Grantee Research Project Results
Final Report: Rice Hulls as Alternative Building (RHAB) Project
EPA Grant Number: SU835095Title: Rice Hulls as Alternative Building (RHAB) Project
Investigators: Williams, Michael , Anguiano, Maria Elena , Feher, Stephen I. , Rhodes, Bryce , Flores, Jesus , Vazquez, Luis , Nava, Robert
Institution: Butte College , Sustainable Community Development Institute
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2011 through August 14, 2012
Project Amount: $14,475
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2011) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Chemical Safety , P3 Awards , Sustainable and Healthy Communities
Objective:
Butte‐Glenn Community College District (Butte College) is a public, two‐year institution of higher education that enrolls 14,000 students. Our campus is rurally isolated, and we are situated half way between San Francisco and the Oregon border, in the fertile upper reaches of the Sacramento Valley. We are considered a leader in fostering understanding of sustainability in all our curriculum and college activities (Blanchet 2008). Our community college district serves two counties: Butte, equivalent in geographic size to the state of Delaware; and Glenn, equal in size to Rhode Island. Our economy is agriculture based, and we are experiencing an explosive growth of first generation Hispanic students, and other low income minorities including African‐American, Sikh, and Hmong. Our enrollments continue to surge because of chromic high unemployment in California, 9.3 %, and 12.9 % in Butte County and even higher, 16.9% in Glenn County. Loss of agricultural jobs due to mechanization is creating structural unemployment in our region. Many of our students want to reverse the situation facing their parents and grandparents, by achieving higher aspirations in Science, Technology, Engineering, and Mathematics (STEM) fields. Our successful Math Engineering Science Achievement (MESA) program has achieved this goal for many of our first generation, low‐income students. We have been able to build upon the success of the MESA Program’s Student Research Projects through the Environmental Protection Agency’s People, Prosperity and the Planet (EPA P3) Program. Our intent is to leverage our MESA student research projects to achieve a clear transfer path to four‐year colleges and universities for them. With this in mind, we are pleased to submit to EPA our student‐led project, “Rice Hulls as Alternative Building” (RHAB), for Productive Use of Agricultural Waste Report and Phase II proposal. Of the 45 2011-12 awards made in the EPA P3 Phase l grants to colleges and universities, Butte College was the only community college awarded.
Accomplishing the goals of the Rice Hulls as Alternative Building” (RHAB) project would impact the communities affected by the rice growing areas locally and globally. The objective of this project is to provide an appropriate, environmentally acceptable disposal of agricultural waste, in this case, rice hulls which are left behind in huge quantities after harvesting and processing rice produced in Northern California and other rice producing areas in the United States and around the World. This is to be done by the development of structural insulating panels (SIPs) for use in residential and commercial building construction utilizing rice hulls as their primary raw material. Normally, structural insulating panels are made of a layer of Styrofoam panel sandwiched between two sheets of plywood. We plan to modify this concept to make use of rice hulls.
Potential economic benefits resulting from this project could be very large if the development effort is successful. The supply of rice hulls, the principal raw material of the proposed RHAB building system, is plentiful in Northern California. The local industry resulting from the manufacturing of the RHAB building system could be a multi-million dollar annual business with a marketing area over the entire western part of the United States. Additional RHAB manufacturing facilities could be established in other rice growing regions, such as the mid-west and southern United States, indeed around the World, because rice is one of the most widely grown agricultural products worldwide.
A potential significant positive environmental and heath impact offered by the project is the reduction of air pollution and emission of greenhouse gases that could be achieved by the worldwide application of the proposed RHAB building system. It could have a huge direct positive impact on the environment, global warming and public health worldwide through the reduction of burning and decomposition of rice hulls, one of the most abundant agricultural waste materials on the Planet. Not only does it provide the farmers an alternative to burning or burying, the method that we plan to use can also provide jobs in manufacturing, reduce the cost of construction, reduce the energy consumption of buildings, reduce the carbon footprint of construction, and increase the fire resistance of buildings. The use of rice hulls in the production of building materials would result in permanent sequestration (encapsulation) of the carbon content of this agricultural waste material. This would contribute to meeting the requirements of the Clean Air Act (CAA). Eventual disposal of these new building materials, after useful building life, in an environmentally suitable manner will be considered in the study.
Summary/Accomplishments (Outputs/Outcomes):
Specimens
Our samples were cast in molds that we made using ordinary construction plywood and
lumber (see Figure 1). We made three different sizes to have a better understanding of the
thermal and mechanical properties. These properties may change depending on dimension. The
process to make a sample starts with the development of the composition of the mix for the
materials specific to that module. The next step is to determine the size of an appropriate mold.
Some calculations are necessary to find the volume of the mold and the amount of each material
needed to fill it to the correct level. Once all the calculations are done, the volume of each
material will be measured using a calibrated container. The next step is to add the materials into
a cement mixer to have a uniform mix of the dry materials. Water is added in small amounts
until the mixed ingredients have reached the right consistency. This is followed by pouring the
mix into the mold and tapping it gently on the edges to eliminate air bubbles. We allowed each
module to dry for one week before removing the sides of the mold. Due to the number of
modules we desired, it was essential to develop a nomenclature and coding system for each
module./p>
Thermal Testing
The procedure used in order to test the thermal properties of our samples is simple. We
used an apparatus designed to model after that described in ASTM Standard C177; The Standard
Test Method for Thermal Conductivity Measurements of the guarded-hot-plate apparatus. This
standard describes a Guarded-Hot-Plate Apparatus that can be constructed from ordinary
construction materials, and is used to find the heat flux through an insulating specimen with
specific geometry. The specific materials used in the construction of our apparatus were
determined in a way that would minimize the heat loss from our system. Data collection was
done via lab devices outside of the apparatus.
The relationship between thermal dynamics and home insulation is when insulating homes we attempt to reduce the amount of energy transfer through walls, ceilings, floors, and windows. Our findings illustrate the differences in heat transfer between samples. In theory, we believed the samples with the largest difference in heat transfer would result in a better thermal insulator. Further statistical analysis of this data set is needed. Our hypothesis from visual inspection was that the thicker the testing panel, the heavier it became. This of course compromises the effective shipping cost of any product. However, this increase in the sample thickness did create larger R values. One aspect we needed to pursue was how to make the samples lighter? This led in an experiment using Styrofoam filler in the module composition.
Mechanical Testing
The next phase in our process was to test the strength of our samples. Because of the
module curing time, only a few have been dry enough to undergo strength testing. From those
that have undergone thermal testing, we selected four specific samples to put through the
strength testing. These four samples, as coded suing Table 1, are: A14II, A146III, A15II, and
A15V. Module A14II contains 50% Rice Hulls and 50% cement. Module A146 contains 33%
rice hulls, 33% cement, and 33% perlite. Module A15II contains 50% Rice Hulls and 50%
gypsum. Module A15V contains 60% Rice Hulls and 40% gypsum.
Conclusions:
The results of our research in Phase I have shown positive results. Thermal testing has confirmed our hypothesis that using rice hulls as an insulator for structural insulated panels for building construction has meaningful value. Mechanical testing shows that our samples compare to current construction materials. There are more elements, however, that must go into the making of a panel for building purposes.
As we move forward in our research we are discovering additional issues we plan to examine, for example: composition of appropriate ingredients in each panel and occurrence of mold in one of our specimens. Additionally, cement is the binder that we feel offers the best results in our rice hull SIPs, however, cement is very dense. As we began to make larger dimensional panels for testing, we found that the panels became too heavy. We have been able to minimize this problem by researching alternative filler ingredients that allow for less cement input. One useful ingredient we found was Styrofoam. We have been able to take used Styrofoam and grind it down using a system we developed, incorporating the ground pieces as an ingredient in our panels. This is just one solution to our panel density issue.
Another solution that we crafted to reduce panel density is an adaptive method already being used in building construction, Rastra (made up of recycled Styrofoam and cement). Rastra, is a method of building wall systems that follows very closely to how cinder blocks are used. The “blocks” are molded in such a way as to allow them to interlock when stacked vertically or butted together horizontally. There are cavities throughout the complete interlocking system that allows for reinforcement bar stabilization. After the re-bar is in place, cement is poured into the wall. The cement cures and the wall system is complete. The “blocks” are often referred to as Insulated Concrete Forms ICF’s).
Supplemental Keywords:
Building Materials, Agricultural Waste, Sustainability, Rice Hulls, Fire Resistance, Styrofoam, Rastra, Thermal Testing and PerformanceRelevant Websites:
Sustainability - Butte College Exit
MESA- Butte College Exit
The Sustainable Community Development Institute (SCDI) Exit
P3 Phase II:
Rice Hulls as Alternative Building (RHAB): Productive Use of Agricultural WasteThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.