**2.1 Cementitious materials**

The type I Portland cement produced by Universal Cement Corporation, BF slag provided by CHC Resources Corporation, and class F fly ash supplied by Taiwan Power Station are employed to produce the cold-bonding recycling coarse aggregates. These cementitious materials conform to the related American Society for Testing and Material (ASTM) standards and their physical properties as well as chemical compositions are shown in Tables 3.


Table 3. Physical properties and chemical compositions of cementitious materials.

### **2.2 Recycling resources**

There were four various construction residual soils (i.e. B2-3, B3, B4, and B6 categories) employed to make the cold-bonding recycling coaese aggregates as shown in Fig. 2.

1989) that is the higher packing density of component materials of concrete, the higher will be the properties of concrete. To ensure characteristics of cold-bonding recycling coarse aggregates are acceptable, the cement-based composites were granulated as the recycling coarse aggregates with a higher stress of greater than 28 MPa after proportioning and mixing. These mixture proportions and conditions of granulation will

The constituent materials of cold-bonding recycling coarse aggregates mainly include 1) cementitious materials: cement, BF slag, and fly ash, 2) recycling resources: the innocuous construction residual soil, granite sludge, and lime sludge, 3) other materials: the recycling

The type I Portland cement produced by Universal Cement Corporation, BF slag provided by CHC Resources Corporation, and class F fly ash supplied by Taiwan Power Station are employed to produce the cold-bonding recycling coarse aggregates. These cementitious materials conform to the related American Society for Testing and Material (ASTM) standards and their physical properties as well as chemical compositions are shown in

Table 3. Physical properties and chemical compositions of cementitious materials.

employed to make the cold-bonding recycling coaese aggregates as shown in Fig. 2.

There were four various construction residual soils (i.e. B2-3, B3, B4, and B6 categories)

Item Cement BF slag Fly ash

SiO2 22.16 35.56 49.86 Al2O3 5.63 14.34 37.89 Fe2O3 2.17 0.33 3.18 CaO 67.35 50.23 6.04 MgO - 5.66 - SO3 2.08 0.95 0.66 f-CaO 0.08 - - TiO2 0.25 0.44 1.20 Na2O 0.31 - - K2O 0.15 0.09 0.44 Loss on ignition 0.51 0.31 6.08

Specific gravity 3.15 2.90 2.14 Surface area (m2/g) 2,970 4,350 3,110 Time of initial setting (min) 135 - - Time of final setting (min) 377 - -

be illustrated in subsequent sections.

**2. Constituent materials** 

glass fibers and superplasticizer.

**2.1 Cementitious materials** 

Tables 3.

Physical properties

Chemical compositions (%)

**2.2 Recycling resources** 

(d) B3 in original state (e) B3 in oven-dry state (f) B3 with moisture of 14.0 %

(g) B4 in original state (h) B4 in oven-dry state (i) B4 with moisture of 14.0 %

(j) B6 in original state (k) B6 in oven-dry state (l) B6 with moisture of 14.0 %

Fig. 2. Photos of four construction residual soils in various moisture states.

In which B2-3, B3, and B4 categories were provided from a local collecting plant of construction wastes in Tainan as well as the construction residual soil of B6 category was acquired from a construction site near Shida Road in Taipei, Taiwan. For engineering purposes, these construction residual soils of B2-3, B3, B4, and B6 categories were classified as SP (i.e. poorly graded sand), ML (i.e. silt), SM (i.e. silty sand), and CL (i.e. lean clay), respectively according to Unified Soil Classification System (ASTM, 2006). Their specific gravity as well as chemical compositions are shown in Tables 4.

Cold-Bonding Technique – A New Approach to Recycle

Fig. 4. Photos of lime sludge in various moisture states.

Criteria of general enterprise

Criteria of green building

**2.3 Other materials** 

Table 5. TCLP results of recycling resources.

glass fibers also should be regarded as a recycling resource.

Innocuous Construction Residual Soil, Sludge, and Sediment as Coarse Aggregates 101

(a) A in original state (b) A in oven-dry state (c) A with moisture of 45.0 %

Cd (mg/L)

A granite sludge 0.087 0.180 0.049 0.005 0.003 N.D. B granite sludge 1.270 0.080 0.032 0.006 0.009 N.D. Lime sludge 0.313 0.001 0.026 0.007 0.079 N.D.

wastes 5.0 1.0 5.0 15.0 5.0 0.2

material 1.5 0.3 0.3 0.15 0.3 0.005

Type G superplasticizer, a carboxylate-based, was purchased from local factory in Taiwan and the characteristics of superplasticizer as shown in Table 6. The glass fibers were recycled from printed circuit board (PCB) wastes by Much Fortune Technology Co., Ltd. In fact, the

B2-3 construction residual soil <0.02 <0.02 <0.02 <0.02 0.0018 N.D. B3 construction residual soil <0.02 <0.02 <0.02 <0.02 N.D. N.D. B4 construction residual soil <0.02 <0.02 <0.02 <0.02 N.D. N.D. B6 construction residual soil <0.02 <0.02 <0.02 <0.02 0.0015 N.D.

Pb (mg/L)

Cu (mg/L)

As (mg/L)

Hg (mg/L)

In Taiwan, the government continuously makes great efforts to promote the development of recycling materials (like green building materials, etc.) produced with the recycling wastes or resources over the past decade. For protecting the safety and health of users and purchasers, the stringent control standards were establish to prevent any noxious components from incorporating into the recycling resources. In other words, any recycling wastes or resources must confirm to the stringent control standards before they were used to manufacture any recycling products. The toxicity characteristic leaching procedure (TCLP) test acts an impotant and decisive role in the above-mentioned control standards. The TCLP results of recycling resources were below the criteria of general enterprise wastes

and green building materials (Chiang, 2007) in Taiwan as shown in Table 5.

Cr (mg/L)


Table 4. The specific gravity and chemical compositions of recycling resources.

In order to accelerate the settling of sludge for facilitating the recycling of water, the flocculants were added into the water reclamation pond in masonry plants. Therefore there were two various granite sludges (see Fig. 3), A granite sludge does not contain any flocculants and B granite sludge contains a few flocculants, were provided from the Stone and Resource Industry R&D Center in Hualien, Taiwan and their compositions were shown in Table 4.

Fig. 3. Photos of granite sludge in various moisture states.

The lime sludge (see Fig. 4) was provided from the CPDC An-Shun site that was a decommissioned chloroalkaline and pentachlorophenol manufacturing plant in Tainan, Taiwan (Chao et al., 2008). The specific gravity and chemical compositions of lime sludge are shown in Tables 4.

CaO (%) 1.96 2.29 2.16 0.27 12.08 6.39 55.76 SiO2 (%) 75.70 73.20 69.46 69.52 55.49 70.63 21.70 Al2O3 (%) 14.83 16.77 18.68 21.29 11.04 14.76 8.45 Fe2O3 (%) 3.01 3.71 4.17 4.08 10.90 2.72 2.57 MgO (%) N.D. N.D. 0.85 0.70 8.08 N.D. 6.07 SO3 (%) 0.08 0.14 0.23 0.02 0.09 0.07 3.81 K2O (%) 2.65 2.92 3.43 3.17 1.56 4.69 N.D. TiO2 (%) 0.54 0.67 0.72 0.70 0.22 0.29 0.39 V2O5 (%) N.D. N.D. N.D. N.D. N.D. N.D. N.D. Specific gravity 2.57 2.64 2.54 2.870 2.90 2.70 2.62

Table 4. The specific gravity and chemical compositions of recycling resources.

In order to accelerate the settling of sludge for facilitating the recycling of water, the flocculants were added into the water reclamation pond in masonry plants. Therefore there were two various granite sludges (see Fig. 3), A granite sludge does not contain any flocculants and B granite sludge contains a few flocculants, were provided from the Stone and Resource Industry R&D Center in Hualien, Taiwan and their compositions were shown in Table 4.

(a) A in original state (b) A in oven-dry state (c) A with moisture of 19.5 %

(d) B in original state (e) B in oven-dry state (f) B with moisture of 20.0 %

The lime sludge (see Fig. 4) was provided from the CPDC An-Shun site that was a decommissioned chloroalkaline and pentachlorophenol manufacturing plant in Tainan, Taiwan (Chao et al., 2008). The specific gravity and chemical compositions of lime sludge

Fig. 3. Photos of granite sludge in various moisture states.

are shown in Tables 4.

Construction residual soil Granite sludge Lime sludge B2-3 B3 B4 B6 A B

(a) A in original state (b) A in oven-dry state (c) A with moisture of 45.0 %

Fig. 4. Photos of lime sludge in various moisture states.

In Taiwan, the government continuously makes great efforts to promote the development of recycling materials (like green building materials, etc.) produced with the recycling wastes or resources over the past decade. For protecting the safety and health of users and purchasers, the stringent control standards were establish to prevent any noxious components from incorporating into the recycling resources. In other words, any recycling wastes or resources must confirm to the stringent control standards before they were used to manufacture any recycling products. The toxicity characteristic leaching procedure (TCLP) test acts an impotant and decisive role in the above-mentioned control standards. The TCLP results of recycling resources were below the criteria of general enterprise wastes and green building materials (Chiang, 2007) in Taiwan as shown in Table 5.


Table 5. TCLP results of recycling resources.

#### **2.3 Other materials**

Type G superplasticizer, a carboxylate-based, was purchased from local factory in Taiwan and the characteristics of superplasticizer as shown in Table 6. The glass fibers were recycled from printed circuit board (PCB) wastes by Much Fortune Technology Co., Ltd. In fact, the glass fibers also should be regarded as a recycling resource.

Cold-Bonding Technique – A New Approach to Recycle

the future.

employing the DMDA procedure.

resources, BF slag, and fly ash in filler system.

Innocuous Construction Residual Soil, Sludge, and Sediment as Coarse Aggregates 103

destroyed due to disintegration and crack formation. To avoid these problems cement-based composite mixture designed with low water amount and low cement content is proposed.

Durability design should be considered for improving both the fresh and hardened stages of the cement-based composite and should finally extend their service life. First and foremost the cement-based composite mixture design should have a very low water amount (Neville, 2000) so as to minimize the shrinkage rate or the expansion rate (Hwang & Lu, 2000). Then, the cement-based composite must be designed to satisfy the construction needs such as with zero or low slump for cold-bonding recycling aggregate or roller compacted concrete, with high slump for self- consolidating concrete or high performance concrete, type of construction work, and the required final finished result. In plastic stage, the cement-based composite is designed to prevent the occurrence of plastic shrinkage cracks due to excess water evaporation from its surface. A certain amount of fibers should be included in the cement-based composite to absorb energy and in the case of crack formation, to stop their propagating (Rossi et al., 1987). The addition of pozzolanic materials (i.e. BF slag and fly ash) is necessary to help the self-healing of cracks if they are generated (Tsai et al., 2009). A strict standard operation procedure for mixture proportion, material selection, trial batch,

quality control and curing are required to lower the possibility of crack formation.

**3.3 Mixture design procedure of cold-bonding recycling aggregate by DMDA** 

(1) Select proper material resource and gather material information.

The following steps can be used to provide computational basis for designing the cementbased composite mixture to produce the cold-bonding recycling coarse aggregates

This is an important step for the mix design of cement-based composite mixture for producing the cold-bonding recycling coarse aggregates. The basic quality information of the ingredients of cement-based composite is necessary for the purpose of quality control. (2) Obtain the maximum dry loose density (i.e. unit weight) by iteratively packing recycling

The DMDA was adopted to design the intended cement-based composites for producing the cold-bonding recycling coarse aggregates. In order to minimize the shrinkage rate or the expansion rate and ensure the durability of cold-bonding recycling coarse aggregate, a very low water-to-cementitious ratio of 0.20 was selected to design mixture proportions of cement-based composite. And a total of 39.4 kg glass fibers (the volume=0.02 m) was added to reach the intended design value of 2.0 % by volume of the cement-based composite for preventing such cracks and enhancing the toughness as well as volume stability (Rossi et al., 1987; Tsai et al., 2009, 2010) of cold-bonding recycling coarse aggregate. In view of cement has the most energy consumption and CO2 emission in all constituent materials of cold-bonding recycling coarse aggregate as well as the abovementioned disadvantages, the amount of cement is limited to less than 200 kg/m3. There were three various amount of cement (i.e. 50, 100 and 200 kg/m3) designed for every recycling resource to magnify the application cold-bonding recycling coarse aggregates in


Table 6. The characteristics of carboxylate-based superplasticizer.
