Hemp Crete And Other Stuff… ENGR 45, SRJC Fall 2010 GianCarlo Santa Cruz Doug Howe Nick Fryer Bryan Cote HempCrete and Concrete Objective: Our project was to determine the compressive strength of HempCrete compared to other aggregate materials used in concrete. •Concrete and its properties. •Hemp and its qualities. •Why Hemp is a viable and used as an alternative aggregate. •Hemp applications. •Making HempCrete. •Testing it against traditional methods. •Results. •Conclusion. What’s Concrete • Concrete is a composite material consisting of cement (commonly Portland Cement), aggregate (rocks/sand), water, and chemical admixtures • Concrete solidifies and hardens through the chemical process of hydration, where the water reacts with the cement, binding the other components together Concrete Properties • Has very high compressive strength, but low tensile strength • All concrete structures will crack to some extent, due to shrinkage and tension Concrete Properties • Very low coefficient of thermal expansion, shrinks as it matures • Its elasticity is relatively constant at low stress levels but it starts decreasing at higher stress levels as cracks develop. •Having reinforced concrete increases overall tensile strength by adding steel reinforcements bars, steel fibers, glass fibers or plastic fibers to carry tensile loads. History of Concrete • The Egyptians used lime and gypsum cement, possibly in the pyramids • Widespread use of Roman concrete, made of quicklime and volcanic rock • Revolutionized building by allowing larger and more complex structures • Absence of steel reinforcement limited tensile strength • Today concrete is used more than any other man-made material in the world Fun Facts What is the Most Consumed Substance on the Planet? Concrete, produced at an estimated rate of 7 billion cubic yards per year, is the second most widely consumed substance on Earth, after Water. Cement Usage: The United States uses 891 lbs. of cement per person each year. California uses 860 lbs and Nevada uses 2,170 lbs. per person each year! Source: US Census 2000 & USGS Mineral Survey. Pop Quiz: For a bag of M&M’s What is the largest single public works project in the history of the United States, containing 3.25 million cubic yards of concrete, which is enough to pave a two-lane highway from San Francisco to New York. Theory Behind HempCrete • The mixture of sand, cement, and hemp to create an alternative form of concrete. • Two main types of HempCrete: -Hemp bast fiber-greater structural strength -Pith/hurds-less predominant in textiles • Hemp fiber increases tensile and compressive strengths, reduces shrinkage and cracking, similar to rebar or fiberglass. • Hemp hurds are also uncommonly rich in silica. • When mixed with lime, hemp hurds change from a organic product to a mineral. As a mineral state it is often referred to as hemp stone. • Several hundred houses have been built in Europe using this material. Hemp vs. Marijuana Male Plant Female Plant •Buds grown for smoking •Unfortunately, does not contain structural hemp What We Look For •Anatomical substructure reveals plant sex and consequential structural relevance •Usually cultivated for obtaining seeds, however, the presence of this plant will make undesired female bud. •This is where we obtain textile hemp. Hemp Up Close •Longer bast used for structural applications. •Outer bark and inner hurds, shorter and courser in nature, not usually used for textiles. •The desired bast can be obtained by lightly shaving the bark away, while shaving down to the core without penetrating the interior. Growing Hemp 1. Plant Description Hemp (Cannabis sativa L.) is an annual herbaceous plant with a slender stem, ranging in height from 4 to 15 feet and a diameter from 1/4" to 3/4". The innermost layer is the pith, surrounded by woody material known as hurds. 2. Soil and Soil Preparation Soils Industrial hemp can be grown on a wide variety of soil types. Hemp prefers a sufficiently deep, well-aerated soil with a pH of 6 or greater Growing Hemp 3. Nutrition To achieve an optimum hemp yield, twice as much nutrient must be available to the crop as will finally be removed from the soil at harvest. A hemp field produces a very large bulk of vegetative material in a short vegetative period. The nitrogen uptake is most intensive the first 6 to 8 weeks, while potassium and in particular phosphorous are needed more during flowering and seed formation. Industrial hemp requires 105 to 130 lbs./acre (120 to 150 kg./ha) nitrogen, 45 to 70 lbs./acre (50 to 80 kg/ha) phosphate and 52 to 70 lbs./acre (60 to 80 kg/ha) potash. (vegetation and flowering) Growing Hemp 4. Growing Conditions Hemp prefers a mild climate, humid atmosphere, and a rainfall of at least 25-30 inches per year. Good soil moisture is required for seed germination and until the young plants are well established. • There are two types of industrial hemp based on their use. • fiber cultivars - with long stalks and little branching; (shown to the right) • seed cultivars - with shorter stalks, larger seed heads and may have numerous branches (seed contains 30 - 35% oil). (shown to the left) Why It is a Viable Alternative • Renewable resource. • Applied across many fields. • Readily grown. • “Industrial hemp” that were bred over time for industrial uses such as fuel, fiber, paper, seed, food, oil, etc. • Recreational Purposes Current Global Hemp Usage • Countries where hemp is grown as an agricultural crop, the police have experienced the criminal burdens that other countries face. In fact, there are over 30 powerful nations on the planet currently growing industrial hemp. – These include Canada, Australia, England, France, Germany, Austria, Spain, Russia, and China. • These previous successes explain why legislation is pending to deregulate industrial hemp and/or allow scientific study by state universities is pending or passed in over 20 states: – Bills Passed: ND, HI, MN, IL, MD -- Resolutions Passed: AK, CA, KY, MT, VA, VT Legislation In Process: SD, IA, ME, NH, NM, OR, TN -Voter Initiatives: AK, CO, MI Real World Application • Inspirational HempCrete • Buildings account for thirty-eight percent of the CO2 emissions in the U.S., according to the U.S. Green Building Council, and demand for carbon neutral and/or zero footprint buildings is at an all-time high. Now there is a new building material that is not just carbon neutral, but is actually carbon negative. Developed by U.K.-based Lhoist Group, Tradical® Hemcrete® is a bio-composite, thermal walling material made from hemp, lime and water. What makes it carbon negative? There is more CO2 locked-up in the process of growing and harvesting of the hemp than is released in the production of the lime binder. Of course the equation is more complicated than that, but Hemcrete® is still an amazing new technology that could Real World Application • Good looking, environmentally friendly and 100% recyclable, Hemcrete® is as versatile as it is sustainable. It can be used in a mindboggling array of applications from roof insulation to wall construction to flooring. Hemcrete® is waterproof, fireproof, insulates well, does not rot [when used above ground] and is completely recyclable. In fact, the manufacturers say that demolished Hemcrete® walls can actually be used as fertilizer! Making HempCrete • Obtaining hemp • Extraction of hemp • Making of the base mortar • Determining the Ratio of mortar to aggregate • Construction of the test samples • Testing the samples Traditional Means of Obtaining Bast •Bacterial Removal , through retting, of outer bark and inner hurds. •Done by retting using bacteria infused solutions. •Retting through chemicals. •Dew retting: leaving cut stalks in humid fields; this allows the elements to decompose the outer bark and inner hurds. •New techniques use ultrasounds and steam explosion. •After this process, the remaining bast may be separated directly and used in textiles. How We Attempted to Replicate Retting • Since we lack traditional means for retting, we used knives to attain the acquired layer, simulating the process. •By shaving off the bark, and lightly whittling the hemp, we could isolate the bast fibers, without penetrating the core. •What We Want •What We Don’t Want Extraction of Hemp Conflict: Nerds w/ Knives Determining the Ratio of Water To Mixture • Bag says 4 qts for every 60 lbs of mortar, let’s make it friendly tho: • 60 lbs mortar = 27.2 kg mortar • Mass of 1 cup of mortar = 383.2 g • 1 quart = 4 cups • Ratio cups/grams = 5.88 x10-4 • Water/Cup Mortar = .225 water/cup • For simplicity, we made an excess of concrete for the form(s) using 10 cups of mortar and 2.5 cups of water to ensure adequate saturation. Determining the Volumetric Ratio Between Unmixed Mortar and Hardened Mortar •In order to ascertain a specific volumetric ratio between the mortar and the aggregate, we first had to obtain a ratio in between unmixed mortar and its final volume when cured. •After using one cup of mortar and the predetermined water, we constructed a test form. •After curing we placed the test piece into a graduated container and measured the water displacement, this was 215 ml which is equivalent to its volume of 215 cm3. •We also calculated the volume mathematically by measuring the height (4.572 cm) and radius (3.81 cm) and inputting them into π(r)2h which equals 208.5 cm3. •From this we use the average volume of 211.75 cm3. Determining Ratio of Aggregates Synthetic Fiber Hemp Fiber •We first created an insulated piston using duct tape and a can. •Without aggregate, we inserted the can into the form and marked off the initial. •We then packed aggregate inside the form until the height difference was 4.6 cm-packing was necessary to ensure adequate volumetric distribution. •Using the 1 part aggregate, we added it to 10 parts mortar. Cut Metal Shavings Making the Forms Initial Attempt Using a 4-in diameter pipe and lots of vegetable oil… It gets stuck after hardening. Solution By using postal tubes, we cut disposable forms that can be pulled off the samples, rather than trying to pull the sample from the form. Mixing the Samples Curing and Removal of Samples •Cardboard shipping tubes proved far easier to remove than plastic tube. •Just peel the cardboard away and pull sample out. •This also negates the risk for any further knife injuries! Other Tests In addition to testing HempCrete, we also tested the following mixes: -Mortar w/ Steel Wool Aggregate -Mortar w/ Fiberglass Aggregate -Standard Control Mortar Mix -Standard Concrete Mix -Different Ratios of Mortar & Concrete Testing the Samples Control Metal Fiber Glass Hemp Results Compressive Strength of Concrete Max Compressive Strength (psi) 10000 1000 100 10 Max Compressive Strength (psi) 100000 Volume Percent Mortar 1 Samples The “What” Moment • At one point in our experiment, we did actually create a sample that maxed out the 250,000 lb testing equipment! • By crushing random things, we found that a sample stuck in a plastic tube was capable of withstanding the 125 ton force! Conclusion •By far, the combination of a soft and hard medium, although incidentally, provided the best results. •We can also conclude that out of all the aggregate, the metal shavings were the strongest, which is understandable when we consider its applications in industrial and commercial construction. •Despite hemp’s poor performance, we observed that it’s max load was similar to that of fiber glass. Closing Statements • Although hemp does not increase structural strength by what we had assumed, it does, however, exhibit structural properties similar to that of fiber glass. – This is important because we now know that Hemp, being carbon negative and a renewable resource, is a viable alternative aggregate, while maintaining some structural strength. • Our experiments also showed how a soft medium combined with a hard medium, will have a significant increase in structural strength, thus providing the next ENGR 45 classes with future potential projects. References – http://en.wikipedia.org/wiki/Concrete – http://en.wikipedia.org/wiki/Hempcrete – http://www.limetechnology.co.uk/index.htm?pages/hemcrete.php – http://www.naturalbuildingcompany.com/nbm/hemp – http://www.cement.org/basics/index.asp – http://www.binhaitimes.com/hemp.html – http://www.onetruepants.com/blog/hemp-bast-fibers-getting-to-the-core-of-it/ – http://www.legaltripz.com/Pics/big_bud_marijuana.jpg – http://www.gardenscure.com/420/attachments/growth/130639d1117126967-male-female-first-plant-grown-malewpreflwr.jpg – http://fc03.deviantart.net/fs32/f/2008/233/d/e/Marijuana_Leaf_v2_REQUEST_by_Holly6669666.jpg – http://www.naihc.org/hemp_information/hemp_defined.html – http://arahanteco.blogspot.com/ – http://www.google.com/imgres?imgurl=http://images.clipartof.com/small/13182-Blue-Man-Flexing-His-Muscles-Clipart-Illustration .jpg&imgrefurl=http://www.clipartof.com/details/clipart/13182.html&usg=__rmiRKw5aZA1pfJDYdX0N3ITicLo=&h=450&w=367&sz= 45&hl=en&start=5&zoom=1&itbs=1&tbnid=lppEYHNckAkwrM:&tbnh=127&tbnw=104&prev=/images?q=man+flexing&hl=en&gbv=2& –http://www.google.com/imgres?imgurl=http://2.bp.blogspot.com/_lwJFvxkUlUM/TPKBsNBBduI/AAAAAAAAAYk/uQrTPZe2jRs/s16 00/tension1.jpg &imgrefurl=http://rayitoajua.blogspot.com/&usg=__pUjuvGh4icIQ4M4Ok4EUdn12bs=&h=411&w=393&sz=46&hl=en&start=23&zoom=1&itbs=1&tbnid= Qw1X52dvOwtJjM:&tbnh=125&tbnw=120&prev=/images?q=tension&start=20&hl=en&sa=N&gbv=2&ndsp=20&tbs=isch:1 –http://masonry.kpmindustries.com/images/products/BlockMortarBag.jpg –http://www.hort.purdue.edu/newcrop/ncnu02/v5-284.html –http://c.photoshelter.com/img-get/I0000bjepLYfnGgM/s –http://www.hort.purdue.edu/newcrop/ncnu02/images/hemp01.gif –http://www.uwsp.edu/geo/faculty/ritter/images/biosphere/soils/ph.jpg –http://www.fertilizer101.org/images/ch2/Fertilizer_by_the_Numbers_Ch2.jpg –http://www.cannabis.at/forum/bilder/data/516/white-rhino-marijuana-1.jpg –http://blog.norml.org/wp-content/uploads/2009/12/hemp-field.jpg –http://www.busyboo.com/wp-content/uploads/green-hemp-house-2.jpg –http://abetter-design.com/wp-content/uploads/2010/12/Thehousemadeofhemp_1_abetterdesign.com_1.jpg –http://www.hemp.com/wp-content/uploads/2010/09/hempcrete.jpg –http://stonerschematics.com/wp-content/uploads/2010/11/hemp_brick.jpg • Special thanks to all the California growers who made this possible!!! • Only two humans were harmed in the making of this project……..