Vibing Masonry #2: Masonry for Sustainability & Energy Saving

Words: Steve Blye

Welcome to the second installment of our “Vibing Masonry” series on the benefits and functionality of masonry in modern construction, with a focus on its environmental and sustainability advantages.



The Environmental Case for Masonry
Masonry is a sustainable option due to its reliance on natural materials, reducing dependence on synthetic substances. For example, clay bricks are composed of abundant, non-toxic materials sourced regionally. Civic buildings have historically utilized natural stone, demonstrating a commitment to durability and the community. Concrete masonry units (CMUs) are made from lime cement and aggregates, offering sustainable solutions for walls and structures. Cast stone and manufactured stone can replace natural stone, providing budget flexibility, while terra cotta, often glazed, delivers durable, intricate finishes.



Key Benefits of Masonry
1. Durability and Longevity: Masonry’s lifespan often exceeds 100 years, significantly reducing replacement frequency, conserving resources, and minimizing waste.

2. Resilience: Masonry structures withstand extreme weather conditions, including wind and rain, reducing the need for costly repairs and offering long-term reliability.

3. Adaptability: Masonry's flexibility allows buildings to be easily repurposed, extending their use and minimizing the need for new materials.

4. Low Maintenance: Masonry structures require minimal upkeep, saving time and resources, and reducing the need for additional materials and treatments.

Masonry: Built to Withstand Weather, Climate, and Energy Loss
Masonry is renowned for its durability and resistance to extreme weather, making it ideal for long-lasting structures. Whether facing high winds, heavy rain, or UV exposure, masonry remains resilient, reducing the need for frequent repairs while maintaining its appearance. Masonry walls also stabilize indoor environments by buffering against external conditions. Their resistance to wind-driven rain, snow, and high-velocity winds makes them suitable for both urban and rural applications.

Another environmental advantage is the reduction of the Heat Island Effect. Masonry reflects sunlight and absorbs less heat, helping mitigate the urban heat island effect, which is crucial in densely built environments. Additionally, masonry excels in Water Management. Permeable concrete masonry pavers manage stormwater runoff, alleviating pressure on local water systems, which is essential for sustainable urban development.

Masonry’s Sustainability and Energy Efficiency
Masonry is inherently sustainable, incorporating insulation, air barriers, and vapor retarders to reduce energy loss and improve thermal efficiency. The concept of embodied carbon—the emissions associated with material production, transportation, and disposal—highlights masonry’s role in sustainable building. Concrete masonry units (CMUs) contribute to carbon sequestration, absorbing CO₂ over time, making them integral to low-carbon strategies. Furthermore, masonry materials emit low levels of VOCs, promoting healthier indoor air quality in sustainable designs.



Recycled and Sustainably Manufactured Materials
Masonry is renowned for its durability and resource efficiency. Materials like natural stone require significantly less energy to produce compared to synthetic alternatives, thereby lowering embodied energy and carbon emissions. Furthermore, masonry materials—such as stone, brick, and concrete masonry units (CMUs)—can be recycled or repurposed in new construction, which reduces the demand for new raw materials. By grinding old clay bricks, cement, and CMUs into aggregates, these materials can be reused in new CMU blocks, effectively reducing construction waste and environmental impact. This adaptability and reusability position masonry as a key material in sustainable construction.



Economic and Environmental Benefits
Masonry is cost-effective due to the local sourcing of materials like bricks and concrete masonry units (CMUs). Locally sourced materials reduce transportation emissions and bolster local economies. Masonry’s inherent longevity and resistance to fire, storms, and climate impacts contribute to lower insurance premiums, offering both financial savings and environmental benefits.

Energy Efficiency and Indoor Comfort
Masonry excels in energy efficiency by utilizing its thermal mass to stabilize indoor temperatures, which reduces the need for heating and cooling. This results in lower energy bills. Optimizing the Window-Wall Ratio (WWR) in masonry structures is crucial for enhancing energy performance by balancing natural light and thermal efficiency. Masonry's compatibility with various insulation systems, such as spray foam, rigid foam board, and mineral wool, helps minimize thermal bridging and creates seamless thermal barriers, thereby improving thermal performance and maintaining structural integrity.



Innovative Systems for Enhanced Thermal Resistance
Advanced systems like Insultech Block and Omni Block integrate rigid foam inserts between CMUs and interior blocks, optimizing both thermal resistance and structural performance. Foamed-in-place insulation, including cementitious or resin foams, fills the hollow cores of masonry units, enhancing thermal properties and improving air-sealing efficiency, ensuring a highly efficient building envelope.

Masonry's Fire Resistance
Masonry materials are non-combustible and offer exceptional fire resistance, with walls achieving fire ratings of 2 to 4 hours. This critical property helps protect structures and occupants, as masonry does not contribute to fire spread. For instance, steel structures may fail during a fire, but masonry walls often remain intact, preserving the building's structural integrity.





Acoustic, Health, and Pest Resistance Benefits
In addition to fire protection, masonry provides excellent sound insulation, with high Sound Transmission Class (STC) ratings that reduce noise pollution and enhance acoustic comfort, particularly in environments such as theaters. Masonry's natural properties also reduce the risk of mold, mildew, and pests like termites, eliminating the need for harmful chemical treatments and enhancing both the building's durability and its environmental sustainability.



Innovations in Wall Design
Masonry utilizes its thermal mass to regulate internal temperatures, thereby enhancing energy efficiency and indoor comfort. The inherent air spaces within masonry construction allow for effective moisture drainage, reducing condensation risks and improving indoor air quality. Modern masonry assemblies are designed to reduce thermal bridging while maintaining necessary vapor permeability, ensuring effective heat transfer management and water resistance. Features such as through-wall flashing provide additional protection against water infiltration, enhancing the overall performance and longevity of the building envelope.

Furthermore, masonry materials are often sourced locally, which supports regional economies and reduces transportation emissions. Masonry’s excellent fire resistance can lead to lower insurance premiums, enhancing cost-effectiveness. Its insulating properties and structural integrity make masonry an ideal choice for energy-efficient mid-rise buildings that combine safety with long-term energy savings and cost-effectiveness.

CMU Concrete Additives to Enhance Performance
1. Fly Ash and Slag Cement-- These materials are by-products of coal combustion and steel production, respectively. When used as partial replacements for Portland cement, they improve workability and long-term strength while reducing the overall carbon footprint of concrete production.

2. Structural Grade Ceramic Lightweight Aggregates-- These aggregates are created from crushed ceramics and other lightweight materials. They enhance the thermal performance and reduce the weight of CMUs, providing structural efficiency and sustainability.

3. Geopolymer Concrete-- Made from industrial by-products like fly ash and slag, geopolymer concrete utilizes alkali activation to form a binder, which replaces traditional Portland cement. This process significantly reduces greenhouse gas emissions, offering a more sustainable construction material with a lower carbon footprint.



4. High-Performance Mortars-- These mortars are enhanced with polymers, superplasticizers, and other advanced admixtures to improve bond strength and flexibility. These admixtures allow the mortar to better resist moisture penetration, which is crucial for maintaining structural integrity and durability over time.

5. Integral Water Repellents-- Incorporating water-repellent agents directly into the mortar and CMUs during production ensures uniform distribution. This method enhances resistance to water penetration, minimizing the impact of freeze-thaw cycles and prolonging the lifespan of masonry structures.

6. Lightweight Dry-Cast Concrete Masonry Units-- By integrating lightweight aggregates such as structural grade ceramics, these units can be produced using a dry-cast method. This involves compacting a low-moisture concrete mix into molds, resulting in interconnected void spaces that reduce the overall weight and cement content. These units provide excellent thermal insulation and contribute to CO2 sequestration because of the chemical properties of the materials used.

7. Expanded shale—Produced by expanding a type of clay or shale through a thermal process in rotary kilns. This process involves heating the material to temperatures of around 2,000°F (1,093°C), causing the gases inside to form tiny, non-connecting air voids. This results in lightweight, porous aggregate particles that are hard and durable.  Expanded shale is introduced as an aggregate for Concrete Masonry Units (CMU) blocks primarily to reduce the weight of the blocks without sacrificing strength. The lightweight nature of expanded shale aggregates offers several benefits:
  • Improved Workability: Lighter blocks are easier to handle, which can speed up the construction process and reduce labor costs.
  • Enhanced Insulation: The porous structure of expanded shale aggregates contributes to better thermal insulation properties.
  • Reduced Dead Load: Lighter CMU blocks decrease the overall load on the foundation, which can be particularly beneficial in seismic zones.
  • Sustainability: Using lighter materials can contribute to more energy-efficient buildings.


Innovations Enhancing Masonry
The masonry industry is experiencing innovative advancements that enhance sustainability and performance:

1. CarbonCure Technology:  This method involves injecting captured CO2 into the concrete mix during the production process. The CO2 chemically reacts with calcium ions from cement to form stable calcium carbonate, sequestering carbon while simultaneously improving the strength and durability of the concrete.

2. Photocatalytic Concrete: This type of concrete contains photocatalysts, such as titanium dioxide, which are activated by sunlight. The photocatalysts break down and neutralize airborne pollutants like nitrogen oxides, thus enhancing air quality around masonry structures.

3. Phase Change Materials (PCMs):   PCMs, such as low-temperature liquid paraffin, are integrated into building materials. These substances absorb and store heat when temperatures rise and release heat when temperatures drop. This thermal storage capability helps to regulate indoor temperatures, thereby improving energy efficiency.

4. Self-Healing Concrete:  This technology incorporates bacteria or other healing agents into the concrete mix. When tiny cracks form and moisture infiltrates, the bacteria are activated and produce limestone or other sealing materials, which repair the cracks and extend the lifespan of the masonry structure.



5. Sustainable and Bio-based CMU Materials: These emerging materials include Hempcrete, made from the hemp plant combined with lime-based binders, and bio-based options like microalgae or mycelium (mushroom) bricks. These materials offer sustainable solutions as they are renewable, have lower carbon footprints, and are suitable for both permanent and temporary structures.


Advanced Innovation Technologies in Masonry
Masonry contractors are increasingly leveraging cutting-edge technologies to enhance the performance and efficiency of masonry work:

1. Smart Sensors:  mart sensors are embedded within masonry walls to monitor various parameters such as temperature, humidity, and structural strain. These devices provide real-time data, enabling proactive maintenance by detecting potential issues early, thus ensuring the longevity and optimal performance of the walls.

2. Hygrothermal Analysis: This technology involves analyzing the moisture flow and thermal performance within masonry structures. By using specialized software and sensors, hygrothermal analysis provides insights into how moisture and heat move through the materials over time, helping maintain structural integrity and prevent issues such as mold and deterioration.

3. Thin Veneer and Rainscreen Systems: Thin veneer systems use thinner slices of masonry materials attached to the building’s exterior, significantly reducing material use and weight. Rainscreen systems include an air gap between the veneer and the underlying structure, allowing for better water drainage and air circulation. This enables quicker installations, enhances efficiency and sustainability, and improves the overall durability of the facade.

4. 3D Printing Technology: Utilizing 3D printing technology in masonry involves extruding layers of material to create complex masonry components. This approach allows to produce custom designs and high-tech architectural solutions with precision, reducing waste and improving construction efficiency. NASA and others are investigating the use of 3D masonry extrusion printers to be shipped to the moon to manufacture facilities from onsite materials.  



The Aesthetic and Cultural Value of Masonry
Beyond its practical benefits, masonry offers aesthetic versatility that enables creative architectural solutions. Its ability to blend seamlessly with the natural environment bolsters the cultural heritage of communities. By incorporating traditional masonry techniques, we not only preserve architectural legacies but also contribute to sustainable building practices.

The inherent dignity of masonry architecture imparts a sense of permanence and commitment, shaping the identity of the communities it serves. Masonry's exceptional resilience, sustainability, and economic efficiency make it an ideal choice for constructing durable, environmentally responsible structures. As professionals in the field, it is imperative to advocate for the numerous advantages of masonry, dispelling misconceptions while promoting its sustainability to influence modern construction decisions. In doing so, we uphold principles of durability and community responsibility, contributing to a more sustainable future in architecture.


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