Resonant Shock

See UFTO Note Jan 15, 1998 for background on this remarkable development–turns ash of any kind, tailings, and dirt, into excellent building materials–cheaply and easily–using shock compaction.

The company, Resonant Shock Compaction, is making excellent progress. Here are two items they’ve just sent me (I’ve made no changes):

1. Large Block Testing Program — invitation to participate.
2. Abstract of their paper at recent DOE FETC 3rd annual Conference on Unburned Carbon on Utility Fly Ash.

Proposed Large Block Testing
RSC Compaction Technology
University of Denver


Public Service Company of Colorado and others are interested in testing the RSC technology beyond tests conducted in 1997 using coal combustion by-product (CCB) mixes to make parts for potential construction applications. This testing will test the RSC technology and its ability to fabricate large block parts.

Test Program Participants:

The following are defined as “test program participants,” Boral Material Technologies, Cat Construction Inc., McDonald Farms Enterprises, Public Service Company of Colorado, RSC LLC, Tri-State Generation & Transmission, UtiliCorp United, University of Denver, VFL Technologies, Wallace Industries; and Nuclear Fuel Industries/Stoller Corp. These parties are willing to fund this test program in which large parts will be fabricated for laboratory and field testing. All program participants will share equally in test data without regard to their monetary contribution toward the test program.

Test Objective:

The test objective is to measure strength and durability of large blocks fabricated from CCB mixes compacted by the RSC technology. These large blocks will be approximately 36″ by 48″ by up to 10″ thick. The test program will compare properties of the large blocks with smaller test blocks fabricated and tested in 1997 and 1998.

It is proposed that the following number of quality blocks be fabricated from the following mixes:

(4 Blocks) Cherokee bottom ash and Cherokee No. 4 silo ash
(1 Block) Cameo combination silo/bottom ash
(1 Block ) FGD material from Craig and bottom ash from Hayden
(1 Block) Bottom ash from Nucla and other materials
(1 Block) Bottom ash from Clark Station and Class C ash from Comanche
(1 Block) Mojave bottom ash and fly ash
(1 Block) Japanese bottom ash and fly ash (NFI/Stoller)


The existing RSC machine at the University of Denver will be used. Four more air cushions and associated pneumatics will be installed to fabricate large blocks. A vacuum lifting device will be installed to safely move the large blocks. The vacuum lifting device will enable the same mold to be used repeatedly with minimum cycle time. A low cost curing chamber will be constructed to accelerate block curing to approximately 24 hours. Cement mixers and batch scales will be rented to prepare mixes and core drilling services will be hired to produce cores for laboratory testing.

A single mold that can fabricate the blocks will be provided and upon completion of the program, the mold will become property of RSC LLC.

Mold Design:

A single mold, designed to produce parts approximately 36″ by 48″ by up to 10″ thick will be designed by RSC LLC. Cost of the mold will be paid by test program participants. The mold will be designed for manual disassembly or ejection removal of parts. Testing will also address handling techniques (pins, bolts, lifting holes, etc.) for these test parts. The use of a vacuum lifting device will enable parts to be removed from the mold upon ejection for separate movement to the curing chamber.

Mix Design:

Each test participant will provide sufficient quantities of CCBs at no cost to the program. All costs of raw materials provided to RSC LLC will be borne by test program participants. Disposal of excess material will be arranged by PSCo. Each participant will work with RSC LLC to determine the appropriate mix design. New materials and/or mix designs will first be tested in the small mold to develop mix design for the large blocks.

Machine Operations:

Machine power settings, vibration, shock, acceleration, and period will be set to achieve large block strength and durability characteristics similar to previously fabricated small test blocks.


Block strength and durability will be determined by measurement of compressive strength, porosity, freeze-thaw cycling, and resonant frequency. These tests will be performed on core samples cut from the blocks. Test criteria are based upon the 1997 and 1998 testing of small test block fabricated from similar mixes. Machine parameters and mix composition will be optimized to achieve strong and durable blocks.

Upon completion of curing the blocks will be transported to the PSCo Arapahoe Plant where the test cores will be cut from the blocks for testing at the University of Denver and at Commercial Testing Laboratories (CTL). Participants will determine block performance by placing the blocks in field test conditions at their respective locations. Upon completion of the test program, sample cores or whole parts may be retained by RSC LLC, the University of Denver and/or program participants.

Additional test capabilities available through the University of Denver Environmental Materials Laboratory include acoustic pulse velocity and absorption, acoustic emission, surface porosity, SEM analysis, thermal properties, and TCLP.

Test Results:

Test data obtained from this program will be available to program participants. It is anticipated that test data will be used by program participants and others to identify potential market applications of the RSC technology for large blocks. If a participant requires test data for a specific mix to be treated with confidentiality, that data will be provided only to that participant. However, it is anticipated that the physical characteristics of the large blocks will be reported generically without regard to specific mix designs.

Material Handling Issues:

Material handling techniques used at the University of Denver will not represent anticipated production techniques. Raw materials will be delivered in drums and mixing performed by manually placing mix components into a cement mixer and manually placing the mix into the mold. Equipment for weighing, measuring and blending raw materials may be rented. A forklift and vacuum hoist will be used to move the block. Because of space limitations at the University, different mix designs will be scheduled to reduce on property storage of raw materials and facilitate movement of completed blocks.


The test program schedule will be mutually determined by test program participants. A draft schedule is attached.

Test Program Costs:

The test program participants have agreed to fund this test program for an amount not to exceed $50,000. A test agreement will be prepared in which each participant will indicate their participation and/or level of funding. Participants will additionally bear all costs associated with providing their mix materials to the program, and transportation of mix material and test blocks. PSCo will assist in the coordination of transportation of finished blocks to Arapahoe Station and in the disposal of excess materials.

Other Parties and Potential Recovering of Test Program Costs:

To reduce the test program costs for all participants and to encourage development of the RSC technology with other entities, if test data from this program attract other partners, then the test program participants will be reimbursed a prorated portion of their costs from future agreements in which the large block testing served as the catalyst. For example, each participant’s share will be calculated as a percent of the total program. If a future agreement is signed between RSC LLC and other entities in which the large block test program results enable the agreement to be executed, then each test program participant will receive a fractional share of the agreement value to reimburse them for their participation, up to the full value only of their actual costs. This repayment will be made within three years of the completion of the test program. If no large block agreement with an entity is executed by that time, the test program costs will be forgiven.

Proposed Estimated Budget $45,000 – $50,000.

Presentation at the DOE FETC 3rd Annual Conference
on Unburned Carbon on Utility Fly ASh.


⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭⎭University of Denver

Robert E. Pressey, Keith Wier, and David Frey, RSC LLC.


The RSC technology is a high-g particle packing and forming process that has been licensed for ten years to commercially manufacture refractories weighing up to 5000 pounds. The Public Service Company of Colorado has funded a program at the University of Denver to develop applications of RSC to forming high-carbon Class F fly ash and bottom ash into value-added blocks and panels to construct sound barriers, retaining walls, pond liners, and tilt-up building panels. The Environmental Materials Laboratory is providing test facilities to study RSC process dynamics and product characteristics.

Typically, high-carbon test specimens formed by the RSC process have a compressive strength of 2000 to 5000 psi. Even specimens made from stoker fired ash containing 30% LOI measured 2500 psi. RSC is a robust technology that is tolerant of a wide range of carbon, calcium oxide, and calcium sulfate.

The RSC machine at the Environmental Materials Laboratory is a commercial sized unit capable of compacting 2000 pound parts. Laboratory test specimens are nominally 10 pounds but a mold to make 500 to 1000 pound panels has been designed. Large ash-based blocks and panels will be made for field testing.

Based upon Resonant Shock Compaction of Public Service Company of Colorado Cherokee Plant Class F fly ash and bottom ash this past year, it appears that the RSC technology can compact high-carbon ash into construction blocks, panels, or aggregate that pass many ASTM concrete and masonry strength and durability standards. These standards include compressive strength of 3000 to 5000 psi, sodium sulfate aggregate durability, face fired masonry water absorption, and freeze-thaw 300 cycle tests. These tests were performed by an ASTM certified commercial laboratory.

Papers at the last three DOE FETC Conferences on Unburned Carbonaceous Material on Utility Fly Ash reported that the highest valued ash utilization (cement admixture) is “at risk” because low NOx combustion technology often increases ash carbon content above the ASTM 618 limit of 6%, and the industry preference for 3% or lower. There is considerable effort underway to modify combustion processes to reduce ash carbon content and other efforts to increase alternative high-volume use options for high-carbon ash such as structural fill, agricultural soil amendments, and mine stabilization. Ash use is also limited by transportation cost to market and seasonal demand by the construction industry. Reduced ash use in concrete results in increased cement consumption and an associated one ton of CO2 for each ton of cement clinker produced.

Current research and development is focused on PSCo Cherokee Class F fly ash containing sodium carbonate flue gas conditioning agents and bottom ash, Valmont Class F fly ash and bottom ash, Comanche Class C fly ash, and Hayden bottom ash mixed with fly ash which has been conditioned with limestone ( flue gas desulfurization conditioned fly ash). Other tests include similar ashes, high carbon stoker ash (30% LOI), and circulating fluid bed ash containing highly reactive residual calcined calcium oxide with calcium sulfate.

The RSC market goal is to provide an alternative high-volume, high-valued product utilization of coal combustion products in partnership with electric utilities, ash brokers, construction companies, and manufacturers of concrete blocks, panels, and bricks. Acceptance of RSC ash-based construction materials is predicated upon successfully demonstrating the strength and durability of these products and obtaining the construction industry certifications from the International Conference of Building Officials, National Evaluation Service (ICBO NES).

Large blocks and panels will be made at the Environmental Materials Laboratory for testing in real applications. A transportable commercial plant will be built. Marketing studies have been performed by MBA students at the University of Denver Daniels School of Business. A preliminary conceptual design including capital and operating costs has been completed. Projected capital and operating costs are quite low.

Several electric utilities, environmental contractors, construction companies, and block manufacturers are participating in evaluation of the RSC technology to convert ash into construction blocks and panels. Waste clay and mine tailings are also being tested independently and in combination with ash. Specific products of interest to these parties are low cost highway sound barriers, retaining walls. pond liners, and tilt-up building walls. Test specimens containing greater than 50% bottom ash can be sawed, screwed, and nailed like wood.
⎭The University of Denver, Environmental Materials Laboratory, RSC LLC, and several electric utilities, are continuing studies to understand the unique properties of the RSC formed ash-based products. High-carbon ash formed into high strength products by the RSC process appear to be stronger than conventionally formed high-carbon ash products. RSC particle packing and high-g compaction of fly ash, bottom ash, and binder only requires about 10% water. This bonding process is being studied.

Acoustic velocity absorption and scanning electron microscopy have been used to measure ash and RSC product characteristics. A scanning optical microscopy densitometer system has been developed to measure product porosity. Acoustic velocity will be measured to correlate with product integrity. Differential scanning calorimetry and wide line proton nuclear magnetic resonance can provide information on ash-cement hydration.

The US Department of Energy has funded similar studies of the RSC technology at the University of Denver, Environmental Materials Laboratory to compact and stabilize radioactive and heavy metal contaminated soils. These studies have been conducted in cooperation with the DOE Rocky Flats Environmental Test Site, the DOE Argonne National Laboratories, and the DOE Mixed Waste Focus Area. Preliminary results have shown that RSC compacted soils have lower toxicity leach rates than other methods.

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