing and crack­ing due to low-tem­per­a­ture events.

In addi­tion, the mod­i­fied binder also com­pared favor­ably to the tra­di­tional asphalt binder when it comes to rut­ting resis­tance.

Olive pomace is the main byprod­uct of olive oil pro­duc­tion and con­tains cel­lu­lose, hemi­cel­lu­loses, lignin, uronic acids, phe­no­lic com­pounds and oily residues.

The mas­sive amount of olive pomace pro­duced by olive oil pro­cess­ing con­sti­tutes an envi­ron­men­tal chal­lenge due to its poten­tial to pol­lute and the costs asso­ci­ated with its dis­posal.

The research, which was funded by the Olive Oil Commission of California (OOCC), showed that olive pomace pulp-rich frac­tion could be pre­cisely sep­a­rated from the stone-rich frac­tion to obtain its opti­mal level of antiox­i­dant qual­i­ties.

By apply­ing this dried olive pomace to the asphalt binder, sci­en­tists found that it mod­i­fied the mate­r­ial with bet­ter soft­en­ing and antiox­i­dant effec­tive­ness, vastly improv­ing its final per­for­mance. They also reported that adding up to five per­cent of the pulp-rich frac­tion would neu­tral­ize the oxi­da­tion caused by asphalt mix­ing and pro­duc­tion.

“The use of a higher dosage of pulp-rich frac­tion – e.g., 15 per­cent and 25 per­cent – could sig­nif­i­cantly extend the ser­vice life of mod­i­fied asphalt binders prior to expe­ri­enc­ing ini­tial and severe oxi­da­tion-induced crack­ing,” the researchers wrote. ​“The pomace-mod­i­fied asphalt mix exhib­ited bet­ter crack­ing resis­tance after long-term aging than the con­trol mix.”

The new research con­tributed to the OOCC’s ongo­ing inves­ti­ga­tions on ways to cur­tail the poten­tially pol­lut­ing effect of waste gen­er­ated by olive oil pro­cess­ing on soil and ground­wa­ter.

In a press release, the OOCC empha­sized that ​“future work on this project will focus on the chem­i­cal com­po­si­tion in the processed olive pomace and iden­tify active ingre­di­ents that could fur­ther extend the life of asphalt pave­ments.”

According to the study’s authors, the use of the new asphalt binders would pro­mote sus­tain­abil­ity in both agri­cul­ture and asphalt paving indus­tries.

They also stressed the need ​“to inves­ti­gate active ingre­di­ents in olive pomace to max­i­mize antiox­i­dant capac­ity and develop zero-waste recy­cling meth­ods to uti­lize waste­water in olive pomace.”

“Study authors are now seek­ing funds for addi­tional research through the 2021 Agriculture and Food Research Initiative,” the OOCC added, con­clud­ing that it has already sub­mit­ted a let­ter of sup­port for this project, ​“to encour­age valu­able and prac­ti­cal uses for byprod­ucts from olive oil pro­cess­ing.”

• Olive Oil Commission of California
• Olive Oil Commission of California
• Conference on Civil Engineering Architecture & Urban Sustainable Development