Pits & Quarries
Vancouver firm hopeful fly ash can be replaced in concrete with a cheaper, greener blend
By Rock to Road Staff/PLAN
By Rock to Road Staff/PLAN
A Vancouver-based company is reporting success in its attempt to displace fly ash in ready mix and pre-cast concrete in favour of a cheaper, and more environmentally friendly, alternative.
Progressive Planet Solutions (PLAN) said it has successfully completed phase one of a two-phase test program for its PozGlass SCM product. Based on the results, the company believes it can use a blend of natural pozzolans and recovered post-consumer glass.
Upon successful completion of phase two tests, the company plans to move to a full-scale commercial roll-out of the PozGlass SCM product in Western Canada and the U.S. Pacific Northwest. The objective is to displace fly ash, a by-product of burning coal for electricity generation, with an environmentally friendly product that also enhances performance in ready mix and pre-cast concrete.
Fly ash is the most widely used supplementary cementitious material (SCM) for concrete, according to the company.
Testing with C&CS Atlantic
On Jan. 25, 2021, PLAN announced that it had engaged C&CS Atlantic to complete testing required to commercially launch PozGlass SCM with phase one testing projected to be completed by the end of April 2021.
Michael Thomas leads C&CS Atlantic. He is a professor in the Department of Civil Engineering at the University of New Brunswick (UNB), a registered professional engineer in the province of New Brunswick and has been working in the field of cement and concrete research since 1983.
Prior to joining UNB in 2002, Thomas was on the faculty at the University of Toronto and prior to 1994, worked as a concrete materials engineer with Ontario Hydro in Canada (1991-93) and as a research fellow with the Building Research Establishment in the UK (1986-1991).
Thomas’s main research interests are concrete durability and the use of industrial by-products including pozzolans and slag. He has authored more than 200 technical papers and reports including the book Supplementary Cementing Materials in Concrete.
Phase one focus
Phase one testing focused on pin-pointing proprietary formulations that would enhance durability, workability, and usability factors when replacing portions of Portland Cement in concrete.
Concrete is routinely produced with between 10 per cent to 50 per cent replacement of Portland Cement with SCMs such as fly ash.
It is the company’s objective to maximize potential environmental benefits with PozGlass SCM by using a blend of PLAN’s natural pozzolans and a maximum amount of recovered post-consumer glass, while still mitigating Alkali-Silica Reactivity (ASR). More than 70 per cent of post-consumer glass currently goes to landfill. PozGlass SCM diverts this glass from landfill while providing a CO2 offset of nearly one tonne for every one tonne of PozGlass SCM.
“The biggest hindrances to using 100 per cent ground glass as an SCM are its lower compressive strength compared to other alternatives and its inability to mitigate alkali-silica reactivity in concrete,” stated Steve Harpur, CEO. “The proprietary formulation for PozGlass SCM combines the highest environmental benefits from using a maximum percentage of recovered post-consumer glass while getting a boost of strength and ASR mitigation from our natural pozzolan.”
Tests completed in Phase One in determining the ideal recipe included:
- ASTM C618/C311 tests to determine water demand and strength-activity index
- CSA A23.2-25A tests to determine strength of mortar cubes produced with lime and pozzolan
- ASTM C1897 R3 bound water tests for determining chemical reactivity of pozzolans
- ASTM C1567 Alkali-Silica Reactivity (ASR) expansion tests
- ASTM C441 ASR (Pyrex) tests, and concrete slump trials.
Using the results from the above tests, PLAN has now finalized the recipe of natural pozzolan and post-consumer glass in its PozGlass SCM product and phase one testing is now complete, ahead of schedule.
Phase two testing
Phase two testing has commenced and focuses on testing concrete durability, including compressive strength, chloride permeability testing (RCP) and sulphate resistance.
RCP testing determines the chemical resistance to chlorides such as de-icing chemicals and salt water. Less permeability also means reinforcing (rebar) is better protected from outside chemical attack, increasing the long-term durability of the reinforcing and thus increasing the life expectancy of the concrete.
A lower RCP number is particularly important for concrete produced in coastal cities’ saltwater environments.
With testing ahead of schedule, PLAN expects to have in hand the accelerated RCP test results by late May. and the full results by end of July 2021.
General Use (GU) Portland Cement and Portland Limestone Cement (GUL) are not resistant to sulphate attack without the addition of appropriate proportions of an SCM. Resistance to sulphate attack is required in many concrete and precast applications–such as pilings, slabs, walls, septic tanks, storm sewers, etc. that are exposed to sulphate-rich soils, groundwaters, manures, sewage, and/or silage. Successful test results would further increase the market potential for PozGlass SCM. The six-month sulphate resistance test was commenced ahead of schedule on April 6, 2021 with results available in early October 2021.
In addition, PLAN has kicked-off extensive compressive strength testing on its PozGlass SCM recipe and results will be gathered over the next two months. Full compressive strength testing information will be available in mid-June 2021.
Information gathered in Phase Two will be used to facilitate early-discussions with concrete producers as PLAN moves to full-scale commercialization of PozGlass SCM. The initial target region is Western Canada and the Pacific Northwest with the speed of the roll-out determining timing of expansion into other areas in North America.
About Progressive Planet
Progressive Planet specializes in supplying solutions for a livable planet by developing low carbon, pozzolan-based, cementing products which replace equivalent amounts of Portland Cement and fly ash in concrete. The production of Portland Cement is the second largest global generator of CO2 emissions.
Progressive Planet operates its flagship Z1 Natural Pozzolan Quarry in Cache Creek, British Columbia and is earning a 100 per cent interest in the Z2 Natural Pozzolan Property near Falkland, B.C. and earning a 100 per cent interest in the Heffley Creek Metals and Natural Pozzolan Property. All three properties are within a one-hour drive of Kamloops, B.C., an industrial hub with rail access to Canadian and U.S. markets.