**5.1 Basic properties**

After granulating cold-bonding recycling coarse aggregates by using the press ingot method, these recycling aggregates were cured in saturated limewater at the temperature of 23± 2.0 °C according to ASTM C192. They were conducted teste of basic properties include specific gravity in oven-dry (OD) and saturated surface dry (SSD) states, absorption, bulk density (i.e. unit weight) and voids according to relevant ASTM standards after the age of 28 days and these results were shown in Table 9. The result indicates that the specific gravity of


Table 9. Basic properties of cold-bonding recycling coarse aggregates.

The promotion of up-to-date green building materials was often impeded by the lack of relevant standards or specifications cited to verify their characteristics (Chang et al., 2009). To avoid such obstruction affecting the application of cold-bonding recycling coarse aggregates in the future, the characteristics of cold-bonding recycling coarse aggregates were certified in accordance with ASTM C33. The aggregate gradation significantly affects on workability, strength, durability, and economy of concrete (Mehta, 1986; Mindess & Young, 1981; Tsai et al., 2006). Therefore the gradation of cold-bonding recycling coarse aggregate was established by the above-mentioned five various diameter particles according to the mean of upper and lower

After granulating cold-bonding recycling coarse aggregates by using the press ingot method, these recycling aggregates were cured in saturated limewater at the temperature of 23± 2.0 °C according to ASTM C192. They were conducted teste of basic properties include specific gravity in oven-dry (OD) and saturated surface dry (SSD) states, absorption, bulk density (i.e. unit weight) and voids according to relevant ASTM standards after the age of 28 days and these results were shown in Table 9. The result indicates that the specific gravity of

B2-3-50 1.80 2.07 14.9 1,191 33.9 B2-3-100 1.81 2.07 14.2 1,192 34.2 B2-3-200 1.81 2.08 14.9 1,176 35.0 B3-50 1.73 2.02 17.0 1,144 33.9 B3-100 1.73 2.01 16.4 1,153 33.4 B3-200 1.73 2.02 16.7 1,103 36.3 B4-50 1.77 2.05 15.8 1,165 34.2 B4-100 1.79 2.06 15.3 1,175 34.4 B4-200 1.80 2.08 15.5 1,141 36.6 B6-50 1.84 2.13 15.8 1,207 33.9 B6-100 1.83 2.11 15.2 1,215 33.6 B6-200 1.83 2.11 15.2 1,201 34.5 A-50 1.66 2.01 21.3 1,084 34.7 A-100 1.69 2.03 20.2 1,101 34.9 A-200 1.74 2.08 19.3 1,133 34.9 B-50 1.55 1.89 22.1 1,033 33.3 B-100 1.58 1.91 21.2 1,045 33.9 B-200 1.65 1.99 20.0 1,088 34.1 L-50 1.23 1.72 40.0 837 32.0 L-100 1.21 1.72 41.6 827 31.6 L-200 1.20 1.73 44.6 811 32.4 Standards ASTM C127 ASTM C127 ASTM C127 ASTM C29 ASTM C29

Specific gravity

Table 9. Basic properties of cold-bonding recycling coarse aggregates.

Basic properties

(SSD) Absorption (%) Unit weight

(kg/m3)

Voids (%)

**5. Characteristics of cold-bonding recycling coarse aggregates** 

limit from size number 56 and 6 recommended by ASTM C33.

Specific gravity (OD)

**5.1 Basic properties** 

Mix No.

cold-bonding recycling coarse aggregate is lighter than primitive aggregate, and the optimum moisture of recycling resource for granulation directly influences the absorption of recycling aggregate. The more optimum moisture of recycling resource, the higher properties of cement-based composite will be.

Other characteristics of ASTM C33 (e.g. contents of chert, clay lumps and friable particles, materials less than 75 μm, and coal and lignite, abrasion, and soundness, etc.) of recycling coarse aggregate were conducted, too. The test results show that the other characteristics of recycling coarse aggregates satisfy the specification of ASTM C33 except the soundness of L-200 (see Table 10). The reason causing the soundness of L-200 is much higher than the ASTM C33 criterion of 12 % may be attributed to the fact that L-200 contains too calcium components to have adequate sulfate resistance (Mangat & Khatib, 1995). This result also implies that using lime sludge or other recycling resources with abundant calcium components to produce cold-bonding recycling coarse aggregates should choose the mixture proportions with cement amount lower than 200 kg/m3 to ensure their sulfate resistance. Table 11 shows the comparisons of properties of cold-bonding recycling coarse aggregate between before and after improvement of particle shape. The results indicate that the unit weight, voids, and abrasion of cold-bonding recycling coarse aggregate have the significant advancement.


Table 10. ASTM C33 other characteristics of cold-bonding recycling coarse aggregates.

Cold-Bonding Technique – A New Approach to Recycle

**Single particle compressive strength (MPa)**

0

construction residual soil.

**Single particle compressive strength (MPa)**

0

granite sludge.

5

10

15

20

25

5

10

15

20

Innocuous Construction Residual Soil, Sludge, and Sediment as Coarse Aggregates 115

**Cement: 50 kg/m3 Cement:100 kg/m3 Cement: 200 kg/m3**

**Age (days)** 1 10 100 1 10 100 1 10 100

Fig. 11. The single particle compressive strength growth of recycling coarse aggregates with

**Age (days)**

Fig. 12. The single particle compressive strength growth of recycling coarse aggregates with

1 10 100

B-50 B-100 B-200

A-50 A-100 A-200

Granite sludge A Granite sludge B

1 10 100

B2-3 B3 B4 B5


Table 11. ASTM C33 other characteristics of cold-bonding recycling coarse aggregates.

### **5.2 Mechanical properties**

Referring to ASTM C39, the cold-bonding recycling coarse aggregate was conducted single particle compressive strength test at the age of 3, 7, 10, 14, 28, 56, and 91-day, respectively. The result indicates that the higher the cement amount, the higher will be the single particle compressive strength test of cold-bonding recycling coarse aggregate as shown in Fig. 11, Fig. 12, and Fig. 13. And the single particle compressive strength increases with the increase of curing age due to the fact that the contribution of hydration of cement and pozzlanic reaction (Dinajar et al., 2008; Malhotra, 1990).

Fig. 11 shows that the cold-bonding recycling coarse aggregates using of B3 and B4 construction residual soil have worse performances. The reason may be attributed to the fact that the B3 and B4 construction wastes are belong to silt and clay with worse properties, respectively. Especially, the single particle compressive strength of recycling aggregate with B granite sludge is significantly higher than A granite sludge as shown in Fig 12. Due to B granite contains some flocculants which are helpful for cement-based composite (like the mechanism of polymer concrete). The addition of flocculants contributes the densification of capillaries and interface within cement-based composite, which will enhance the bonding strength within the recycling coarse aggregate. The cold-bonding recycling coarse aggregate using of lime sludge has the highest single particle compressive strength. The reason causing the single particle compressive strength of recycling aggregate with lime sludge higher than construction residual soil and granite sludge may be attributed to the fact that lime does not only contain a little hydration but also activate the pozzlanic reaction.

Abrasion (%)

B2-3-50 1,191 33.9 45.7 1,205 32.9 39.7 B2-3-100 1,192 34.2 40.7 1,216 33.3 35.4 B2-3-200 1,176 35.0 35.2 1,219 33.4 28.5 B3-50 1,144 33.9 48.9 1,153 33.3 44.2 B3-100 1,153 33.4 44.3 1,173 33.1 38.7 B3-200 1,103 36.3 39.2 1,182 32.9 31.7 B4-50 1,165 34.2 46.7 1,163 33.3 42.1 B4-100 1,175 34.4 42.8 1,182 32.9 36.6 B4-200 1,141 36.6 38.8 1,205 33.0 31.1 B6-50 1,207 33.9 43.8 1,215 33.4 38.2 B6-100 1,215 33.6 40.2 1,219 33.5 34.7 B6-200 1,201 34.5 34.5 1,230 32.8 27.0

Table 11. ASTM C33 other characteristics of cold-bonding recycling coarse aggregates.

Referring to ASTM C39, the cold-bonding recycling coarse aggregate was conducted single particle compressive strength test at the age of 3, 7, 10, 14, 28, 56, and 91-day, respectively. The result indicates that the higher the cement amount, the higher will be the single particle compressive strength test of cold-bonding recycling coarse aggregate as shown in Fig. 11, Fig. 12, and Fig. 13. And the single particle compressive strength increases with the increase of curing age due to the fact that the contribution of hydration of cement and pozzlanic

Fig. 11 shows that the cold-bonding recycling coarse aggregates using of B3 and B4 construction residual soil have worse performances. The reason may be attributed to the fact that the B3 and B4 construction wastes are belong to silt and clay with worse properties, respectively. Especially, the single particle compressive strength of recycling aggregate with B granite sludge is significantly higher than A granite sludge as shown in Fig 12. Due to B granite contains some flocculants which are helpful for cement-based composite (like the mechanism of polymer concrete). The addition of flocculants contributes the densification of capillaries and interface within cement-based composite, which will enhance the bonding strength within the recycling coarse aggregate. The cold-bonding recycling coarse aggregate using of lime sludge has the highest single particle compressive strength. The reason causing the single particle compressive strength of recycling aggregate with lime sludge higher than construction residual soil and granite sludge may be attributed to the fact that

lime does not only contain a little hydration but also activate the pozzlanic reaction.

shape After improvement of particle shape

Voids (%)

Abrasion (%)

Unit weight (kg/m3)

Before improvement of particle

Voids (%)

Mix No.

Unit weight (kg/m3)

**5.2 Mechanical properties** 

reaction (Dinajar et al., 2008; Malhotra, 1990).

Fig. 11. The single particle compressive strength growth of recycling coarse aggregates with construction residual soil.

Fig. 12. The single particle compressive strength growth of recycling coarse aggregates with granite sludge.

Cold-Bonding Technique – A New Approach to Recycle

recycling coarse aggregates.

improvement of particle shape.

sintering recycling aggregate.

Sun Tech Enterprise Co., Ltd.) in Taiwan.

Michigan, USA.

**7. Acknowledgment** 

**8. References** 

**6. Conclusion** 

Innocuous Construction Residual Soil, Sludge, and Sediment as Coarse Aggregates 117

1. The DMDA is appropriate to design the cement-based composite with recycling resources (i.e. construction residual soil, granite sludge, lime sludge) and glass fibers recycled from printed circuit board (PCB) wastes for producing the cold-bonding

2. The press ingot method was developed and successfully granulated the cold-bonding recycling coarse aggregates and the procedure also was established. The proposed stress of granulation by using press ingot method is 35.0 to 42.0 MPa. The cold-bonding technique is able to be applied to handle recycling resources with moisture and reduce the energy consumption and CO2 emission resulted from the oven-dry process. It is worth mentioning that the optimum moisture of blended recycling resource can be estimated by

4. The recycling aggregate produced by using cold-bonding technique can reduce about 65 % CO2 footprint than using sintering technique and the prime cost of cold-bonding recycling aggregate is 5 to 6 times lower than sintering recycling aggregate. Even if the prime cost of cold-bonding recycling aggregate is lower than the primitive aggregate in Taiwan. The single particle compressive strength at 91-day is 1.5 to 3 times higher than

5. The developed cold-bonding recycling coarse aggregate could increase the reuse and recycling of wastes or recycling resources, reduce the energy consumption and CO2 footprint, and diminish the impact on the environment and future generations. Using of lime sludge and cold-bonding technique to produce recycling coarse aggregates could not only has the above-mentioned benefits, but also these recycling aggregates would be applied to the remediation and reconstruction of CPDC An-Shun site in the future.

The author greatly appreciates the grant from Architecture and Building Research Institute, Ministry of The Interior, R.O.C. The continuous supports and technical assistances of Distinguished Professor Juu-En Chang, Professor Chao-Lung Hwang, Associate Professor Lung-Sheng Li, Dr. Gordon Tung-Chin Kung, Mr. Chien-Chih Chang and The Performance Experiment Center, Building Research Institute, Ministry of The Interior, R.O.C. are gratefully acknowledged. Also, the author would like to thank the financial support from National Cheng Kung University and the local factories (i.e. UG Enterprise Co., Ltd., and

ACI Committee 211.1-91. (1991). *Standard Practice for Selecting Proportions for Normal,* 

*Heavyweight and Mass concrete*. American Concrete Institute, Farmington Hills,

the proportion and optimum moisture of every constituent recycling resource. 3. The gradation of cold-bonding recycling coarse aggregate was controllable and established by the five various diameter particles according to requirements engineering or relevant standards and specifications. The unit weight, voids, and abrasion of cold-bonding recycling aggregate have the significant advancement after

Fig. 13. The single particle compressive strength growth of recycling coarse aggregates with lime sludge.

#### **5.3 Comparisons of various aggregates**

According to an approach to estimate energy consumption, CO2 emission, and prime cost of sintering recycling aggregates (Shiao et al., 2002), the cold-bonding recycling aggregates also was evaluated and compared with primitive and sintering aggregate. Table 6 shows the comparisons of properties, energy consumption, CO2 emission, and prime cost of three various aggregates (primitive, sintering, and cold-bonding recycling aggregates). The results show that the recycling aggregate produced by using cold-bonding technique can reduce about 65 % CO2 footprint than using sintering technique (Shiao et al., 2002). The prime cost of sintering recycling aggregate is 5 to 6 times higher than cold-bonding recycling aggregate. Even if the prime cost of cold-bonding recycling aggregate is lower than the primitive aggregate in Taiwan. The gradation of cold-bonding recycling aggregate is controllable and its single particle compressive strength at 91-day is 1.5 to 3 times higher than sintering recycling aggregate.


Table 12. Comparisons of various type aggregates.
