Effects of waste plastics as partial fine-aggregate replacement for reinforced low-carbon concrete pavements

Figures & data

Figure 1. Global cumulative plastic waste generation and disposal (Geyer, Jambeck, and Law 2017).

Table 1. Intrinsic properties of common plastics used today (Designer Data 2015).

Type	Density (g/mm^3)	Water Absorption (%)	Impact Strength (MPa)	Compressive Strength (MPa)	Shear Modulus (MPa)	Tensile Strength (MPa)	Bending Strength (MPa)	Youngs Modulus (MPa)	Friction Coefficient
PET	1.375	0.03	15.25	24–77	1375	55	80	2950	0.52
PP	0.904	0.01	0.685	46.5	400	34	41	1325	0.4
PC	1.21	0.15	8	86	700	70	90	2200	0.445
POM	1.415	0.225	0.865	60.5	915	48.5	80	3150	0.275
ABS	1.05	0.325	1.38	73	875	50.5	65	2558	0.35
PMME	1.185	0.35	0.215	103.5	1700	62	134	2450	0.54

Table 2. Surface energy of common adherents (Jialanella 2010).

Substrate	Surface Energy (mJm^−2)
Aluminium	850
Kapton (R)	50
Nylon 6,6	46
Acrylonitrile butadiene styrene	42–55
Polyethylene	31
Polypropylene	30
Poly (methyl methacrylate)	41

Figure 2. Shape and dimensions of plastic aggregates sourced.

Table 3. Slump classes (BSI 2013).

Slump Class	Slump Value (mm)
S1	10 to 40
S2	50 to 90
S3	100 to 150
S4	160 to 210
S5	≥220

Table 4. Equivalent fines and sand replacements.

Plastic Weight (kg)	Equivalent Fines Replacement (%)	Equivalent Sand Replacement (%)
0.756	5	14.29
1.512	10	28.57
2.268	15	42.86

Figure 3. Slump measurement with forms of slump: a) True; b) Shear (adapted after BSI, 2019a; BSI 2019b and BSI 2019c).

Table 5. 40MPa concrete mix design.

Constituent		Design Volume 1 m^3	Batch Volume 0.024 m^3
		Design Mix (kg/m^3)	Batch 0% (kg/m^3)	Batch 5% (kg/m^3)	Batch 10% (kg/m^3)	Batch 15% (kg/m^3)
Cement		420	10.08	10.08	10.08	10.08
Water		200	4.8	4.8	4.8	4.8
Fines (≤4 mm)	Grit (65%)	409.5	9.828	9.828	9.828	9.828
	Holm (35%)	220.5	5.292	4.536	3.78	3.024
Coarse	4–10 mm	587.5	14.1	14.1	14.1	14.1
	10–20 mm	587.5	14.1	14.1	14.1	14.1
Plastic		0	0	0.756	1.512	2.268
Total		2425	58.2	58.2	58.2	58.2

Figure 4. Satisfactory failures of cube specimens (adapted after BSI, 2019a; BSI 2019b and BS1 2019c).

Figure 5. Modified Test Set Up: Push-Out Test, illustrating the adapted push-out test set up used to determine the steel-concrete bond, based on the RILEM: RC6 pull-out test set up (Rilem, 1973).

Figure 6. Slump Measurement of Batches (Illustrating the slump height in mm recorded for the 0%, 5%, 10% and 15% batches in this investigation.).

Figure 7. Compressive Strength of All Test Specimens (the recorded compressive strength in MPa of all 12 cube test specimens in this investigation.).

Figure 8. Average Compressive Strength of Each Batch - (the average compressive strength in MPa for the 0%, 5%, 10% and 15% batches in this investigation, calculated using the data in Figure 8.).

Figure 9. Magnified Image of Plastic Particle Delamination (x10), showing the magnified picture of the delamination between the plastic aggregate and the concrete after failure.

Figure 10. Maximum Push-Out Force of Test Specimens.

Figure 11. Maximum Bond Strength of Test Specimens.

Figure 12. Steel-Concrete Interface After Failure (10% Replacement), illustrating the interface between the steel reinforcement and the concrete specimen for a 10% push-out sample after failure.

Figure 13. Steel-Concrete Interface After Failure (0% Replacement), illustrating the interface between the steel reinforcement and the concrete specimen for a 0% push-out sample after failure.

Figure 14. Crushing of Plastic Aggregate at Steel-Concrete Interface. Illustrating the interface between the steel reinforcement and the concrete specimen for a 10% push-out sample after failure, where crushing of a plastic aggregate particle can be observed which contributed to a decrease in the push-out force.

Figure 15. Splitting Failure Displayed by All Reinforced Concrete Pavement Test Specimens, showing the splitting failure mode of all 12 test specimens after failure following the push-out testing.

Figure 16. Compression Pavement and Cube Failures for: (a) 0%; (b) 5%; (c) 10%; (d) 15%, illustrating the failure modes of the 3 test specimens for the 0%, 5%, 10% and 15% batches; cracking is observed to be approximately equal for all exposed faces which is considered to be satisfactory.

Table 6. Assessment of Slump Requirement.

Batch	Slump Value	Slump Class	Requirement Met?
0%	75	S2	Yes
5%	62	S2	Yes
10%	50	S2	Yes
15%	30	S3	No

Table 7. Assessment of Compression Requirement.

Batch	Compressive Strength (MPa)	Variation from 40MPa Requirement (%)	Requirement Met?
0%	44.08	+10.2%	Yes
5%	40.46	+1.15%	Yes
10%	39.35	−1.63%	No
15%	37.31	−6.73%	No

Table 8. Assessment of Bond Requirement 1.

% plastic Used	Average Bond Strength (MPa)	% Reduction in Bond Strength	Requirement Met?
0	14.60	0	-
5	13.48	8.35%	Yes
10	12.49	16.91%	No
15	11.07	31.83%	No

Table 9. Assessment of Bond Requirement 2 Based on its Compressive Strength.

Specimen	Equation (3) (MPa)	Equation (4) – Pull-out (MPa)	Equation (5) – Splitting (MPa)	Equation (6) (MPa)	Equation (7) (MPa)	Equation (8) (MPa)	Equation (2) Experimental (MPa)	Proposed Max (MPa)	Requirement Met?
0	8.24	16.08	8.53	10.86	13.75	13.96	14.60	13.96	Yes
5	7.90	15.90	8.35	10.40	13.17	13.38	13.48	13.38	Yes
10	7.79	15.68	8.29	10.26	12.99	13.19	12.49	13.19	No
15	7.59	15.27	8.18	9.99	12.65	12.92	11.07	12.92	No

Table 10. Assessment of Bond Requirement 3 Based on 40MPa Requirement.

Equation (3) (MPa)	Equation (4) – Pull-Out (MPa)	Equation (5) – Splitting (MPa)	Equation (6) (MPa)	Equation (7) (MPa)	Equation (8) (MPa)	Equation (2) Experimental (MPa)	Proposed Max (MPa)	Requirement Met?
7.86	15.81	8.32	10.35	13.10	13.30	0%: 14.60	13.30	Yes
						5%: 13.48	13.30	Yes
						10%: 12.49	13.30	No
						15%: 11.07	13.30	No

Table 11. Summary of All Requirements.

Batch	Slump Requirement Met?	Slump Failure Met?	Compressive Strength Met?	Compressive Failure Met?	Bond Requirement 1 Met?	Bond Requirement 2 Met?	Bond Requirement 3 Met?
0%	Yes	Yes	Yes	Yes	Yes	Yes	Yes
5%	Yes	Yes	Yes	Yes	Yes	Yes	Yes
10%	Yes	Yes	No	Yes	No	No	No
15%	No	Yes	No	Yes	No	No	No

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