Progress 09/01/03 to 10/31/05
Outputs
Cement-bonded strawboard was developed as a new siding product with improved aesthetic attributes, workability and engineering characteristics. The high extractive and wax contents of straw present important challenges to production of cement-bonded strawboard. A variety of straw pretreatment techniques were evaluated. The combination of straw pretreatment, introduction of admixtures, and production temperature/pressure time-history contributed toward development of cement-bonded strawboards which met the standard requirements for cement-based siding products. A thorough competitive investigation of cement-bonded strawboard was conducted against commercial cement-bonded fiberboard and particleboard products. The results indicated that: (i) cement-bonded strawboard offers commercially viable physical and mechanical attributes which are competitive against available commercial products, and also meet relevant standard requirements; and (ii) Cement-bonded strawboard
offers desirable durability characteristics under accelerated aging effects representing diverse climatic effects on siding products, and compete well with commercially available siding products knows for long-term durability. Scaled-up processing techniques were developed for production of large-scale cement-bonded strawboard panels. These panels were used in a field installation for assessment of the compatibility of cement-bonded strawboard with conventional construction techniques, and for monitoring long-term performance of strawboard under actual climatic effects. The field installation confirmed compatibility of cement-bonded strawboard with common construction practices. The distinctly high toughness of cement-bonded strawboard, when compared with cement-bonded fiberboard and wood particleblard, minimized damage to the product during installation, and would be a major advantage in terms of damage control in service. The cement-bonded strawboard field installation has performed
satisfactorily so far, after few months of exposure to Fall and Winter weathering effects in mid-Michigan. A competitive commercial analysis of cement-bonded strawboard was conducted, based on which market entry strategies were devised for introduction of the products to siding markets. The competitive advantages of cement-bonded strawboard as well as the obstacles against market introduction of the technology were identified. Potential commercialization partners with complementary resources and capabilities for market introduction of the technology were identified and contacted in order to develop further insight into the targeted marketplace and develop a viable commercialization plan. The market needs and constraints were thoroughly assessed through these commercial contacts, and the technical and business tasks to be implemented toward market introduction of the technology were identified. While the growth in siding applications of cement-bonded fiberboard is indicative of
positive market prospects for cement-based siding products, the excess production capacity currently available for cement-bonded fiberboard represents a key obstacle against market introduction of cement-bonded strawboard.
Impacts
A 10% (110 million meter squared per year) share of U.S. siding markets for cement-bonded strawboard would make value-added use of about 1 million tons/yr of cereal straw; the resulting direct benefits to rural economies (value-added markets for straw, new employment opportunities in production plants) are estimated at about $100 million/yr, with additional indirect financial benefits of about $300 million/yr. Close to 15 strawboard production plants would be needed to serve this market share. These plants, due to the economy of residue transportation, would be located in rural areas, where close to 5,000 new employment opportunities would be created.
Publications
- No publications reported this period
|
Progress 10/01/03 to 09/30/04
Outputs
The effects of introduction of straw after different pre-treatments on compressive strength of Portland cement mortar mixtures were evaluated experimentally in order to assess the inhibitory effects of straw on hydration of cement and determine the effectiveness of various treatments on enhancement of this compatibility. The following conclusions were derived based on experimental results. 1. Untreated straw has strong inhibitory effects on hydration of cement; the extent of such inhibitory effects depends on straw type. 2. Immersion in lime-saturated water for 2-3 hours is particularly effective in removal of inhibitory compounds from straw, thereby improving the compatibility of straw with hydration of cement. 3. Different straw types respond differently to different treatment conditions; relative standings of different straw types based on their inhibitory effects would be different prior to and after immersion in hot, lime-saturated water. 4. Proper selection and
treatment of straw can open the prospects for value-added use of an abundantly available agricultural by-product as lightweight reinforcement (in lieu of wood particles) in thin-sheet cement products (cement-bonded particleboards), masonry units, and other cement-based products. In order to establish a competitive basis for evaluation of the performance attributes of cement-bonded strawboard, a comprehensive experimental investigation was conducted on commercial thin-sheet cement products. The resulting database provides a control basis which guides our efforts to develop commercially viable cement-bonded strawboard building products. Comprehensive experimental investigations were conducted towards establishment of optimum formulations and curing conditions for processing of pretreated straws into commercially viable cement-bonded strawboards. This effort yielded the following key conclusions regarding optimum formulation of cement-bonded strawboard. 1. The ratio of straw to
cement-based binder should be limited to about 0.20. 2. The ratio of water to cement-based binder should not exceed about 0.33. 3. Cement-bonded strawboard greatly benefits from the introduction of silica fume (a fine pozzolan) as replacement for about 10% (by weight) of cement. 4. Cement-bonded strawboard should be produced with bulk specific gravities exceeding about 1.45 to meet modern (ASTM C 1185 and ASTM C 1225) strength requirements for thin-sheet cement building products. 5. Type IA cement offers a greater promise than Type I cement for use in cement-bonded strawboard, with the uniform entrainment of fine air voids by Type IA cement contributing to enhanced compaction of strawboard at reduced bulk density. 6. The combination of silica fume with sodium silicate, sodium bicarbonate and water-repelling admixtures at selected dosages provide cement-bonded strawboard with a desirable balance of mechanical and durability characteristics which promise to meet the modern (ASTM C 1185
and ASTM C 1225) requirements for thin-sheet cement building products.
Impacts
Among the siding products for building construction, vinyl siding is expected to retain its dominant position through 2010, with wood fiber cement siding products nearly doubling their market share. The current wood fiber cement production capacity in North America is not sufficient to meet the 2010 projected demands. This presents a market opportunity for cement-bonded strawboard which matches the technical advantages of wood fiber cement at reduced cost and with improved workability and aesthetics. Replacement of wood with abundant agricultural residues enhances the economic and environmental position of cement-bonded strawboard versus wood fiber cement. Commercial production of cement-bonded strawboard would contribute to rural economies by providing value-added outlets for major residues of farming activities, and also by expanding the manufacturing basis and generating new employment opportunities in rural areas.
Publications
- No publications reported this period
|
|