Carbon Upcycling to Improve Ready-Mixed Concrete

Transcription

1 Fifth International Conference on Accelerated Carbonation for Environmental and Material Engineering (ACEME 2015) June 24, 2015 Carbon Upcycling to Improve Ready-Mixed Concrete Sean Monkman 1,Mark MacDonald 1, Paul Sandberg 1, Doug Hooton 2 1 CarbonCure Technologies 2 University of Toronto, Department of Civil Engineering Simply Better Concrete 1

2 CONCRETE is the most abundant man-made material on the planet and makes up about 50% by mass of all materials produced globally. Materials and the Environment, 2nd Ed, by M.F. Ashby, 2012 Simply Better Concrete 2

3 CEMENT is the most important component of concrete and is in ever increasing demand 6 5 Gt Cement Other developing countries India China USGS/IEA OECD, industrial nations Year Simply Better Concrete 3

4 A SOBERING LOOK AT DEMAND 7 6 Cement consumption (Gt) China used 47% more cement between 2011 and 2013 than the United States used in the entire 20 th century. Making the Modern World: Materials and Dematerialization, Vaclav Smil 0 USA ( ) China ( ) Simply Better Concrete 4

5 CO 2 EMISSIONS are a byproduct of cement production and total about 5% of the total annual global. One tonne of cement clinker results in about 865 kg of CO 2 emitted. Damtoft et al, (2008). Cement and Concrete Research, 38(2), Simply Better Concrete 5

6 Carbon solution: upcycle CO 2 CO 2 CO 2 permanently mineralized within concrete CaCO 3 Limestone CaO Cement CaCO 3 bound within Concrete Add aggregates & water Simply Better Concrete 6

7 Carbon dioxide can react with cement Cement + water + CO 2 calcium carbonate 3CaO SiO 2 + 3H 2 O 3Ca 2+ + SiO OH - 2CaO SiO 2 + 2H 2 O 2Ca 2+ + SiO OH - Ca(OH) 2 + H 2 O Ca OH - + H 2 O CO 2 (g) CO 2 (aq) CO 2 (aq) + H 2 O H 2 CO 3 (aq) H 2 CO 3 (aq) HCO - 3 (aq) + H + HCO - 3 (aq) CO -2 3 (aq) + H + Dissolution (Ca 2+ Supply) + CO 2 Dissociation (CO 3-2 Supply) = Ca +2 (aq) + CO 3-2 (aq) CaCO 3 (s) Precipitation (CO 2 Storage) Simply Better Concrete 7

8 Gas system meters CO2 Simply Better Concrete 8

9 Inject CO 2 into the concrete as it mixes Simply Better Concrete 9

10 Trial summary Truck 1 Three sequential doses of CO 2 after batching Truck 2 One dose of CO 2 during batching o Workability, temperature, isothermal calorimetry o Compressive strength (1, 3, 7, 28, 56, 91 days), o Resistivity Simply Better Concrete 10 10

11 Trial outline Sample Code Condition CO 2 dose (%bwc) Age at injection (min) Slump (inches) Mix Temperature ( C) 801 Control CO CO CO CO Workability was decreasing Temperature was increasing attributable to the hydration time or CO 2 addition? Simply Better Concrete 11 11

12 Calorimetry Power Normalized Power (a.u.) Control 801 CO2 802 CO2 803 CO2 804 CO Time After Mixing (hours) Simply Better Concrete 12 12

13 Serial dose Early strength Compressive Strength (MPa) % 107% 106% 106% 112% 111% 1 day 108% 3 day 109% 7 day 115% Compresive Strength (psi) Control CO2-1 CO2-2 CO2-3 Batch Simply Better Concrete 13 13

14 Serial dose Late strength Compressive Strength (MPa) % 85% 103% 110% 116% 106% 28 day 107% 56 day 111% 91 day 107% Compresive Strength (psi) Control CO2-1 CO2-2 CO2-3 Batch Simply Better Concrete 14 14

15 Strength - CO 2 during batching Compressive Strength (MPa) % 126% 121% 115% 118% Compressive Strength (psi) 0 1 day 3 day 7 day 28 day 56 day Test Age 0 Simply Better Concrete 15 15

16 Strength benefit conclusions Age (days) 0801 Control % CO % CO % CO % CO % 100% 100% 100% 100% 100% 99% 107% 106% 104% 85% 103% 106% 112% 111% 110% 116% 106% 108% 109% 115% 107% 111% 107% 114% 126% 121% 115% 118% 115% Best results observed when CO 2 added during batching Resistivity results assured no change to chloride risk Simply Better Concrete 16 16

17 Mechanism In-situ formation of nano-caco3 consistent with ex-situ nano-calcite addition Simply Better Concrete 17

18 Environmental Impact Doses are small, but industry is huge A consistent strength benefit allows for increased SCM usage thereby lowering the carbon footprint of the concrete mix design. Simply Better Concrete 18 18

19 Further work - Durability Study Strength Compressive and flexural Exposure Freeze-thaw durability, salt scaling Chloride Permeability RCPT, bulk diffusion test Shrinkage Service life carbonation testing Abrasion testing Simply Better Concrete 19 19

20 Thank You Sean Monkman VP Technology Simply Better Concrete 20 20