With fly ash, a byproduct of coal burning power plants, this waste material is now being banned from most landfills worldwide. The huge issue of there disposal is creating worldwide problems. Hundreds of millions of tons are generated in the US alone each year. Since there is not enough room for mass land filling of garbage, something has to be done quickly or we will be buried in fly ash. This growing problem of disposal of these safe and inert materials needs answers now! As you can see in the attached picture, this is what a fly ash mountain looks like. Mountain views like this are not what we want to see in America, or anywhere else for that matter. Environmental Construction Technologies has a safe ecological solution for mass recycling of fly ash byproducts. Fly ash primarily originates from coal burning power plants and other several other coal burning industries. We can recycle up to one hundred tons of material for each average size home of 2,000 square feet.

ADVERTISEMENTS OFTEN PROMISE R-30 from a lightweight masonry block wall system. Log home product literature claims that log walls insulate as well as fiberglass because of the thermal mass. Salesmen at a trade show argue that a new fiber-cement building system achieves R-28 even though the "tested" R-value comes in at only R-16. What's going on here? Do these claims of "effective R-values" that greatly exceed the widely published R-values for high-mass materials hold up? Just what effect does thermal mass have on the energy performance of an exterior wall system? The issue of thermal mass and its effect on the energy performance of buildings is one of the most confusing issues facing designers, builders, and buyers of buildings today. This article tries to sort out these mysteries, providing enough background on the physics of heat transfer to understand the relationship between thermal storage and heat flow, and then explaining when this information is relevant and how it should be used in building design. This article does not address the use of thermal mass inside a building, where it can store heat (or coolth) and even out temperature fluctuations. Understanding Heat Transfer Heat flows by three mechanisms: conduction, convection, and radiation. Conduction is the molecule-to-molecule transfer of kinetic energy (one molecule becomes energized and, in turn, energizes adjacent molecules). A cast-iron skillet handle heats up because of conduction through the metal. Convection is the transfer of heat by physically moving the molecules from one place to another. Hot air rises; heated water thermosiphons; our forced-air heating systems work by moving hot air from one place to another. Radiation is the transfer of heat through space via electromagnetic waves (radiant energy). A campfire can warm you even if there is wind between you and the fire, because radiation is not affected by air. With buildings, we refer to heat flow in a number of different ways. The most common reference is "R-value," or resistance to heat flow. The higher the R-value of a material, the better it is at resisting heat loss (or heat gain). U-factor (or "U-value," as it is often called) is a measure of the flow of heat--thermal transmittance--through a material, given a difference in temperature on either side. In the inch-pound (I-P) system, the U-factor is the number of Btus (British Thermal Units) of energy passing through a square foot of the material in an hour for every degree Fahrenheit difference in temperature across the material (Btu/ft2hr°F). In metric, it's usually given in watts per square meter per degree Celsius (w/m2°C). R-values are measured by testing laboratories, usually in something called a guarded hot box. Heat flow through the layer of material can be calculated by keeping one side of the material at a constant temperature, say 90°F (32°C), and measuring how much supplemental energy is required to keep the other side of the material at a different constant temperature, say 50°F (10°.C)--all this is defined in great detail in ASTM (American Society of Testing and Materials) procedures. The result is a steady-state R-value ("steady-state" because the difference in temperature across the material is kept steady). R-value and U-factor are the inverse of one another: U = 1/R. Materials that are very good at resisting the flow of heat (high R-value, low U-factor) can serve as insulation materials. So far, so good. Materials have another property that can affect their energy performance in certain situations: heat capacity. Heat capacity is a measure of how much heat a material can hold. The property is most significant with heavy, high-thermal-mass materials. As typically used in energy performance computer modeling, heat capacity is determined per unit area of wall. For each layer in a wall system, the heat capacity is found by multiplying the density of that material, by its thickness, by its specific heat (specific heat is the amount of heat a material can hold per unit of mass). Water has a heat capacity of 1 Btu/lb.°F (4.2 kJ/kg°K), while most building materials are around 0.2 to 0.3 Btu/lb.°F (0.8 to 1.3 kJ/kg°K). If there are various layers in the wall, total heat capacity is found by adding up the heat capacities for each layer (drywall, masonry block, and stucco, for example). In the following section, we will examine how the heat capacity of materials can affect the energy performance of buildings. "Mass-Enhanced R-Value" When people refer to the "mass effect" or "effective R-value," they are generally referring to the ability of high-mass materials, when used in certain ways, to achieve better energy performance than would be expected if only the commonly accepted (steady-state) R-value or U-factor of that material were considered. Let's take a look at a typical use of one of these high-mass materials in a wall system. When one side of the wall is warmer than the other side, heat will conduct from the warm side into the material and gradually move through it to the colder side. If both sides are at constant temperatures--say the inside surface at 75°F (42°C) and the outside surface at 32°F (18°C)--conductivity will carry heat out of the building at an easily predicted rate. As described above, this steady-state heat flow is what most test procedures for determining R-value measure. In real-life situations, however, the inside and outside temperatures are not constant. In fact, in many parts of the country, the driving force for conductive heat flow (remember, heat always moves from warmer to colder) can change dramatically or even reverse during the course of a day. On a summer afternoon in Albuquerque, New Mexico, for example, it might be 90°F (32°C) outside, and the outside wall surface--because it has a dark stucco--might be even hotter. It's cooler inside, so heat conducts from the outside surface of the wall inward. As night falls, however, it cools down outside. The air temperature may drop to 50°F (10°C). The driving force for heat flow changes. As the temperature difference across the wall is reversed, the heat flow is also reversed--drawing heat back towards the outside of the building. As a result of this modulating heat flow through a high-heat-capacity material, less heat from outside the building makes its way inside. Under these conditions, the wall has an effective thermal performance that is higher than the steady-state R-value listed in books (such as ASHRAE's Handbook of Fundamentals). This dynamic process is what some people call the "mass effect." Another common scenario is when the outside temperature fluctuates but never crosses the indoor setpoint temperature. In this case, the direction of heat flow never changes, but the thermal lag or time delay in heat flow can still be beneficial by delaying the peak heating or cooling load. For example, if the outdoor temperature in Miami peaks at 95°F (35°C) at 5:00 on a summer afternoon, but it takes eight hours for the heat to travel through the wall, the effect of that peak temperature won't be felt inside the building until the middle of the night. Because most cooling equipment operates at higher efficiency if the outdoor air temperature is lower and because nighttime thermostat settings may be higher (at least in commercial buildings), potentially significant savings can result. Not only can total cooling energy be reduced, but peak loads can also be reduced. This can lead to smaller (and less costly) mechanical systems and lower demand charges for electricity. This time lag effect can save energy and money, but note that it does not affect the total amount of heat flowing through the wall. As noted above, the amount of heat flow through a wall is reduced by the use of thermal mass when the temperatures fluctuate above and below the desired indoor temperature, so under these conditions a material might have a "mass-enhanced" R-value that is greater than its steady-state R-value. To estimate this mass-enhanced R-value for a given high-mass material in a particular climate, researchers at Oak Ridge National Laboratory measure the thermal performance of a high-mass wall under dynamic conditions, in which the temperature on one side of the wall is kept constant and the temperature on the other side is made to fluctuate up or down. With this measured heat flow under dynamic conditions as a basis, they then use computer modeling to arrive at steady-state wall R-values that would be required to achieve comparable overall energy performance under various climate conditions. Those results are what we are calling the "mass-enhanced R-values" for the high-mass material under the modeled conditions. (Others refer to this as the effective R-value, a term that can be misleading.) The multiplier obtained by dividing the mass-enhanced R-value of a material in a given climate by its steady-state R-value is referred to by Oak Ridge researchers as the Dynamic Benefit for Massive Systems (DBMS). When is Mass-Enhanced R-Value Significant? The mass effect is real. High-mass walls really can significantly outperform low-mass walls of comparable steady-state R-value--i.e., they can achieve a higher "mass-enhanced R-value." BUT (and this is an important "but"), this mass-enhanced R-value is only significant when the outdoor temperatures cycle above and below indoor temperatures within a 24-hour period. Thus, high-mass walls are most beneficial in moderate climates that have high diurnal (daily) temperature swings around the desired indoor setpoint. Nearly all areas with significant cooling loads can benefit from thermal mass in exterior walls. The sunny Southwest, particularly high-elevation areas of Arizona, New Mexico and Colorado, benefit the most from the mass effect for heating. In northern climates, when the temperature during a 24-hour period in winter is always well below the indoor temperature, the mass effect offers almost no benefit, and the mass-enhanced R-value is nearly identical to the steady-state R-value. The ASHRAE Handbook of Fundamentals lists "mean daily temperature range" data for hundreds of U.S. climates in the chapter on climate data. These values can be helpful in figuring out how significant mass-enhanced R-value might be for a particular climate, but they do not tell the whole story; also significant is the percentage of days during the heating and cooling seasons when the outdoor temperature cycles above and below the indoor temperature. Do We Need Mass-Enhanced R-Value Ratings? Clearly, high-mass materials used in exterior walls perform better than would be expected based solely on their steady-state R-values. But the actual thermal performance is highly dependent on where the building is located. Manufacturers of these materials rightly want to take credit for this improved performance, but how can that be done in a way that doesn't exaggerate performance for parts of the country where the mass effect benefit just isn't there? "Right now, we don't have a system that forces people to deal with calculations in a constant way," says Bruce Wilcox, P.E., of the Berkeley Solar Group, who has done extensive modeling of mass effects for the Portland Cement Association and others. All sorts of claims are being made about mass-enhanced R-value (usually called "effective R-value") with little standardization. The first step needs to be consensus on how the mass effect should be accounted for in testing and modeling. Jeffrey Christian at Oak Ridge National Laboratory has been developing and refining the method of dynamic thermal analysis and simulation described above. This is the most extensive effort to date to quantify the mass effect. Christian's group, with the help of Bruce Wilcox and others, also developed thermal mass tables for the Model Energy Code in the late 1980s that can be used to account for the thermal mass benefits of high-mass building materials in wall systems. The next step, suggests Christian, might be to formalize the testing and simulation procedures through development of ASTM standards. Establishment of an ASHRAE committee to address the mass effect may also be in the works. To ensure that such standards would be applied in a consistent manner, Wilcox suggests that applicable industries might have to set up some sort of council, perhaps modeled after the National Fenestration Rating Council (NFRC), which enforces consistent reporting of window energy performance. Such a "Thermal Mass Rating Council" might oversee standards relating to how mass effect and mass-enhanced R-value are reported. Wilcox remains leery of the whole concept of mass-enhanced R-value--not that the effect exists, but whether it can be used clearly with building materials. "I don't know if there's any way to make it a property of the material," he told EBN, "It's a property of the system." There are a lot of questions to sort out, such as how many climates need to be modeled: are six enough, as Oak Ridge researchers have used, or do we need 20? Would such a system take credit for time delays in heat transfer, or just actual reductions in the amount of heat that moves through? Who will pay for all the research to make this happen? Are the industries that sell high-mass materials large enough to support a Thermal Mass Rating Council and the additional research needed on these issues? Final Thoughts High-mass building materials can offer significant energy benefits in exterior walls. The benefit may be primarily in the shifting of peak load conditions or in an actual reduction in overall heat gain or loss. These benefits are highly dependent upon where the building is located, how it is designed, and how it is operated. How we should give credit--in terms of energy performance--for high-mass building materials is still very much open for debate. Until standardized procedures for determining the regional significance of the mass effect are widely applied, there will likely be continued confusion and continued exaggeration regarding the energy benefits of thermal mass. Oak Ridge researchers and companies are helping to bring these issues into public awareness, but a great deal of work remains to be done. Evaluating Compressed Earth Block or Brick (CEB) walls and the overall Thermal Performance given all R and U factors. For centuries, dwellers in earth-constructed homes have experienced relative comfort. Earth homes with massive walls were reported to stay cooler in hot weather and to stay warm when temperatures became cooler. However, measurements of wall performance did not entirely support these claims. What is the explanation? When assessing thermal properties and performance, materials have been evaluated traditionally based on measurements of their R– and U–values. The R-value indicates a wall’s ability to insulate effectively. Insulation is nothing more than the resistance of a material to transfer heat. The higher the R-value, the better the insulator. The R-value is calculated by dividing the thickness of the wall by the wall’s thermal conductivity, a value that is calculated by measuring the amount of heat per square foot that flows from the warmer side of a wall to its cooler side. The U-value of a wall is the reciprocal of the R-value and represents the rate at which heat is conducted through a material. Thermal Bridging: There is good evidence that installed R-values of "typical" wall constructions only deliver in the field about 42% to 73% of the R-value people think they are paying for. This is a particular problem for metal-framed wall systems and is recognized as "thermal bridging."[1] Homogenous constructions like log walls and massive earth wall systems appear to provide closer relationships between predicted and delivered wall performance. Thermal massive walls tend to be climate-specific in their function to reduce the heat flow through building sections, however in moderate to hot climates they do create longer time-constants for such heat flows. R- and U-values describe a rate at which heat passes through a wall ONLY after it has achieved a steady-state condition or the state when heat energy is passing continuously from one side of the wall to the other side at a constant rate. What is not taken into account and yet is critically important when assessing walls constructed with compressed earth blocks is the heat capacity of the wall itself. Massive walls have the ability to absorb, store and release heat. That heat is either generated inside a structure or absorbed from solar energy outside the structure. The heat capacity or heat storage capability determines the length of time required before a steady state of heat flow is achieved. The higher the heat capacity of the wall, the longer the time period it will take for heat flow to reach a steady state condition. In other words, the time required for heat to pass through a massive wall will depend on the resistance (R-value) of the material but also on the heat capacity of the wall itself. In massive walls of adequate thickness and sufficient R-values, normal daily fluctuations in outside temperatures never allow much heat to pass through the wall in a steady state.[2] Massive earth walls are neither great thermal insulators OR thermal conductors but due to their heat storage capability fall somewhere between both. Unlike many modern materials, the heat capacity of earth walls causes them to behave as a reservoir for heat or cold and therefore the wall becomes a buffer between the outside and inside temperatures, slowing down the flow of heat from within in colder areas, or from without in hotter climates. This is known as the “flywheel” effect. Heat loss is often calculated by the following formula: Q = U * A where Q is the amount of heat loss in BTU’s per hour per degree Fahrenheit, U is the inverse of the wall’s resistance to thermal energy and is in units of BTU’s per hour per square foot – degrees Fahrenheit, and A is the area of the wall itself in square feet. According to the Portland Cement Association’s (PCA) engineering bulletin[3] the mass of a wall improves its thermal performance. According to the study, solar radiation adds heat energy to mass walls even in the winter (a passive solar effect) thereby slowing heat loss. Therefore the PCA recommended that the above formula be modified to include a multiplying factor “M” to account for a wall’s heat capacity. The M factor is determined by the total of winter degree days, a calculation that assesses the temperature conditions by location and determines when those conditions will disallow a wall to achieve a steady state condition, thereby slowing heat loss. Taking into account the heat capacity of a wall, the calculation for heat loss would be written: Q = M * U * A Based on real data, this multiplying factor M gives a more accurate assessment of the heat loss of a mass wall and effectively reduces the heat loss by as much as 25% in moderate climate areas. Massive walls will not lose as much heat as non-massive walls, all other things being equal. Typical earth walls (12” in thickness) have a U-value of about 0.2[4] when their mass is not taken into account and the U-value decreases to 0.169 when their heat capacity is considered, a significant difference.[5] In conclusion, thermal assessments of CEB walls must consider heat capacity as well as climate conditions to gain a more accurate appraisal of a massive earth wall’s performance. Evaluating Compressed Earth Block (CEB) walls and Building Codes Currently, the only complete National building codes dealing specifically with Compressed Earth Blocks (CEBs) are found in Germany and New Zealand (see below). The non-profit organization CRATerre, located in Grenoble, France, specializing in earth construction, is now developing CEB codes for the government of France and expects completion in 2002. Other national texts available on guidelines and standards around the world are listed below: United States: the National Bureau of Standards published several documents in the 1940’s, the U.S. Dept. of Interior Building and Indian Affairs and various Uniform Building Code (UBC) Standards were published nationally in the 1970’s and modified for the different states of Texas, New Mexico, Arizona, Utah, California and Colorado. These codes were comprised of adobe codes that were developed for hand-made adobes. Specific codes pertaining to CEB construction currently do not exist in the U.S. However, many structures have been built by applying relevant UBC codes for “low strength masonry” that were originally designed for adobe. Copies of pertinent U. S. codes can be viewed on the internet at: New Mexico - http://www.earthbuilding.com/nm-adobe-code.html California - http://www.earthbuilding.com/san-diego-adobe-code.html Typically in the U.S. when a builder attempts to build with earth blocks, he must provide copies of the codes already developed by other states in order to obtain approval. Most building inspectors will “adapt” UBC code from another state for a newly introduced material such as CEB. In seismic areas, only the California codes are applicable, and again, were designed for traditional adobe construction. Australia: a publication in 1952 by G. F. Middleton described a code of practice for earth construction and was regularly republished. In addition the National Building Technology Centre brought out a revised edition in 1987. In 1995 A.W. Page from the Dept. of Civil engineering and Surveying, University of Newcastle published “Unreinforced Masonry Structures – An Australian Overview”. Germany: The DIN norms for building with earth were published from 1944 to 1956. Several texts were integrated into national documents relating to technical building controls. Several books and technical notes on building with earth have become reference documents in their field. Recently, Germany published their “Earth Construction Standards” (in German only) that can be ordered at: http://www.dachverband-lehm.de/. Peru: The official “Itintec” norms for earthquake resistant buildings of adobe blocks has been integrated into the “Reglamento Nacional de construcciones”. Ivory Coast: Published in 1980, was the “Recommendations for design and construction of low-cost buildings in soil cement” by LBTP (the Building and Public Works Laboratory) in Abidjan. Morocco: Numerous technical documents have been published by the Ministry of the Interior and the Public Research and Testing Laboratory (LPEE) and are currently being updated by the Technical Building Control Department. India: Specifications on stabilized earth blocks were published by the Indian Standards Institute in 1960 and more recently guidelines were published (1994) on “Improving Earthquake Resistance of Low Strength Masonry Buildings” by the Bureau of Indian Standards in New Delhi. South Africa: The South African Board of Standards or SABS controls new construction and alternative building techniques in South Africa. Various publications have been produced on earth construction. However no means exist to apply or enforce codes effectively in the rural areas. They do however require qualification of new building methods if those methods are to be used in urban environments. In the rural environments, many alternative building methods are used without formal SABS approval. The Dept. of Agricultural Technical Services wrote the “Farm-Made Bricks and Blocks for Buildings” publication in 1973. New Zealand Standards: The New Zealand Standards for earth buildings are new publications, first issued in 1998. These specific codes are an adjunct to the existing National building standards for the country. The codes were written in three (3) parts: 1. NZS 4297 – Engineering Design of Earth Buildings – this first document is a reference dictionary for the following two publications. It contains the definition of terms, formulas, notations, limits and parameters necessary to use and interpret the actual codes. It is a reference document for support. 2. NZS 4298 – Materials and Workmanship for Earth Buildings – this publication contains the codes relating to earth materials – their creation and use in earth construction. It also helps to define performance criteria in earth buildings such as wind load and seismic resistance. 3. NZS 4299 – Earth Buildings not requiring Specific Design – this final document gives great specificity of requirements related to structural issues. Footings, walls, diaphragms, bond beams, lintels, wall openings and control joints are all defined and explained in great detail. Codes, and more importantly, code enforcement is almost non-existent in many of the rural areas of third world countries. All actual codes are available from the respective countries but have to be purchased. Finding the Right Soil Soil Basics Soils originate from the weathering of bed rock - that includes physical weathering, freezing/thawing, erosion due to movement by water & winds - chemical weathering from plants and animals and movement of soluble elements through ground water. Laboratory testing obviously gives the most accurate results of soils analysis. However this is expensive and requires access to a lab. It is the most accurate method of determining things such as the grain size distribution and the percentage of the mineral constituents. This is done for example, by accurate measuring and weighing of samples and using 1) sieves for the coarser materials and 2) sedimentation for the finer particles. The main thing to understand about soils is this: The rock, gravel, sand and silt make up what is known as the “skeleton” of the soil. These materials are inert, that is, they are not altered by moisture and they don’t expand or contract. The quantities of these materials is measured based on how much of each material passes through a particular size sieve, in other words, the size determines the material. For example, sands are considered materials that are larger than .06mm (.0024 inches) and smaller than 2mm (.079 inches). The clay portion is known as the “binder”. It is the component that changes in the presence of moisture and it is too small to sieve so it requires more elaborate methods to measure. We need to know what elements are present in a soil, in what approx. quantity and what the characteristics are in order to evaluate a soil for block making. The clay types found most often are - Kaolinite, the most common clay and fortunately the least expansive. Part of that reason is that there are fewer surfaces to “absorb” water. Illite, more expansive than kaolinite but still quite stable Montmorillinite a very common clay but also` very expansive. We essentially need to know the clay’s characteristics: - whether it is expansive, stable, unstable. The Swedish scientist Atterberg developed the Atterberg limits - that is the liquid limit and plastic limit of the soil, measuring the water content percentage on the boundary between the liquid and plastic stage. The Casagrande device is what is used to determine the liquid limit. Therefore to know a soil, we must determine its skeleton and its binder, their quantities and characteristics. In the presence of moisture, soils change their state, from dry to humid, from humid to plastic, from plastic to liquid. An entire science has developed to measure these transitions and once known using laboratory equipment, we can assign what is known as the plasticity index. This tells us the characteristics of the soil - expansiveness, cohesion qualities and ultimately whether that soil will make a good candidate for compressed earth blocks and if not, what we must do to modify the soil. However, because lab testing is not an option in many areas, we also need simple field test methods to evaluate soils. One of the first important tests is again, to determine what sorts of grains make up our soil and how do those grains vary in size? Do we have small & large gravels? What about sand? Is it coarse or fine grained? And is there a lot of silt? And what are the quantities? Is the soil mostly sand? Or maybe it’s mostly gravels. So the first tests are to get an idea about grain size and distribution. Secondly, we need to know how plastic, how cohesive the soil is. Will it hold together when we make a block? Can it be molded? How strong will it be? Can it be compacted and if so, how strong is it? And a VERY important question, will it shrink when it dries. Because if it shrinks, it will expand again if it gets wet and break our wall. And what about the chemistry? Is it full of organic material? What about the salt content? What about lime? And based on the geology of the area can we determine anything about this soil? Volcanoes, lots of pumice, no clay, etc. Finding the Right Soil. Soil Testing Testing soil samples: When finding new sources of soils, you might try and locate a commercial gravel/sand/dirt yard, talk to the workers in the yard, discuss with them what you are looking for, a soil that is mainly small gravel (approx. 10%), coarse and fine sand (approx. 50 to 70%) and the rest clay. Depending on the type of clay (highly expansive or not) the clay percentage could be higher but you shouldn't go much lower than 20%. Get several samples of different mixes if available and before leaving the yard, do a few simple tests. Ultimately you would want to make several blocks in the machine from the samples, but transporting sizable samples to the machine isn't always an option so you need to know if you are in the ball park with the soils. So, take a couple of gallons of water with you and do the following: Take a small amount of soil in the cup of your hand and begin pouring a small stream of water under a faucet or have someone pour it from a bottle slowly but continuously, and slowly allow the clay & silts to escape as they go into solution and flow over the edges of your hand, stirring with your finger. The trick is to keep the visible particles of sand & gravel in your hand while washing away the small clay and silt particles. Once the small stuff is gone you can see the "skeleton" of the soil, the inert portions that make up the backbone of the soil and you also get a sense of the quantity of sands and gravels from the total sample. What we want ideally is a good distribution of grain sizes. Small to smaller pieces of gravel, coarse to fine grains of sand. Just like concrete, we need backbone, interlocking particles of various sizes that lock together like a puzzle. The clay is the “cement” and with a good backbone/skeleton the block will be strong and resistant. Notice when you wash your hands after handling the soil if it washes off easily or is "sticky" because it contains a lot of clay. We need a portion to be clay not just silt. Silt won't leave much of a residue when you wash your hands. Notice the smell of the soil when wet. If it contains a lot of organics, it will have a distinct "musty" smell. We don't want organics in the soil. It should be subsoil, taken from below the topsoil layer. Take each sample and add water to make the sample plastic, but not too wet. You need enough soil to make a "cigar" about 20cm long. Once you have a more or less uniform cigar, place it on a flat surface (you can use your hand and arm but a table or piece of plywood would be better) and slowly push it over the edge, starting at one end. If the soil contains enough clay to be cohesive, the cigar will bend and yet stay together when more than5cm is hanging freely over the edge. If the soil contains too much clay and not enough sand, more than 15cm of cigar will hang over without breaking. We are trying to find a soil that has good cohesion. This test gives us a good indication of whether we have enough clay to make good blocks. When we get between 5cm and 15cm hanging without breaking that's usually a soil that will make block. Moisten the soil if necessary. Feel the soil. Clump it together in your hand. Does it form into a clod easily? Does it compact? Can you form into a ball without cracking when it is moist? Clay makes soils pliable and plastic. Silt on the other hand looks like clay but doesn't really "bind" the soil together very well. When a soil is silty, it tends to be much more crumbly and less plastic. It doesn't have good cohesion. At the same time we NEED various grains of gravel & sand, or at least various sizes of sand, not just clay. So use your judgment and if a soil sample looks like it has the basic ingredients we need, then try the following. Be sure that the soil is moist enough - it should feel like a newly tilled garden or maybe little drier - if not, mix by piling the soil into cone, then moving the pile while sprinkling water. Then once entirely moved, move again, sprinkling with water while moving with shovels. You should move the pile twice to insure a good mix. "Pour" each shovelful over the previous to maximize the mix and to get a homogeneous mixture - once mixed, let the moisture "activate" the clay in the soil by letting the moisture get absorbed for at least 30 minutes. This is true for tests that require moisture. Get the soil wetted but let it sit for a time, 30 minutes or more. More is better. It takes awhile for clay to absorb moisture and to activate and become "sticky". After the soil is wetted and activated, put at least 1/2 a bucket (or more) of the mixed soil into an open container, like a metal bucket, or better yet, like an open adobe mold. Ideally without the machine you could make up a mold with 2x4's that is the dimension of a Block Press block. That is, 8" x 12" x 4". Put in an inch or so of soil and "compress" that soil as best you can using the blunt end of a 2x4 or something similar.Add soil in increments compressing it each time. Identify the results or keep a log so that you can correlate the blocks with the sample. Leave the sample in the mold until it dries unless you can remove it after compressing it without breaking it (you can put a piece of plywood on the top of the mold and flip it over like a cake pan). Stack the "block" so that it can air dry [all faces mostly exposed] and definitely keep it out of direct sun. Handle new blocks gently, some soils will be fragile initially but when dried become quite durable. Be sure to ask the workers at the yard if they can mix moisture [if needed] into the soil as well as the components of the soil such as clay and sand. You need to know the pricing and cost for transport to the building site and you also need to know that all the soil will be homogeneous and the same mix, consistent. Before starting out on this search, make several rings by sawing a 3 or 4 inch diameter PVC pipe into cross sectional rings, one inch wide. After you obtain the samples, take each sample, add water to it until it becomes quite plastic (not a liquid but wet enough to deform easily with very little cracking). Set the ring on a flat surface, press the plastic soil sample into the ring until you create an even biscuit, flat on both sides, no air pockets in the sample. Leave the sample in the ring and repeat this with each sample. Let these dry entirely, usually 3 days at least. Notice the amount of shrinkage away from the ring when the sample is dry. Then try and break the biscuit by bending it. If it is difficult to break it probably has good clay binding it together. If it is easy, it probably doesn't have enough clay and won't make good block. If it shrinks a great deal, that means the clay is very active and will cause problems unless we add more "skeleton" in the form of sands. Ideally we want a very strong biscuit that is very hard to break and that only shrinks slightly away from the PVC ring. As the biscuit dries it may also crack if there is too much clay and not enough skeleton. If that happens, you might try another mix, adding more coarse sand to the soil and repeat making the biscuit. Adding more skeleton will reduce the cracking and make a stronger biscuit. The best test, of course, is actually making blocks with the 520 Block Press but you'll have to improvise. We want blocks that don't crack when drying and are strong. We can live with blocks that aren't perfect; edges slightly crumbly, corners break off. But we don't want serious cracking. That means cracks that are penetrating the block and weakening it. Surface cracking or spider cracking is OK, although a little more sand will usually eliminate it. You can also get undesired cracking if the blocks are dried unevenly or too fast. Placing them in direct sun or on top of each other so that some surfaces are not drying as fast as others can cause cracking as the moisture tries to escape. Once the blocks are dry (touch them to your cheek and see if they feel damp or "cold", if so they are still somewhat moist) test their strength by placing two blocks on the ground and "bridging" a third block across them so that it is supported, two inches on each end but not in the middle. Then stand on the block. It should easily support your weight without breaking. You can also do a sedimentation test with a jar to help determine the approx. ratios of components. Place a measured amount of soil into a jar, along with a little salt to speed things up. In other words, notice how much soil is in the jar before proceeding. That way, if the clays expand after wetting, you can tell the difference in volume. Slowly pour water into the jar until the jar is nearly full. If the water percolates very slowly to the bottom of the jar, it can indicate a lot of clay although it can also be due to a lot of fine silts. If the water percolates quickly, it usually indicates much less clay or none at all. Shake the jar vigorously a few minutes and then let it set to activate the clay. Then shake again and set the jar on a flat surface and wait several hours for the soil to settle out. Small rocks & gravel will settle to the bottom first, followed by coarse & fine sands, then silts, and finally any clay. Organic material will often float on top. By simple observation of the stratified layers, you can determine the approximate ratios of most of the components. However, the other tests are necessary to determine a more accurate picture of the clay and whether it is expansive or not. Good block-making soil requires 20% to 40% clay to bond the soil together, with 60% to 70% sands & gravels making up the remaining bulk. That's it. Once you’ve had some experience, the process of identifying soils becomes easier and easier as you get to know the basic characteristics of your local soils. Evaluating Compressed Earth Block (CEB) walls and Structural Performance In the world of earth wall construction, compressed earth blocks are a relatively new phenomenon. Earth walls have been built for thousands of years in a variety of forms in nearly every region of the world but machine-compressed earth blocks arrived on the scene only a few decades ago. One of the oldest earthen materials still in use worldwide is adobe blocks. These blocks are made from mud formed in molds, dried in the sun and stacked into walls. Often the walls are left exposed or covered with a natural plaster and are usually quite thick, ranging from ten to twenty four inches. Due to the widespread use of traditional adobe, various building methods utilizing these blocks have been studied in many parts of the world for structural integrity & performance, especially in seismic and high wind areas. This is a significant fact for modern builders using compressed earth blocks because CEBs originated from traditional sun-dried adobes and have many characteristics in common, both in the material itself as well as the building techniques used when construct with them. More importantly, knowledge that has developed about adobe construction over hundreds of years is often applicable to CEBs and their use. More specific research on CEB construction is needed but many basic ideas from traditional adobe construction are valuable for the modern builder of compressed earth block structures. This report lists and briefly summarizes some of the more important conclusions of research that have been reached on earth wall construction to assist builders in their efforts to build safely with compressed earth blocks. First, what are the similarities and differences between sun-dried adobes and compressed earth blocks? Traditional Adobes Sun-dried adobes are just that. Mud dried slowly in the sun. The clay particles have time to align themselves and bond chemically with each other. This type of bonding creates a block with a compressive strength of about 300 PSI and one that is naturally resistant to weathering. Surprisingly, traditional adobes are much more resistant to erosion from moisture than compressed blocks made of the same materials, although they are not as strong. The strength of adobe block also limits the strength of the wall it comprises. In an effort to increase the wall strength, most adobe walls are built thick. Adobe walls usually need protection, by design, using roof overhangs and by plasters that add water resistance to the wall. There are many variations and many additives but both types of blocks are essentially comprised of natural soils. However, the method of their creation results in distinct differences. CEBs Compressed earth blocks are bonded by pressure. As with adobes, the binding ingredient is also clay, but the particles are “welded” together with high pressure resulting in a block that has a much higher compressive strength than a traditional adobe. However the bond is not as resistant to moisture unless additional ingredients are added to help waterproof the block. Many variations have been developed with CEBs by adding various binders and stabilizers. The most common is Portland cement. When CEBs are stabilized with our soil additives, the results are actually more similar to a fired brick in appearance and characteristics. That includes the brick’s structural compressive strength. Stabilized CEBs are often mortared together similar to blocks and bricks using a stabilized mortar. Mortar is optional above grade with our exclusive interlocking design. The techniques of construction employed by a builder using earth blocks, either adobes or CEBs, are extremely important to the structural integrity of the completed building. In areas where traditional adobe materials have been used for hundreds of years, places such as Santiago Chile, it is not uncommon to find adobe buildings that have withstood many earthquakes and are centuries old and at the same time find adobe houses that collapse every time there is a large earthquake. If both were constructed with adobe blocks, how is this possible? The difference is the construction method. Studies have been conducted on many aspects of adobe construction in an effort to determine what is safe and what can be improved. Many of the conclusions of those studies have been incorporated into various building codes & policies in an effort to “standardize” earth block construction methods and create safer structures. In the United States, compressed earth blocks have been accepted as equivalent to or stronger than traditional adobe blocks and building codes that were designed for adobes are now being applied to CEB construction. Therefore, realizing the research behind those codes gives a common sense approach to building safely with compressed earth blocks. Summarizing structural studies, some basic criteria become evident for safe earth block construction. The Uniform Building Code (UBC) of the U.S. requires that all elements within the seismic zones of 2, 3 or 4 (such as southern California) must qualify as reinforced masonry. Because standard rebar reinforcement used in concrete block construction isn’t a practical method with solid earth blocks, other methods of strengthening are required. Listed below are many, though certainly not all of the methods employed to insure safe construction: 1. Thicker walls are better.[1] A minimum ratio of wall thickness to height is required for example, in the county of San Diego, California, seismic zone 4, the highest risk seismic zone. For every inch of wall thickness a builder can go up eight inches in height. Therefore by code, a twelve-inch thick wall is the minimum for an eight foot high wall made from unstabilized earth blocks in a high seismic area.[2] 2. All structures in seismic zones 2, 3, and 4 are limited to one story, but we are going through siesmic testing to support multi-story buildings.[3] 3. A continuous bond beam should be an integral part of an earth wall. Designed to cap the walls and add additional strength, the beam also acts as a diaphragm and equalizes the loads of the roofing system. Its dimensions and design are usually defined by local codes.[4] 4. The use of stucco wire (sometimes referred to as chicken wire) to wrap the walls both inside and out adds enormous lateral strength. United States codes do not require the use of stucco wire but studies have shown it to be one of the most effective methods of wall strengthening in seismic regions.[5] 5. The use of strong plasters adds wall strength and protects the blocks from water & mechanical damage.[6] 6. The strength and durability of the blocks should be tested to insure quality block making methods and stabilizing blocks reduces a structure’s vulnerability to seismic events.[7] 7. Correct placement of windows and doors is necessary to reduce the weakening of the wall. Openings too close to corners or to each other can cause structural weakness.[8] 8. The use of buttresses at wall intersections and corners as well as reinforcement on long spans adds wall strength.[9] Many local techniques have been developed in areas that have utilized earth block construction traditionally. However, some methods are not easily exportable to other regions due to cultural differences or building practices. For example recent application of the use of bamboo as a reinforcing agent has not found wide acceptance here in the United States, although preliminary data indicates when properly cured bamboo is stronger than steel. Each geographic area needs to be assessed by qualified individuals based on local conditions, materials, building practices, codes, policies, cultural attitudes and economies. Based on such assessments, designs can be developed that “fit” the region and insure acceptance as well as meet safety requirements.