Development and analysis of high-performance green concrete in the urban infrastructure

Figures & data

Figure 1 (a) Permitted aggregate mines by the CDMG in northeastern Colorado and (b) permitted aggregate mines within 3.2 km (2 miles) of the South Platte River.

Figure 2 Average transport distance of coarse aggregates from downtown Denver since 1974.

Table 1 Average C&D debris generation from structures (US EPA 1998).

Source	Thousand tonnes	Per cent
Residential
Construction	5950	11
Renovation	28,933	55
Demolition	17,868	34
Subtotal	52,751	100
Non-residential
Construction	3873	6
Renovation	25,396	36
Demolition	40,906	58
Subtotal	70,175	100
Residential and non-residential
Construction	9823	8
Renovation	54,329	44
Demolition	58,774	48
Total	122,926	100

Figure 3 Production and beneficial use of fly ash since 1966.

Table 2 Mixture designs and fresh concrete property results.

	Batch size: 0.045 m^3
	Control	F30	C30	F40	C40
Materials
Cement (kg)	15.3	10.7	10.7	9.2	9.2
Fly ash (kg)	0	4.6	4.6	6.1	6.1
Coarse agg. (kg)	0	0	0	0	0
Recycled coarse agg. (kg)	37.6	37.2	37.2	37.2	37.2
Fine agg. (kg)	45.5	46.6	47.3	46.2	47.1
Water (kg)	6.4	5.5	5.5	5.5	5.5
MRWR (AT-60) (ml)	30	60	80	30	100
AEA (D-55) (ml)	3	5.8	3.8	5.8	2.5
w/cm	0.42	0.36	0.36	0.36	0.36
Air (%)	6.2	5.7	7.4	6.2	7.5
Fresh concrete properties
Slump (mm)	25	127	89	32	127
Unit weight (kg/m^3)	2263	2220	2248	2192	2164
Concrete temperature (°C)	23.9	26.1	12.2	23.9	12.8
Ambient temperature (°C)	12.8	15.6	7.2	12.8	7.2
Notes: MRWR, mid-range water reducer; AEA, air-entraining admixture.

Table 3 ASTM C 618 specifications and results for Class C and Class F ashes.

	Results		ASTM C 618
	Class F	Class C	Class F (limits)	Class C (limits)
Chemical tests
Sum of SiO2, Al2O3, Fe2O3 (%)	81.63	57.17	70 min	50 min
Calcium oxide (CaO, %)	10.83	27.67
Sulphur trioxide (SO3, %)	0.43	2.18	5.0 max	5.0 max
Total alkalies (as Na2O, %)	1.45	2.27
Available alkalies (as Na2O, %)	0.42	1.56
Physical tests
Loss on ignition (%)	0.67	0.26	6	6
Amount retained on no. 325 sieve (%)	23.87	11.84	34 max	34 max
Specific gravity	2.37	2.67
Moisture content (%)	0.09	0.05	3	3

Table 4 Life-365 results.

Mixture evaluated	Fly ash (%)	Time to first maintenance (years)
OPC	0	9.8
OPC – CNI	0	16.4
OPC – epoxy coated	0	9.8
HPGC-30	30	31.5
HPGC-40	40	54.9

Figure 4 Compressive strength vs. age for HPGC mixtures.

Figure 5 Sodium sulphate expansion results.

Table 5 Summary of 6-month and 1-year sodium sulphate testing.

Mixture	Expansion, 182 days (%)	Improvement from control, 182 days (%)	Expansion, 370 days (%)	Improvement from control, 370 days (%)
Control	0.073	–	0.372	–
F30	0.005	93	0.033	91
F40	0.016	79	0.052	86
C30	0.078	− 6	0.277	26
C40	0.052	29	0.218	41

Figure 6 Rapid chloride ion penetrability test results.

Figure 7 Freeze–thaw durability factors.

Figure 8 LCA of concrete infrastructure in Denver, Colorado. Arrows represent transport and the dashed line represents the urban environment.

Table 6 Material replacement levels and source locations.

	Replacement (%)		Material source/transport
Scenario ID	Fly ash	Recycled aggregate	Fly ash	Cement
BAU-1	0	0		Lyons, CO
HPGC-1	30	0	Pueblo, CO	Lyons, CO
HPGC-2	40	0	Pueblo, CO	Lyons, CO
HPGC-3	30	0	Underwood, ND	Lyons, CO
HPGC-4	40	0	Underwood, ND	Lyons, CO
HPGC-5	0	50		Lyons, CO
HPGC-6	30	50	Pueblo, CO	Lyons, CO
HPGC-7	40	50	Pueblo, CO	Lyons, CO

Table 7 Cost savings for 1 tonne of HPGC – Denver, Colorado.

Mixture	Cement ($/tonne of concrete)	Fly ash ($/tonne of concrete)	Coarse aggregate ($/tonne of concrete)	Fine aggregate ($/tonne of concrete)	Recycled coarse aggregate ($/tonne of concrete)	Total ($/tonne of concrete)	Change in cost (%)
BAU-1	19.85	0	3.4	2.29	–	25.53	0
HPGC-1	13.89	4.29	3.4	2.29	–	23.86	− 6.5
HPGC-2	11.91	5.72	3.4	2.29	–	23.31	− 8.7
HPGC-3	13.89	4.29	3.4	2.29	–	23.86	− 6.5
HPGC-4	11.91	5.72	3.4	2.29	–	23.31	− 8.7
HPGC-5	19.85	0	0	2.29	3.88	26.02	1.9
HPGC-6	13.89	4.29	0	2.29	3.88	24.35	− 4.6
HPGC-7	11.91	5.72	0	2.29	3.88	23.79	− 6.8