Bricks Made with Olive Pits Reduce Carbon Footprint of Buildings, Study Finds

A new study has shown that olive pit waste can effectively reduce energy usage in buildings, demonstrating how the circular economy can be applied to the construction sector.
By Simon Roots
Jul. 8, 2024 13:56 UTC

Spanish researchers from the University of La Rioja’s mechan­i­cal engi­neer­ing depart­ment use ground olive pits to pro­duce more energy-effi­cient build­ing mate­ri­als.

The researchers demon­strated that using ground olive pits in mor­tar brick man­u­fac­tur­ing can lead to sig­nif­i­cant eco­nomic sav­ings and reduce the envi­ron­men­tal impact of con­struc­tion and build­ing use.

The research ana­lyzed the impacts of dop­ing per­fo­rated mor­tar bricks with ground olive pits in a five to 15 per­cent ratio by vol­ume of fine aggre­gate for build­ing con­struc­tion.

The use of olive pit waste in the man­u­fac­ture of facade bricks is a clear exam­ple of how the cir­cu­lar econ­omy can trans­form an indus­try’s by-prod­ucts into inno­v­a­tive and sus­tain­able build­ing mate­ri­als.- Javier Ferreiro-Cabello, engi­neer­ing researcher, University of La Rioja

Doping is a tech­nique in which a small quan­tity of a sub­stance is added to a mate­r­ial to alter its prop­er­ties. The method is employed in the man­u­fac­ture of con­struc­tion mate­ri­als to increase their energy effi­ciency, strength, dura­bil­ity, fire resis­tance or cor­ro­sion resis­tance.

In recent years, more research has focused on dop­ing to reduce ther­mal con­duc­tiv­ity, which could lower the energy required to heat or cool build­ings.

Buildings are Europe’s sin­gle largest energy con­sumer. Approximately 40 per­cent of the total energy con­sumed in the European Union is used in build­ings, and around 80 per­cent of the energy used in E.U. homes is for heat­ing, cool­ing and hot water.

See Also:Researchers Transform Olive Grove Waste Into Bioplastic

Eighty-five per­cent of E.U. build­ings were built before 2000, and 75 per­cent have poor energy per­for­mance. The con­struc­tion sec­tor is, there­fore, seen as cru­cial to achiev­ing the E.U.‘s energy and cli­mate goals.

The study focused mainly on Andalusia, Spain, where large quan­ti­ties of olive pits are pro­duced as a by-prod­uct of olive oil pro­duc­tion.

My ini­tial inter­est arose from observ­ing the enor­mous vol­ume of waste gen­er­ated by the olive oil indus­try, specif­i­cally olive pits,” said lead author Javier Ferreiro-Cabello.

These residues have sig­nif­i­cant but under­uti­lized poten­tial in terms of reuse and added value,” he added. In study­ing pos­si­ble appli­ca­tions for these pits, I iden­ti­fied the pos­si­bil­ity of using them to man­u­fac­ture bricks for mor­tar facades. This idea led me to fur­ther inves­ti­gate the fea­si­bil­ity and envi­ron­men­tal impact of this pro­posal.”

The team’s analy­sis showed sav­ings and eco­nomic returns from the medium-term (10 to 20 years) onward by reduc­ing con­ven­tional energy con­sump­tion in heat­ing and air con­di­tion­ing instal­la­tions.

Previous research by Ferreiro et al. has demon­strated that dop­ing with ground olive pit con­cen­tra­tions of up to 30 per­cent can be used with­out com­pro­mis­ing struc­tural via­bil­ity. Concentrations above 15 per­cent were found to increase the eco­nomic recov­ery time beyond the aver­age use­ful life of a build­ing in Spain (70 years).

Several fac­tors were stud­ied to assess envi­ron­men­tal impact. These spanned the full life­cy­cle of the prod­uct, from olive pit grind­ing and its sub­se­quent trans­porta­tion to the pro­duc­tion and trans­porta­tion of doped mor­tar bricks.

When ana­lyz­ing the end pro­duc­t’s net impact over time, the resources used — energy, fuel and water — and the waste prod­ucts gen­er­ated — car­bon oxides, nitro­gen oxides and solid par­ti­cles — were con­sid­ered.

Increasing the per­cent­age of olive pits as a sub­sti­tute for fine aggre­gate was found to raise envi­ron­men­tal impacts in most cat­e­gories, except for water usage.

Higher olive pit con­tent low­ers the water impact because nat­ural aggre­gate pro­duc­tion requires sub­stan­tial water for inter­nal wash­ing processes.


A 15 per­cent dop­ing with olive pits resulted in a 7.98 per­cent reduc­tion in water con­sump­tion, sav­ing 0.61 cubic meters per square meter of the facade.

In the global warm­ing cat­e­gory, a 4.68 per­cent increase in CO2 emis­sions was cal­cu­lated for 15 per­cent dop­ing, equat­ing to 0.8 kilo­grams of CO2 per square meter of facade. This increase was due to the higher energy and resource con­sump­tion needed to incor­po­rate olive pits.

Categories related to nat­ural aggre­gate pro­duc­tion, includ­ing acid­i­fi­ca­tion, eutroph­i­ca­tion, and pho­to­chem­i­cal oxi­da­tion, saw increases of 29.13 per­cent, 30.28 per­cent, and 21.56 per­cent, respec­tively. The olive pit prepa­ra­tion process, involv­ing energy and mate­r­ial use for crush­ing and trans­port, caused these impacts.

See Also:Olive Milling Byproducts May Improve Animal Feed

Transport processes were found to sig­nif­i­cantly affect recy­cled aggre­gates’ via­bil­ity, increas­ing nitro­gen oxides, car­bon oxides and solid par­ti­cles that impact the ozone layer.

A 15 per­cent dop­ing showed an 8.90 per­cent increase in ozone layer deple­tion and an 8.19 per­cent rise in fos­sil fuel deple­tion, equiv­a­lent to 6.90 mega­joules per square meter of facade.

When cal­cu­lated over a 35-year period, how­ever, the increases in energy use and emis­sions asso­ci­ated with the ini­tial man­u­fac­tur­ing process were more than off­set by the over­all sav­ings.

The analy­sis showed that over this period, the net energy cost of 15 per­cent-doped mate­r­ial man­u­fac­ture was below zero, and the CO2 emis­sions were also below zero for all build­ing energy sources. This lat­ter was most remark­able for build­ings using elec­tri­cal power sources, with a reduc­tion of 105.84 per­cent.

However, the authors stress that the ben­e­fits of olive-pit dop­ing are lim­ited to regions where olive waste is abun­dant and local, as trans­port is a sig­nif­i­cant con­trib­u­tor to energy usage and emis­sions. Thus, increased trans­port would result in sig­nif­i­cantly fewer ben­e­fits.

They also note that this is only one of many exam­ples of the indus­try’s poten­tial for increased sus­tain­abil­ity.

The cir­cu­lar econ­omy will play a key role in the future of con­struc­tion by offer­ing sus­tain­able and effi­cient solu­tions to address envi­ron­men­tal and eco­nomic chal­lenges,” Ferreiro said. By adopt­ing prin­ci­ples of reuse, recy­cling and waste reduc­tion, the con­struc­tion indus­try can min­i­mize its envi­ron­men­tal impact and max­i­mize resource use.”

In the spe­cific con­text of my research, the use of olive pit waste in the man­u­fac­ture of facade bricks is a clear exam­ple of how the cir­cu­lar econ­omy can trans­form an indus­try’s by-prod­ucts into inno­v­a­tive and sus­tain­able build­ing mate­ri­als,” he added.

Many ini­tia­tives to increase sus­tain­abil­ity in the build­ings and con­struc­tion sec­tors are in place world­wide.

These range from multi­na­tional pro­grams such as the United Nations’ Sustainable Development Goal 12 and the European Union’s Strategy for Sustainability in Construction and Renovation Wave pro­grams to leg­is­la­tion at national and local lev­els.

However, Ferreiro believes that much more can be done.

The gov­ern­ment can play a cru­cial role in encour­ag­ing research and devel­op­ment in the field of sus­tain­able con­struc­tion through sup­port­ive poli­cies and pro­grams,” he said. This could include finan­cial incen­tives for com­pa­nies invest­ing in research and devel­op­ment projects related to the cir­cu­lar econ­omy and sus­tain­abil­ity in con­struc­tion.”

In addi­tion, the gov­ern­ment could estab­lish reg­u­la­tions and stan­dards that pro­mote the use of recy­cled mate­ri­als and the adop­tion of sus­tain­able prac­tices in the con­struc­tion indus­try,” Ferreiro con­cluded. Education and aware­ness pro­grams could also help sen­si­tize key stake­hold­ers to the impor­tance of sus­tain­abil­ity and the cir­cu­lar econ­omy in con­struc­tion.”


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