2019 Progress Report: Husk-to-Home: A Sustainable Building Material for the Philippines

EPA Grant Number: SV836952
Title: Husk-to-Home: A Sustainable Building Material for the Philippines
Investigators: Tam, Kawai , Rust, Michael , Mathaudhu, Suveen , Truong, Brittany , Long-Le, Viet , Ibrahim, Pavly , Morrison, Christopher , Hwang, Edward
Institution: University of California - Riverside
EPA Project Officer: Page, Angela
Phase: II
Project Period: February 1, 2017 through January 31, 2019 (Extended to January 31, 2021)
Project Period Covered by this Report: February 1, 2019 through January 31,2020
Project Amount: $74,838
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2016) Recipients Lists
Research Category: P3 Awards , Sustainability , P3 Challenge Area - Built Environment


As the effects of climate change continue to grow in severity, the search for environmentally friendly materials, technology, and energy has accelerated. Such materials are not only needed to begin reducing climate change, but are also needed in order to respond to and mitigate the effects of increasingly severe natural disasters on affected communities. While such natural disasters are impossible to prevent, green technology can provide a sustainable and effective solution to disaster mitigation efforts around the world. Husk-to-Home was formed to solve problems encountered by today's traditional home building materials. Temporary shelters and permanent homes built with materials such as lumber all share common weaknesses; they are energy intensive to produce and extremely susceptible to termite damage. This, in turn, costs communities billions each year, and it is estimated that termite damage repair costs $1 and $2 billion in the United States alone [1]. At the same time, countries around the world are constantly disposing of an abundant termite and flame-resistant resource, often in the same regions most severely affected by termite damage. Husk-To-Home's plan is to engineer these region's wasted rice husk and straw into an affordable termite and flame-resistant building material.

Husk-to-Home has designed and is now testing a particle board made from rice husk and rice straw. This board, just like the rice byproducts, is resistant to termite damage and heat while also being sturdy enough to compete with normal siding materials.

Husk-to-Home's main objective is to become a successful non-profit corporation that can alleviate and prevent housing damage and crises by utilizing green technology to create an innovative building material. This will not only provide a green alternative to current siding materials, but conserve scarce resources, and utilize copious amounts of materials that would normally go wasted.

Progress Summary:

From the progress made in previous years, Husk-to-Home has been able to switch the focus from creating a particle board to expanding the capabilities of the board. This includes improving the recyclability of the boards, expanding the size of the boards, and testing the board’s resistance to UV radiation. Due to unexpected laboratory renovations, as well as the amount of material needed to perform each test and experiment, the team’s progress has slowed. Additionally, with the sudden COVID-19 outbreak and subsequent quarantine, on-campus research has been halted completely. Due to the unavailability of campus facilities, the team has found it difficult to gather reportable results. However, Husk-to-Home has not slowed the research process and continues to prepare for upcoming tests and experiments to resume once campus and laboratory access is again available.

In terms of the recyclability of the Husk-to-Home particleboard, the results from last year’s investigation showed that a board mixture made 100% from a recycled board was roughly 75% as strong as the original board when comparing flexural load test results between an original board centerpiece and a recycled board centerpiece (Table 1). With these promising results, the team investigated ways to facilitate the making of various mixture ratios of recycled board to original board to potentially produce a board with the same quality of strength as the original board. This process includes the physical processing of boards into a fine powder of 100-micron particle size. Due to the strength of the Husk-to-Home boards, the use of a bandsaw to saw the board into slivers for refining in a hammer mill grinder was inefficient and time consuming. The team explored other methods to process a higher quantity of boards at a time for testing of recycled mixtures.

Sample Flexural Test Max Load (Ibf) Max Compressive Stress (MPa)
Original (Center Piece) 100.02 16.1
Original (Edge Piece) 85.87 16.6
Recycled (Center Piece) 75.15 10.63
Recycled (Edge Piece) 54.31 12.61

Table 1: Recycled vs. Original Board Strenght Test Results

The first method explored was a small-scale rock crusher powered by a 1 HP motor that could fit and be safely operated in the lab space. The rock crusher was only able to split the 3’’ × 1’’ × ⅛’’ board pieces into two smaller pieces due to the jaw configuration (Figure 1), which did not create enough friction with the board. The size of the crushed pieces was not small enough to fit into the hammer mill grinder to be refined into powder. The bandsaw method previously mentioned had to be used in combination with the rock crusher to pulverize the boards. This method proved to be inefficient and impractical for the team’s goal to recycle a large number of boards.

Figure 1: Rock Crusher Jaw Configureation

The second method explored was a wood chipper since it has the capability of shredding branches and twigs. A wood chipper was considered because of its blade configuration which consists of a disc with multiple sharp blades rotating at a high RPM, which results in the board pieces coming into contact with the blades multiple times before exiting. The Husk-to-Home board was cut to dimensions of 3.5’’ × 3.5’’ × ⅛’’ to fit the wood chipper’s 4’’× 1’’ opening. The cut boards were then processed through the chipper 5-7 times over a period of 5 minutes, which resulted in small chips 1-2 cm in size. This method using the wood chipper proved to be the fastest. However, the 1.6 HP hammer mill grinder did not have enough power to break down the 1-2 cm chips into a fine powder.

After researching further, the team discovered that the cost of an industrial grade hammer mill capable of pulverizing the small chips into 100-micron powder is the same cost as having 350-400 boards sent to a professional pulverizing service provider. The team decided that utilizing a professional third party to pulverize the boards was the best option financially.

Besides the recycled board testing being done, the team is also taking steps to expand the capabilities, as well as the marketability, of the material by finding methods to elongate the current 9” × 9” board. The purpose of the board elongation research is to make it possible to create boards of any length and width. Originally, the team researched methods of extrusion, but due to the lack of laboratory space and funding, it was not possible to extrude the board in-house. Alternatively, the team has been developing an elongation method that involves adjusting and expanding the current 9” × 9” board. Currently, the team’s approach is through creating a board with interlocking edges and mending them together, one board at a time. To create this board, a new aluminum mold was designed with SolidWorks (Figure 2) and machined with the new shape which includes the interlocking edges. Once two boards with interlocking edges are manufactured with the heat press, the next step is to mend them together.

Figure 2: Top Portion of New Mold with Interlocking Edges

For a simple preliminary test, the team plans to manufacture a board with the interlocking edges, cut the board in half, connect the interlocking edges, and put the broken board back into the heat press. The team has created a Standard Operating Procedure (SOP) for this test, which will give the team a gauge on the effects of heat alone, for mending the material.

Once the team can test the viability of heat treatment, the next step includes refining the mending method. This includes the use of a hot roller over the section of the board that needs to be mended, using a linear actuator to apply consistent and controllable force to both ends of the board. Utilizing heat, pressure and rolling, the team expects this method to induce cross linkages between previously separated boards, to create one seamless board. The strength of this bond will be tested using an Instron machine to perform both tensile and compressive strength tests.

Although in-house extrusion is not possible, Husk-to-Home still plans to test the extrusion capabilities of the material by having it extruded by an outside source. However, after the material was sent to the extrusion company for review, the team was told that the material exceeded the 3% maximum moisture content. Since then, the team has decided to use packets of silica gel packets to minimize moisture content. Although extrusion will require a large amount of material to be prepared, having two differently made boards to test will present the opportunity to compare the material strength, time required, and overall cost of the two methods.

Plans to conduct in-house UV testing continue from last year to observe possible damaging effects from natural UV rays on the Husk-to-Home board and compare durability with competitor boards. Varnish coating will be applied to the boards to observe any added protection from UV rays compared with the uncoated boards. Board samples to be tested will include an uncoated board, a varnish-coated board, and the recycled board. An uncoated board from a competitor will be used as a control for the experiment. The experiment will run for forty-two 12-hour cycles, totaling to 504 hours. Along with in-house testing, board samples will be outsourced to a certified lab in order to calibrate the results of the in-house Husk-to-Home UV tests.

The team has created a SOP and designed an in-house UV testing apparatus. The general schematic and layout of materials and samples is shown in Figure 3. The SOP follows the ASTM- G154 protocol for simulating outdoor UV effects. The UV source will be a UVA-340 bulbsuggested by the protocol, which closely matches the wavelengths of natural outdoor UV contact to a surface.

Other materials to be used for outdoor simulation include a humidifier, heat source, cooling source, temperature controller, humidity controller, and a testing chamber to contain the system. A 16” × 12” × 15” glass tank will be used for the testing chamber and has been fully covered with black masking tape to prevent any UV exposure to the external environment as shown in Figure 4. To observe the potential degradation effects of the UV rays, compression testing and scanning electron microscopy will be conducted on the final samples.

Figure 3: Side View Schematic UV Testing Apparatus

Figure 4: UV Testing Apparatus

Future Activities:

The team has presented methodologies for both extending the boards as well as upholding the quality through UV testing and recyclability options. Once quarantine provisions are lifted, the team will continue their work with the objectives of manufacturing, UV testing, and expanding the particle board size. This, in turn, will affect the previous goal of having patentability by 2020 and will be extended to a later year. In terms of acquiring rice byproducts, the team plans to seek a partnership with an American agriculture company to obtain the raw materials needed for manufacturing the board. This will allow the board-making process to remain eco-friendly and cost efficient. These steps are a great stride in taking the product to a larger scale for the ultimate goal of contributing to the mitigation of climate change impacts and resource deficit.


[1] Peterson, Chris, et al. (2006). Subterranean Termites - Their Prevention and Control in Buildings. Home and Garden Bulletin, 64.(38).
[2] Mich, J. (2019, December 17). The Purpose Of Using An Aggregate Crushing Machine. SaraRiviera. https://www.sarariviera.com/the-purpose-of-using-an-aggregate-crushing-machine/

Journal Articles:

No journal articles submitted with this report: View all 3 publications for this project

Supplemental Keywords:

rice husk; rice straw; plastics; ecofriendly; recyclable; flexural strength; humidity; termites; water-resistant; composite; building material; green engineering; formaldehyde-free; extrusion; machinability

Progress and Final Reports:

Original Abstract
  • 2017 Progress Report
  • 2018 Progress Report

  • P3 Phase I:

    Rice Husk: A Sustainable Building Material for the Philippines  | Final Report