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Better Building: Compressed Earth Blocks Report

CEBs are an emerging earthen construction technology that contribute to stronger and more resilient earth infrastructure. As interest in sustainable construction technology has increased, more research has been conducted on CEBs as an alternative to traditional masonry. Comparing CEB to traditional masonry, CEB structures can be more energy efficient throughout their life cycle. When approached accordingly, they can are energy efficient to produce and transport, while conserving resources and reducing waste production. CEBs are better insulated due to their high thermal mass and thermal resistance. Subsequently, their high thermal inertia gives CEBs the advantage of humidity regulation, and evaporation of water in the earthen walls contributes to natural cooling. CEBs represent a cost effective, energy efficient, and sustainable solution that directly contribute to the ninth and eleventh UN Sustainable Development Goals, which address industry, innovation, and infrastructure, as well as sustainable cities and communities. CEBs indirectly contribute to many other SDGs through their impact on health, household incomes (through cost savings) and quality of life.

CEBs are an emerging earthen construction technology that contribute to stronger and more resilient earth infrastructure. As interest in sustainable construction technology has increased, more research has been conducted on CEBs as an alternative to traditional masonry. Comparing CEB to traditional masonry, CEB structures can be more energy efficient throughout their life cycle. When approached accordingly, they can are energy efficient to produce and transport, while conserving resources and reducing waste production. CEBs are better insulated due to their high thermal mass and thermal resistance. Subsequently, their high thermal inertia gives CEBs the advantage of humidity regulation, and evaporation of water in the earthen walls contributes to natural cooling. CEBs represent a cost effective, energy efficient, and sustainable solution that directly contribute to the ninth and eleventh UN Sustainable Development Goals, which address industry, innovation, and infrastructure, as well as sustainable cities and communities. CEBs indirectly contribute to many other SDGs through their impact on health, household incomes (through cost savings) and quality of life.

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1<br />

The image on the cover comes from a compressed earth block project done by Dwell <strong>Earth</strong>.<br />

Dwell <strong>Earth</strong>’s founder Adam DeJong has a long history of collaboration with Dr. Brett Story, and<br />

is a Hunt Institute Associate. For more information, visit their website: https://dwellearth.com/<br />

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2<br />

Undergraduate Research Analyst:<br />

Madison Rodriguez<br />

Undergraduate Project Manager:<br />

JuliaGrace Walker<br />

Undergraduate Lab Technicians:<br />

Adriana Mena<br />

Ziyu Sun<br />

Graduate Advisors:<br />

Jase Sitton<br />

Robert Hillyard<br />

Global Development Lab Portfolio Manager:<br />

Corrie A. Harris, MA, MBA<br />

Hunt Institute Affiliate:<br />

Dr. Brett Story, Hunt Institute Fellow<br />

Social Entrepreneur:<br />

Adam DeJong<br />

Southern Methodist University<br />

Lyle School of Engineering<br />

Hunter & Stephanie Hunt Institute for Engineering & Humanity<br />

Global Development Lab<br />

Spring 2021<br />

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3<br />

Table of Contents<br />

ABSTRACT ...................................................................................................................................................................................... 5<br />

BACKGROUND ............................................................................................................................................................................... 6<br />

INTRODUCTION ............................................................................................................................................................................ 7<br />

COMPRESSED MASONRY UNIT ALTERNATIVE ................................................................................................................. 8<br />

CEB ADVANTAGES ....................................................................................................................................................................... 8<br />

THERMAL PERFORMANCE ................................................................................................................................... 11<br />

HYGROTHERMAL PROPERTIES ............................................................................................................................ 11<br />

COST-EFFECTIVENESS .......................................................................................................................................... 13<br />

CASE STUDY 1: SCOTLAND .................................................................................................................................................... 15<br />

CASE STUDY 2: MEXICO .......................................................................................................................................................... 16<br />

CONCLUSION ............................................................................................................................................................................... 17<br />

TABLE OF FIGURES ................................................................................................................................................................... 19<br />

APPENDIX: TAOS BUILDING CODE REQUIREMENTS ................................................................................................... 20<br />

REFERENCES ............................................................................................................................................................................... 22<br />

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“…the end goal is to use the data obtained during this project to make recommendations for fullscale,<br />

more permanent structures than can be used by faculty and students at the SMU Taos<br />

campus. The information learned during this project will be used to start the design of a ‘living’<br />

laboratory, which would be a laboratory building constructed with CEB and instrumented with a<br />

variety of sensors. In this way, the structure is both the laboratory space as well as the test<br />

specimen.”<br />

Brett Story, Ph.D., Hunt Institute Fellow<br />

Assistant Professor<br />

Southern Methodist University<br />

Lyle School of Engineering<br />

Department of Civil and Environmental Engineering<br />

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Abstract<br />

<strong>Compressed</strong> <strong>Earth</strong> <strong>Blocks</strong> (CEBs) are an emerging earthen construction technology that<br />

contribute to stronger and more resilient earth infrastructure. As interest in sustainable<br />

construction technology has increased, more research has been conducted on CEBs as<br />

an alternative to traditional masonry. CEBs are a cost effective, energy efficient, and<br />

environmentally friendly solution that contribute to the ninth and eleventh UN Sustainable<br />

Development Goals, which address industry, innovation, and infrastructure as well as<br />

sustainable cities and communities.<br />

Comparing CEB structures to traditional masonry, CEB structures are more energy<br />

efficient for both the construction and operation phases, as they take little energy to<br />

produce and transport, while also conserving resources and reducing waste production.<br />

They also are better insulated due to their high thermal mass and thermal resistance.<br />

Their high thermal inertia gives CEBs the advantage of humidity regulation, and<br />

evaporation of water in the earthen walls contributes to natural cooling. Case studies in<br />

Scotland and Mexico demonstrate the successful implementation of CEB structures and<br />

recommend adjustments for future projects such as increasing ventilation, ensuring<br />

quality control, and using fresh lime.<br />

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Background<br />

This report is a continuation of research that began in partnership with the Hunt Institute<br />

and Dr. Brett Story in 2015. This project addresses the ninth and eleventh UN Sustainable<br />

Development Goals of industry, innovation, and infrastructure, as well as sustainable<br />

cities and communities.<br />

Phase I focused on the strength testing of CEBs under a variety of conditions including<br />

varying moisture levels, cement content, and soil type. Phase II focused on determining<br />

local soil characteristics for different types of soil found globally as a first step in<br />

standardization. Designing with CEB requires an understanding of the local soil conditions<br />

and how composition, moisture, and other variables interact and affect construction.<br />

This process is taught by Dwell <strong>Earth</strong>, an organization dedicated to spreading this<br />

knowledge through hands-on training workshops to share their efficient and intuitive<br />

building system. Founder, Adam De Jong, is an Affiliate in the Institute and has<br />

consistently provided his expertise to Dr. Story over the years as he expands his research<br />

now into Phase III.<br />

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Introduction<br />

Phase III intends to compare data pulled from three small-scale prototype structures built<br />

from insulated plywood, concrete masonry unit (CMU), and CEB. Duplicate prototypes<br />

will produce data to analyze from two locations, one at the SMU @ Taos campus and the<br />

second at SMU's main campus in Dallas, TX. Phase III will use the test structures at both<br />

the Taos and Dallas campuses to investigate relationships between soil type and mix<br />

design, block strength, and thermal properties. This investigation will also include models<br />

developed by Dr. Story’s lab team, which includes Ph.D. students Jase Sitton and Robert<br />

Hillyard as well as undergraduate researchers Adriana Mena and Ziyu Sun.<br />

The Hunt Institute team includes an undergraduate project manager and the<br />

undergraduate research analyst, Madison Rodriguez. This team’s report analyzes<br />

building requirements when using CEB in New Mexico and informs the vision of a living<br />

laboratory in SMU @ Taos. This living laboratory will be a more permanent structure for<br />

continued observation and data gathering, exploring the scalability of compressed earth<br />

blocks through the construction and testing of smaller blocks. This project will assess the<br />

feasibility for long term testing at both campuses, allowing for a unique comparison<br />

between an urban and rural area within extreme climates with varying soil types.<br />

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<strong>Compressed</strong> Masonry Unit Alternative<br />

<strong>Earth</strong>en building is one of the oldest and most widespread building techniques. It is<br />

estimated that at least 30% of the world’s population live in houses constructed of raw<br />

earth. [1] CEBs represent a recent development in earthen building that allows for stronger,<br />

more resilient earthen structures to be constructed. CEBs are masonry units formed using<br />

a mixture of local soil, water, aggregate (typical sand), and a stabilizer, which is typically<br />

portland cement or hydrated lime. This mixture is machine-compressed into a mold to<br />

create blocks which are allowed to cure for approximately 28 days. No firing is necessary<br />

in the formation of CEBs, which results in reduced greenhouse gas emissions during the<br />

production process when compared to traditional fired clay bricks.<br />

Growing interest in CEBs as an alternative to traditional construction techniques is due to<br />

the popular demand for sustainable technology. Research applied toward production of<br />

an environmentally sustainable earth building block has found that some variations are<br />

capable of meeting current concrete block performance specifications while reducing<br />

embodied energy by as much as 50%. [2] CEB construction has undergone significant<br />

advancements over the past decades such as improved block composition and geometry.<br />

Unfortunately, a lack of standardization has prevented the widespread implementation of<br />

CEB construction.<br />

As it stands, concrete is the most manufactured product in the world, with annual<br />

consumption approaching 20,000 million metric tons and each metric ton resulting in 900<br />

kilograms of carbon dioxide released into the air. [2] With the successful standardization<br />

and widespread adoption of CEB construction, pollution from building materials and waste<br />

from excavation and construction could all be greatly reduced.<br />

CEB Advantages<br />

Due to using local soil as the primary mix design component, CEBs are a cost-effective,<br />

energy efficient, and environmentally friendly building solution. With soil as an abundant<br />

natural resource in most regions, extraction and material costs are greatly reduced. [3] The<br />

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soil used to produce the CEB is often found on-site, thus reducing associated<br />

transportation costs. [3] Other common CEB mix design components, such as sand, water,<br />

and stabilizer, are frequently available locally even in developing areas. [4]<br />

Construction of CEBs requires minimal skillset and some specialized equipment (see<br />

Figure 1) to compress the earth blocks. The earth block compression machines can be<br />

operated by hand by several workers. This allows for community members to partake in<br />

the construction of CEB houses and community buildings, which reduces labor costs,<br />

creates jobs, and benefits the local economy. [5] A comparative cost analysis performed<br />

by Guillaud et al. (1995) showed that a CEB house costs 32% less than a similar house<br />

constructed with traditional sand-cement blocks. [6]<br />

Figure 1: Photo of Dwell<strong>Earth</strong>’s <strong>Earth</strong> Blox BP714<br />

CEB structures are more energy efficient than traditional masonry structures for both the<br />

construction and operation phases. From a production standpoint, CEBs require<br />

significantly less energy to produce than other masonry units. Compared to CMU, CEB<br />

requires less cement; while a typical CMU will contain around 10-16% cement by weight,<br />

a CEB will usually only contain around 6%. [3] Compared to fired clay bricks, CEB does not<br />

require firing during production which reduces carbon emissions and energy input.<br />

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The soil in CEB acts as a natural regulator between indoor and outdoor temperatures. [7]<br />

This is in sharp contrast to the heat loss and overheating characteristics (dehydration and<br />

non-uniform particle distribution) of other industrialized materials like concrete in CMU. [7]<br />

In essence, earthen structures are often warmer in the winter and cooler in the summer<br />

than other structures, meaning less energy will be required to heat and cool the<br />

structure. [8] The thermal mass storage and heat transmission capabilities of soil in CEBs<br />

are capable of controlling temperature fluctuations within a space to provide a more<br />

comfortable indoor environment. [3]<br />

A key quality of CEB that aids in temperature regulation is the ability to absorb and release<br />

water vapor as ambient humidity levels fluctuate. [9] <strong>Earth</strong>en walls have a thermal and<br />

moisture buffering capacity that stabilizes the relative humidity and temperature inside a<br />

structure, thus increasing indoor comfort. [10] A preliminary study conducted by Dr. Brett<br />

Story found that humidity and temperature levels fluctuate the least in CEB structures<br />

when compared to other building methods. It was also concluded that from a heating and<br />

cooling standpoint, less energy is required to construct and inhabit a CEB structure than<br />

a structure of identical size made from alternative masonry units.<br />

CEB construction is sustainable and energy efficient, as it requires little energy to produce<br />

and transport, conserves natural resources, reduces landfill waste, and reduces the<br />

energy consumption of the building. [11] All of these factors combine to minimize the CO2<br />

released into the atmosphere.<br />

Since CEBs are made from natural material, they do not give off any harmful chemicals<br />

found in typical building materials such as drywall. [12] The use of CEB structures prevents<br />

exposure to formaldehyde, asbestos, VOC´s, and dozens of other chemicals leaching<br />

dangerous toxins into the air, as the earth itself acts as a natural air filter. [13] <strong>Earth</strong>en walls<br />

also absorb pollutants from both indoor and outdoor environments. [12] These benefits<br />

produce healthier environments for occupants.<br />

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Thermal Performance<br />

CEBs have high thermal mass and thermal resistance (and, thus, low thermal<br />

conductivity), which are desirable characteristics from an energy efficiency standpoint.<br />

The thermal regulation characteristics of CEBs can be measured in terms of their thermal<br />

transmittance (U-value) and thermal resistance (R-value). [14] The U-value is typically used<br />

to measure the rate of heat transfer through a structure. [15] The R-value, which is the<br />

reciprocal of the U-value, measures the insulating material’s resistance to conductive heat<br />

flow. [15] Typically, a high R-value directly correlates to a well-insulated structure. Table 1<br />

shows this inverse relationship for some common materials.<br />

Soil Mix R-value (K・m 2 /W) U-value (W/m 2 ・K)<br />

Concrete <strong>Blocks</strong> 0.090 1.13<br />

Glasswool 2.500 0.04<br />

Clay Bricks 0.130 0.77<br />

Table 1: Typical R-values for Masonry Materials<br />

A well-insulated structure is beneficial in both cold and warm climates. [14] With the low<br />

thermal conductivity of CEB, heat transfer through a CEB structure is a slow process,<br />

which helps keep the interior cool when the outside temperature is high and, conversely,<br />

keep the interior warm when the outside temperature is low. [4,5,16,17] This reduces the<br />

energy needed to control the indoor temperature as temperature fluctuations are less<br />

severe.<br />

Hygrothermal Properties<br />

CEBs are able to regulate the relative humidity of indoor air and can improve the<br />

hygrothermal behavior of structures due to their high thermal inertia. [17] The main<br />

components in CEBs allow for constant improvement of the comfort levels and<br />

hygrothermal behavior of CEB structures. CEB are able to transfer moisture to and from<br />

the air faster than other building types. [17]<br />

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Moisture transfer has two direct consequences for the indoor environment. Firstly, the<br />

earthen walls can regulate the relative humidity inside the building and the damping of<br />

humidity variation in buildings helps to increase indoor comfort. Secondly, evaporation of<br />

the water contained within the earthen walls can have a cooling effect in hot weather. [17]<br />

Figure 2: Illustration on the Effect of Low Carbon CEB Structures on Humidity Levels<br />

Figure 2 shows the ability of the earthen materials in CEB to regulate internal humidity. [18]<br />

Bedroom 1 and Bedroom 2 followed similar patterns; over time, they both experienced<br />

similar fluctuations of humidity percentage. The data shows that throughout the day, the<br />

humidity is lower in the living room than the other rooms. As seen in the graph, the<br />

moisture content of the bathroom is relatively close to the moisture content of the two<br />

bedrooms throughout the day. The external air has a higher humidity level than the inside<br />

rooms; there is about a 20% difference between the inside and outside at all points<br />

throughout the day.<br />

The mean indoor humidity value was 45%, while the mean external air humidity value<br />

was around 65%. [18] According to the Mayo Clinic, ideal indoor humidity levels are<br />

between 30%-50%, which this CEB structure was able to maintain. While there were<br />

some short-term spikes in indoor humidity levels, the data shows how the CEB were able<br />

to return to an ideal moisture value. There was a particularly strong response recorded in<br />

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the bathroom where the CEB were able to absorb peaks of air moisture after showers,<br />

clearing the air without surface condensation; the extract fan by comparison had no<br />

statistically significant effect. [18] A comparison of this effect can be found in Figure 3.<br />

Figure 3: Illustration on the Effect of Low Carbon CEB Structures on Moisture Content Levels<br />

The results from Figure 3 indicate that peaks in air moisture resulting from showers or<br />

cooking were absorbed by CEB wall materials and stored to be released later when air<br />

moisture levels dropped. [18] The ability of CEB to absorb and retain moisture prevents<br />

potentially damaging condensation buildup and avoids the need for vapor control<br />

membranes. [18] This is significant, as it directly affects the occupants’ health, particularly<br />

those suffering from asthma.<br />

Cost-effectiveness<br />

Over the past four decades, homes in the U.S. have become considerably more energy<br />

efficient over the past four decades. Unfortunately, the increasing average home size has<br />

wiped out nearly all the efficiency gains. [19] According to a 2015 survey conducted by the<br />

U.S. Energy Information Administration, 32% of residential electricity consumption was<br />

used for the heating and cooling of the building. As seen in Figure 4, additional electricity<br />

consumption is used for heating and cooling.<br />

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Figure 4: Illustration of 2015 Residential Electricity Consumption by End Use<br />

Similarly, Figure 5 shows approximately 32% of commercial electrical consumption is<br />

allocated for heating, cooling and ventilation of commercial buildings.<br />

Figure 5: Illustration of 2006 Energy Use in U.S. Commercial <strong>Building</strong>s by End-Use<br />

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A CEB occupancy case study conducted in Scotland found that its occupants were very<br />

satisfied with the energy consumption of the house. After one year of residence, annual<br />

space and water costs average £300 ($388) which is significantly lower than the £700 to<br />

£900 ($905 to $1,163) the average Scottish home uses for space heating alone. [18] The<br />

occupants also felt sufficiently comfortable to have the heating system turned off between<br />

March 3rd and October 21 where temperatures range from 36F to 66F. These occupancy<br />

comfort levels demonstrate the beneficial effects of passive energy gains, thermal mass,<br />

high standards of insulation, and air tightness. [18]<br />

Additionally, the annual energy used for space and water heating was 66.5 gigajoules<br />

(GJ) which is significantly lower than the 900 GJ annual average for a CMU home located<br />

in the same community. [18] Overall, the occupants of this CEB house (Figures 6 and 7)<br />

were satisfied with the construction costs, energy efficiency and aesthetic.<br />

Figure 7: Scottish CEB Home currently in use since<br />

2005<br />

Figure 6: Scottish CEB Home currently in use since<br />

2005<br />

Case Study 1: Scotland<br />

In 2005, CEB experts in Dalguise, Dunkeld, Scotland designed a CEB structure<br />

(Figures 8 and 9) that is currently in use. The material in the structure consists of 45%<br />

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alluvial clay, 5% sand, and 50% wood shavings. The average compressive strength and<br />

shear strength were 2.5 N/mm2 and 0.16 N/mm2, respectively.<br />

According to the occupants and recorded data, the Scottish CEB structural performance<br />

was acceptable. The internal air relative humidity was controlled between 40%-60%<br />

including the bathroom. The annual space and heating costs were only $385.<br />

Figure 8: Scottish CEB Homes Currently in Use Since 2005<br />

Some drawbacks include minor cracking after one year of habitation and higher than<br />

expected energy consumption values. In the future, interested parties seeking to design<br />

and construct CEB structures should prioritize quality control and site management<br />

during CEB and housing construction. They should also increase ventilation at the<br />

upper level of the house.<br />

Case Study 2: Mexico<br />

In 2004, CEB experts in Loreto Bay, Baja California, Mexico designed and constructed<br />

a CEB village structure (Figure 9) that is currently in use. The material in the structure<br />

consists of 65% locally-mined clay, 30% sand, and 5% lime. Each CEB block averaged<br />

the following dimensions: 4 in x 14 in x 10 in.<br />

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According to the occupants and recorded data, the Mexican CEB structural<br />

performance was acceptable. The structure required less energy than expected to<br />

maintain comfortable room temperatures. By becoming LEED certified, standards for<br />

energy and water consumption further decreased the expected consumption rates.<br />

Construction of the CEB structures created 4,500 permanent jobs and several thousand<br />

short-term jobs to locals.<br />

In the future, interested parties seeking to design and construct CEB structures should<br />

use fresh lime, as gray lime has absorbed humidity and will not be as effective. They<br />

should also consider the cultural and environmental impact on the surrounding towns. It<br />

is also recommended to provide security during the construction phases.<br />

Figure 9: Mexican CEB Village Currently In Use Since 2004<br />

Conclusion<br />

Recently, there has been a growing interest in CEBs as an alternative to traditional<br />

construction techniques. This report analyzes the characteristics of CEBs that contribute<br />

to their sustainability, reliability, and energy efficiency. These include their high thermal<br />

mass, thermal resistance, and thermal inertia. These properties are shown to lead to<br />

better insulation, humidity regulation, and natural cooling than traditional masonry<br />

construction.<br />

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CEBs are certainly a promising technology in the field of sustainable construction. In order<br />

to facilitate their implementation in common engineering design, more research and<br />

analysis is required. This will involve continued support for further investigation, including<br />

Dr. Story’s lab research on CEBs and later the construction of a small CEB shed at the<br />

SMU Taos campus.<br />

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Table of Figures<br />

Figure 1: Photo of Dwell<strong>Earth</strong>’s <strong>Earth</strong> Blox BP714 ........................................................................ 9<br />

Figure 2: Illustration on the Effect of Low Carbon CEB Structures on Humidity Levels .............. 12<br />

Figure 3: Illustration on the Effect of Low Carbon CEB Structures on Moisture Content Levels 13<br />

Figure 4: Illustration of 2015 Residential Electricity Consumption by End Use ........................... 14<br />

Figure 5: Illustration of 2006 Energy Use in U.S. Commercial <strong>Building</strong>s by End-Use ................ 14<br />

Figure 6: Scottish CEB Home currently in use since 2005 .......................................................... 15<br />

Figure 7: Scottish CEB Home currently in use since 2005 .......................................................... 15<br />

Figure 8: Scottish CEB Homes Currently in Use Since 2005 ...................................................... 16<br />

Table 1: Typical R-values for Masonry Materials ......................................................................... 11<br />

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Appendix: Taos <strong>Building</strong> Code Requirements<br />

A Brief Review of <strong>Compressed</strong> Stabilized <strong>Earth</strong> Brick by Riza, Rahman, Zaidi<br />

The following are recommendations of building codes for CEB structural design,<br />

development, and construction. These are based on Riza, Rahman, and Zaidi’s 2010<br />

published research article.<br />

● <strong>Compressed</strong> Stabilized <strong>Earth</strong> Brick (CSEB) requires compaction and the content<br />

of stabilizer added for gaining its strength<br />

● During curing, it is important to prevent rapid drying. It is recommended to store<br />

moist bricks stacked under a polythene sheet for 28 days.<br />

● Soil with plasticity index below 15 is suitable for cement stabilization.<br />

● Cement binder is added between 4 and 10 % of the soil dry weight<br />

● If the content of cement is greater than 10%, then it becomes uneconomical.<br />

● For brick using less than 5% of cement, it will crumble easily.<br />

● For soil that has a plasticity index below 15, it is suggested to use lime as a<br />

stabilizer.<br />

● The strength of the CSEB can be increased by adding natural fibers where it can<br />

improve the ductility in tension.<br />

<strong>Building</strong> with <strong>Compressed</strong> <strong>Earth</strong> Block within the <strong>Building</strong> Code by Holliday, Ramseyer,<br />

Reyes, Butko<br />

The following are recommendations of building codes for CEB structural design,<br />

development, and construction. These are based on Holliday, Ramseyer, Reyes, and<br />

Butko’s 2016 published research article.<br />

● To create a sufficiently strong CEB, the soil must be placed under a compressive<br />

pressure, approximately 1,500 - 2,500 psi, which can be done with a manual or<br />

mechanized press.<br />

● The soil being used for manufacturing CEBs must first be screened to remove<br />

organic and inorganic debris.<br />

● Once the soil has been screened, it is mixed with stabilizer and water to ensure<br />

proper moisture content.<br />

● It is recommended to let CEBs cure for 28 days before excessive handling,<br />

transport and installation.<br />

● Once CSEB are sufficiently cured, they can be stacked as masonry units in walls.<br />

● The standard practice for CEB walls is to use a soil-based slurry in lieu of a<br />

cementitious mortar. The mix for the slurry is similar to that used in the blocks,<br />

made by mixing screened soil through a finer sieve, portland cement, and water.<br />

● Code officials’ requirements: (1) the wall sections must have demonstrated a<br />

minimum thermal resistance (R value), and (2) the structural plans must have<br />

been signed by a registered engineer.<br />

● Wall sections must be tested in the lab to determine their strength to withstand<br />

vertical compression and horizontal shear loads both in and out of plane.<br />

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● Once wall properties are determined, a structural engineer can determine<br />

whether the walls were sufficient to resist the loads designated by the building<br />

code and authorize the structural drawings.<br />

● CEBs should have an R value greater than that of adobe. The IBC section on<br />

adobe requires a minimum 21.2 kg/cm2 (300 psi) compressive strength and a<br />

minimum 3.5 kg/cm2 (50 psi) modulus of rupture.<br />

● New Mexico <strong>Building</strong> Code suggests a minimum compressive strength of 2.07<br />

MPa<br />

● All bearing walls must be topped with a continuous (concrete or wood) bond<br />

beam<br />

● There are several ways to reinforce CEB walls such as:<br />

○ Drilling holes for rebar<br />

○ Mesh reinforcing on the outside of CEB walls<br />

The Selection of Soils for Unstabilized <strong>Earth</strong> <strong>Building</strong>: A Normative Review by Jimenez<br />

Delgado, Canas Guerrero<br />

The following are recommendations of building codes for CEB structural design,<br />

development, and construction. These are based on Delgado and Guerrero’s 2007<br />

published research article.<br />

● Unstabilized soil is defined as soil not containing binding additives such as<br />

cement.<br />

● The maximum particle grain size for CEB is 20 mm.<br />

● Check the presence of organic material because it could cause instability.<br />

● The clay content (size


22<br />

References<br />

[1]<br />

Keefe, L. (2005). <strong>Earth</strong> <strong>Building</strong>: Methods and Materials, Repair and Conservation.<br />

Routledge.<br />

[2]<br />

Dahmen, J. & Munoz, J. (2014). <strong>Earth</strong> Masonry Unit: Sustainable CMU Alternative.<br />

Construction Materials and Environment, 6(2), 903-909.<br />

[3]<br />

Sitton, J. (2017). Rapid Soil Classification and Strength Characterization to Advance<br />

Standardization of <strong>Compressed</strong> <strong>Earth</strong> <strong>Blocks</strong>. Southern Methodist University.<br />

[4]<br />

Adam, E.A. & Agib, A.R.A. (2001). <strong>Compressed</strong> Stabilised <strong>Earth</strong> Block Manufacture in<br />

Sudan. United Nations Educational, Scientific and Cultural Organization.<br />

[5]<br />

Bowen, T. (2017). A Best Practices Manual for Using <strong>Compressed</strong> <strong>Earth</strong> <strong>Blocks</strong> in<br />

Sustainable Home Construction in Indian Country. University of Colorado, Boulder.<br />

[6]<br />

Guillaud, H., Joffroy, T., & Odul, P. (1995). <strong>Compressed</strong> <strong>Earth</strong> <strong>Blocks</strong>: Manual of<br />

Design and Construction. German Appropriate Technical Exchange.<br />

[7]<br />

Mbereyaho, L., Tubarimo, J., & Halera, J. (2018). Study on energy efficiency of earth<br />

blocks. INES Scientific Journal, 13, 98-114.<br />

[8]<br />

Bachar, T., Abdelhamid, G., Guettala, S., & Kriker, A. (2014). Mechanical properties<br />

and hygroscopicity behavior of compressed earth block filled by date palm fibers.<br />

Construction and <strong>Building</strong> Materials. 59. 161–168.<br />

10.1016/j.conbuildmat.2014.02.058.<br />

[9]<br />

Allen, G. T., & Liel, A. (2012). Strength properties of Stabilized <strong>Compressed</strong> earth<br />

blocks with Varying Soil compositions. University of Colorado at Boulder.<br />

[10]<br />

Cherif, A., Saidi, M., Sediki, E. & Zeghmati, B. (2018). Stabilization effects on the<br />

thermal conductivity and sorption behavior of earth bricks. Construction and<br />

<strong>Building</strong> Materials, 167, 566-577.<br />

https://doi.org/10.1016/j.conbuildmat.2018.02.063<br />

[11]<br />

Rael, R. (2009). <strong>Earth</strong> Architecture. Princeton Architectural Press.<br />

[12]<br />

One Community. (2019). <strong>Compressed</strong> <strong>Earth</strong> Block Village - One Community Pod 4.<br />

Retrieved April 27, 2021, from https://www.onecommunityglobal.org/compressedearth-block-village/#advantages<br />

BETTER BUILDING: COMPRESSED EARTH BLOCKS REPORT<br />

RODRIGUEZ, MADISON


23<br />

[13]<br />

Roberts, T. (2017, Aug 31). Health Benefits of Natural <strong>Earth</strong>en Construction. The<br />

Permaculture Research Institute.<br />

https://www.permaculturenews.org/2017/08/31/health-benefits-natural-earthenconstruction/<br />

[14]<br />

Afework, B., Donev, J., Hanania, J. & Stenhouse, K. (2018, May 18). U-value.<br />

University of Calgary. https://energyeducation.ca/encyclopedia/U-value<br />

[15]<br />

Lymath, A. (2015, Feb 1). What is a U-value? Heat loss, thermal mass and online<br />

calculators explained. NBS. https://www.thenbs.com/knowledge/what-is-a-uvalue-heat-loss-thermal-mass-and-online-calculatorsexplained#:~:text=Thermal%20transmittance%2C%20also%20known%20as,the<br />

%20U%2Dvalue%20will%20be.<br />

[16]<br />

Datta, U.S. & Mustafa, B. (2016). A Comparative Study of the Thermal Performance<br />

of Mud and Brick Houses in Bangladesh. <strong>Building</strong> the Future ‘sustainable and<br />

resilient environments’, 250-262.<br />

[17]<br />

Aubert, J.E., Cagnon, H., Coutand, M. & Magniont, C. (2014). Hygrothermal<br />

properties of earth bricks. Energy and <strong>Building</strong>s, 80, 208-217.<br />

https://doi.org/10.1016/j.enbuild.2014.05.024<br />

[18]<br />

Morton, T., Smith, N., Stevenson, F. & Taylor, B. (2005). Low Cost <strong>Earth</strong> Brick<br />

Construction. Arc, Chartered Architects.<br />

[19]<br />

DeSilver, D. (2015). Bigger homes wiping out energy efficiency gains. Retrieved<br />

April 27, 2021, from https://www.pewresearch.org/fact-tank/2015/11/09/asamerican-homes-get-bigger-energy-efficiency-gains-are-wiped-out/<br />

BETTER BUILDING: COMPRESSED EARTH BLOCKS REPORT<br />

RODRIGUEZ, MADISON

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