Il calcestruzzo stampato in 3D può salvare l’ambiente?

Il calcestruzzo è sempre presente intorno a noi. Dalle case, uffici e edifici scolastici ai negozi, dighe, ponti, marciapiedi e strade, il calcestruzzo aiuta a costruire le strutture che usiamo ogni giorno. 

Non è affatto un materiale nuovo. Infatti, la prima registrazione di strutture in calcestruzzo risale al 6500 a.C. nelle regioni della Siria e della Giordania. Poi, naturalmente, ci sono i Romani che hanno fatto ampio uso del calcestruzzo nelle loro costruzioni. E ora, eoni dopo, molte di queste strutture sono ancora in piedi oggi.

Negli anni, l’uso del calcestruzzo è solo aumentato, con il mercato globale del calcestruzzo che si attestava a $687.2 billion nel 2021. Si prevede inoltre che crescerà fino a $821.6 billion entro il 2026, dimostrando il ruolo che il calcestruzzo svolge nelle nostre vite. 

Questa espansione è guidata dalla crescita dell’industria delle costruzioni così come dall’aumento degli investimenti in nuovi progetti di costruzione in tutto il mondo. La crescita economica e l’urbanizzazione rapida contribuiscono anche alla crescente domanda di complessi residenziali e commerciali a livello globale. Man mano che le città crescono, cresce anche la necessità di infrastrutture e, con esse, la necessità di calcestruzzo.

Anche se sappiamo che la domanda di cemento è costante da secoli, perché è così popolare in primo luogo? E tutto è positivo? Bene, scopriamolo!

Calcestruzzo: la necessità pericolosa del mondo

Prima di capire cosa rende il calcestruzzo così prezioso, vediamo cos’è esattamente. È una miscela di cemento (o calce), acqua e aggregati, che sono un insieme di particelle naturali o artificiali come sabbia, ghiaia o roccia frantumata. 

Qui, il cemento, che è una miscela prodotta di calcio, ferro, silicio e alluminio, tra gli altri ingredienti, è il materiale legante che conferisce al calcestruzzo le proprietà di indurimento, mentre l’acqua attiva il cemento per formare un materiale denso. 

Ciò che rende questo materiale composito così prezioso sono le sue proprietà, inclusa la malleabilità — la capacità del calcestruzzo appena mescolato di essere modellato in quasi qualsiasi forma — e la durabilità, cioè la capacità di durare per molti anni. Questo materiale conveniente può inoltre essere personalizzato per soddisfare diverse esigenze di costruzione.

Altre proprietà attraenti del calcestruzzo includono la facilità d’uso, la resistenza e la capacità di sopportare non solo carichi pesanti e stress compressivi, ma anche condizioni meteorologiche avverse e disastri naturali come terremoti e uragani.

Inoltre, il calcestruzzo ha la capacità di trattenere il calore, è ignifugo e facile da riparare in caso di danni. Tutte queste proprietà rendono il cemento un prodotto altamente prezioso, facendo schizzare all’impazzita il suo utilizzo.

Per quanto riguarda i casi d’uso del calcestruzzo, ha varie applicazioni nell’industria delle costruzioni. Il calcestruzzo è in realtà il materiale da costruzione più utilizzato al mondo dopo l’acqua. Viene impiegato per costruire dighe, ponti, autostrade, aeroporti, strade, canali, serbatoi e pavimentazioni, insieme a edifici residenziali, complessi commerciali e altre strutture portanti.

In parole semplici, il calcestruzzo è un materiale fondamentale nella costruzione, svolgendo un ruolo cruciale nella formazione delle infrastrutture intorno a noi. 

Tuttavia, ciò non significa che il calcestruzzo offra solo benefici. In realtà, è estremamente pericoloso. 

Per cominciare, il cemento è responsabile di 1.6 billion metric tonnes di anidride carbonica (CO2), che rappresentano circa l’8% delle emissioni globali di CO2. E la dipendenza estesa del settore delle costruzioni dal cemento aggrava la sua enorme impronta di carbonio.

Nel frattempo, la produzione di cemento Portland ordinario (OPC) è responsabile del 5% all’8% delle emissioni globali di CO2 antropogeniche. Quando si estende a tutte le attività legate alle costruzioni, l’ultimo research mostra un quadro allarmante, con quasi il 40% delle emissioni di CO2 legate all’energia provenienti da questo settore, che consuma il 36% dell’energia finale mondiale.

Questo è estremamente preoccupante perché le emissioni di CO2 sono previste raggiungere un record di 37.41 GtCO2. Le emissioni di CO2 sono anche la causa principale del riscaldamento globale e, secondo l’IPCC, il riscaldamento globale al ritmo attuale è previsto raggiungere 1.5 °C sopra i livelli preindustriali tra il 2030 e il 2052.

Considerate le ripercussioni ambientali del calcestruzzo, mentre il suo tasso di consumo annuale ammonta a 30 miliardi di tonnellate e si prevede che continui a crescere, è importante che tutti, dagli innovatori alle organizzazioni e ai governi, affrontino questo problema direttamente.

Advancing Construction with 3D Printing 

Il calcestruzzo, come abbiamo notato sopra, è un male necessario perché, sebbene offra grandi benefici e sia cruciale per la civiltà, è davvero dannoso per il pianeta, che già affronta deforestazione, cambiamento climatico, perdita di biodiversità e molto altro. 

Aggiungi il calcestruzzo al mix e le cose peggioreranno semplicemente. Ma se ci fosse un modo per affrontare gli effetti nocivi di questo popolare materiale da costruzione? 

Bene, innanzitutto, il calcestruzzo sta evolvendo per soddisfare le esigenze complesse e avanzate del mondo. Come abbiamo condiviso in precedenza, materiali avanzati come il grafene e la canapa vengono sempre più utilizzati nei materiali da costruzione. Anche il cemento privo di carbonio viene prodotto sostituendo la pietra calcarea o utilizzando pietra calcarea derivata da combustibili fossili.

C’è un’altra soluzione, ed è la stampa 3D. Esatto! Lo stesso metodo che viene utilizzato per creare arte, mobili e altri prodotti di consumo, insieme a forense, protesi e chirurgia, sta anche cambiando il gioco per la costruzione. 

La stampa 3D o manifattura additiva, che consiste nel creare oggetti tridimensionali da un file digitale depositando strati di materiale, ha guadagnato molta trazione grazie ai suoi vantaggi di prototipazione rapida, personalizzazione, risparmio sui costi, riduzione degli sprechi di materiale, promozione dell’innovazione e sostenibilità. 

Questa tecnologia è ora being utilized in construction, which isn’t anything new in itself, as 3D printing was first used in construction many decades ago. However, the use of 3D printing has grown significantly in recent years to accelerate the process significantly, optimize material usage, explore intricate designs and tailored structures, facilitate remote construction, and enhance safety.

The multifaceted benefits of 3D printing further include shorter supply chains due to on-site construction and a substantial decrease in workplace hazards due to reduced need for manual labor in high-risk operations.

This year, we actually saw the world’s largest 3D-printed neighborhood in Texas near its completion after being two years into construction. 3D-printed construction company ICON is behind this project.

A private company, ICON not only prints residential homes but is also involved in defense and off-world construction. Less than a decade ago, ICON raised a total of $451 million, which has increased its valuation to about $2 billion. The company is actually contracted by NASA to build landing pads, shelters, and other structures on the Moon as part of the agency’s Artemis Moon exploration program.

In 2018, it built the first permitted 350-square-foot 3D-printed home in the U.S., which only took two days. The house was built using concrete because, as ICO CEO Jason Ballard stated:

“It’s one of the most resilient materials on Earth.”

For its Texas community, the company is using its Vulcan printer, which is much like a regular desktop 3D printer, and pipes layer by layer. The difference with this Vulcan printer is that it is 45 feet wide and weighs 4.75 tons. 

As for its process, concrete powder is mixed with sand, water, and other additives and then pumped into the printer. The concrete mixture is then squeezed out by a nozzle onto a brush, which builds up layer by layer following a pre-programmed path.

The robotic printer has built 100 3D-printed houses in what it says is the world’s largest 3D-printed community. With 3D printing being faster, less expensive, minimizing construction material waste, and requiring fewer workers, it is bringing “a lot of efficiency to the trade market,” as per the company.

This is just the beginning, though, as evident from the growth the 3D printing construction market is expected to see. Valued at $5.5 billion last year, the global 3D printing construction market is projected to grow at a CAGR of 105.8% to reach a whopping $3.3 trillion by 2032. 

These numbers may seem mind-boggling at first, but as we shared in our previous article, 3D printing could emerge as a potential solution to the grievous problem of housing shortage, which makes the trillion-dollar target a real possibility.

Given the tremendous interest in 3D printing construction, it also makes sense to utilize this technology to change the construction market for the better. And that’s exactly what scientists from Nanyang Technological University (NTU) of Singapore are doing.

The researchers went yet another step further or deeper by 3D printing the concrete itself. For this, they have developed a 3D concrete printing method that captures carbon, showcasing a new way to reduce the environmental impact of the construction industry.

Click here to learn if 3D printing can help us tackle housing shortage.

3D Printing Concrete that Captures CO2

Earlier this month, NTU scientists published their research on “Carbon capture and sequestration with in-situ CO2 and steam-integrated 3D concrete printing.”

The research detailed the innovative method that aims to reduce the carbon footprint of cement significantly by cutting down the material usage, labor requirements, and construction time. 

It is also suggested that sustainable development through 3D concrete printing may add as much as 5% reductions in global energy usage. These environmental benefits are potentially equal to its ability to streamline construction processes. 

However, mixing CO2 in concrete, as the latest study does, has been done before with an aim to improve the quality of the material and help bring down cement’s negative environmental impact.

Early studies have already shown improvements in the mechanical properties of concrete through direct batch mixing with CO2 and exposing concrete to CO2 during production in carbonation chambers due to forming a “carbonation shell.” 

Previous studies have reported an almost 15x increase in penetration resistance and as much as 1.16% carbon absorption in just half an hour of mixing mortar with CO2. Adjusting the accelerated carbonation curing (ACC) further showed a 1.98–25.5% carbon absorption.

While research on 3D concrete printing has largely focused on designing green cementitious mixtures to reduce its carbon footprint, the latest study noted that a few have considered advancing processing technologies, particularly to enhance its bulk carbon capture and storage capacity (CCS). 

Studies on the carbonation of cementitious materials, particularly the minimal focus on depths, the researchers noted, are why their scaled implementation raises validity concerns. Not to mention, chamber-confined CCS solutions face limitations in terms of hardware and energy consumption when applied with 3DCP. As a result, the benefits of scalable, automated, and on-site construction are compromised.

This creates a need to develop an artificial carbonation process for 3D concrete printing that goes beyond traditional curing techniques.

As a result, the NTU researchers developed a new process to study its efficacy at sequestering carbon dioxide.

The newly developed technology involves a two-step extrusion-based system. The first step is injecting CO2 and steam into the mixing concrete. The mixture then directly incorporates and stores the CO2 in the concrete structure. The CO2 and steam in question are captured as the by-products of industrial processes. 

This new approach demonstrated an increase of 38.2% in bulk carbon uptake, offering yet another way to achieve decarbonized construction by 3D printing concrete.

The design of the proprietary printhead attachment, which facilitates the regulated injection of gaseous and liquid additives, seeks to tackle the critical issue of environmental sustainability concerns with automated construction. It also addresses the issue of set-on-demand requirements but, most importantly, a lack of readily available CCS solutions that are compatible with 3D concrete printing.

Not only does the new way reduce cement’s carbon footprint, but it has also been shown to improve the mechanical properties of the concrete. This, in turn, offers great strength to the structure in comparison to traditional 3D-printed concrete.

According to the research paper, the CO2 and steam integration resulted in an increase of up to 50% in 3D printability, 45.3% in flexural strength, and 36.8% in compressive strength. 

The researchers concluded that the samples that were exposed to CO2-steam integrated printing and open-air curing got the highest carbon uptake. According to the researchers:

“The presented solution offers a promising pathway towards decarbonized construction while expanding viable options for CCS beyond traditional confined curing methods.”

The team further pointed out the optimization of printing configurations, mix designs, and the injection of flue gases to reduce pure carbon dioxide feedstock wastage as possible areas for future research.

Investable Company in 3D Printing Space

Now, let’s take a look at a publicly traded company involved in the 3D printing market, which is estimated to be worth $17.5 billion in 2024 and is projected to grow at a CAGR of 16.4% to $37.4 billion in the next five years, that’s making advances in the sector and helping change the world for the better.

1. Stratasys Ltd.

Stratasys is a popular name in the 3D printing space, and it provides solutions across multiple sectors. Technologies from the company have been contributing to advancements in the 3D printing field. 

With a market cap of $689.5 million market cap, Stratasys has its shares currently trading at $9.66, down 32.35% this year. The company has an EPS (TTM) of -1.32 and a P/E (TTM) of -7.30.

For Q3 of 2024, Stratasys reported revenue of $140.0 million, up from $162.1 million recorded in the same quarter last year. With these numbers, the company’s recurring consumables revenue has been seeing year-over-year growth for eight straight quarters now, which it stated “reflects continued strong printer utilization.”

The growth of the GAAP gross margin of Stratasys improved to 44.8%, while its GAAP net loss came in at $26.6 million, and non-GAAP net income started to achieve profitability. $4.5 million of cash was reported to be used in operations, and YTD’s operating cash flow remains positive.

With these strong numbers, Stratasys raised its outlook for the full year 2024. As per that; it reported $580 mln in revenue of $570 million, Non-GAAP net income of $5 million, and capital expenditures of $20 million.

“We have successfully begun to transform the company through cost optimization and by focusing on higher-growth opportunities.”

– CEO Dr. Yoav Zeif said at the time

He further noted that the company’s main F3300 platform is getting a lot of attention while it continues to expand into its main target sectors, including healthcare, automotive, and aerospace.

According to Dr. Zeif, the company’s restructuring plan will help deliver $40 million in annual cost savings from next year.

“We are well-positioned to deliver increased revenue growth, profitability and cash flow in 2025, to address the pent-up demand once market conditions improve.”

– Dr. Zeif

Click here to learn all about investing in Stratasys Ltd. (SSYS )

Conclusion

Concrete has been a cornerstone of human development for centuries, but it is not without its dangers. The environmental impact of concrete is becoming a grave concern, creating an urgent need to find better solutions. The latest technology from NTU researchers is one such development that is going in the right direction. By utilizing additive manufacturing principles, 3D concrete printing has redefined traditional operations and promoted sustainability. 

As the world struggles with urban expansion and climate change, innovations like 3D concrete printing can help the world meet the growing and complex needs of construction while mitigating its harmful effects. And though challenges remain in scaling and standardization, over time, as technology improves and gets widely adopted, 3D printing can play a key role in shaping tomorrow’s infrastructure.

Click here for a list of top additive manufacturing and 3d printing stocks.