Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in water

Article abstract of DOI:10.3762/bjoc.5.68

The Knoevenagel condensation between aromatic aldehydes and malononitrile, ethyl cyanoacetate or malonic acid with hydroxyapatite supported caesium carbonate in water is described. HAP-Cs₂CO₃ was found to be a highly active, stable and recyclable catalyst under the reaction conditions.

Full text of DOI:10.3762/bjoc.5.68

Accepted Manuscript
Study on Feasibility of Reutilizing Textile Effluent Sludge for Producing Concrete
Blocks
Bao Jian Zhan, Chi Sun Poon
PII:
S0959-6526(15)00323-6
10.1016/j.jclepro.2015.03.083
JCLP 5351
DOI:
Reference:
To appear in: Journal of Cleaner Production
Received Date: 13 October 2014
Revised Date: 5 March 2015
Accepted Date: 28 March 2015
Please cite this article as: Zhan BJ, Poon CS, Study on Feasibility of Reutilizing Textile Effluent
Sludge for Producing Concrete Blocks, Journal of Cleaner Production (2015), doi: 10.1016/
j.jclepro.2015.03.083.
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Study on Feasibility of Reutilizing Textile Effluent Sludge for
Producing Concrete Blocks
Bao Jian Zhan, Chi Sun Poon*
Department of Civil and Environmental Engineering,
The Hong Kong Polytechnic University
Hung Hom, Kowloon, Hong Kong
*E-mail: cecspoon@polyu.edu.hk
Tel: +852 2766 6024
Fax: +852 2334 6389
Abstract:
With an increasing interest in recycling and reusing waste, there is a need to carry out
research on exploring ways to transform industrial wastes into construction materials.
This paper attempts to explore the feasibility of reutilizing textile effluent sludge (TES)
for producing concrete blocks with a pretreatment step. The lime-based pretreatment
process was adopted to remove ammonia in TES which had been found to lead to bad
odor and strength loss of the concrete blocks. The concrete blocks were prepared with an
aggregate to cement ratio of 12, 10 and 6. The pretreated TES was adopted to replace the
fine aggregate at a mass ratio ranging from 0% to 30%. The compressive strength and
drying shrinkage values were determined to evaluate the performance of concrete blocks
containing TES. The results indicated that the lime-based pretreatment process can lower
the ammonia concentration in TES significantly. The concrete blocks with a lower TES
content and lower ammonia concentration had higher compressive strength and better
volume stability. When the TES content in the concrete blocks was about 10%, the
concrete blocks with an aggregate to cement ratio of 10 can satisfy the minimum strength
requirement for non-load bearing applications. Meanwhile, the result of leaching test
indicated that the toxic trace metals present in textile effluent sludge could be
stabilized/solidified and metal leaching from the concrete blocks is not a concern.

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Keywords:
Textile effluent sludge, lime-based pretreatment, concrete block, ammonia, leaching
1. Introduction
Textile industry involves processing or converting raw material/fabric into finished
clothing materials via several processes which consume large amount of water and
produces polluting waste effluents (Karthikeyan and Mohan, 1999) containing non-
biodegradable and toxic dissolved substances (Khatri et al., 2015). Previous studies
confirmed that the levels of pollutants in textile effluent were considerably higher than
the discharge limits stipulated by local regulations (Noorjahan, 2011, Paul et al., 2012).
Therefore, treatment of the textile effluent before discharge is almost mandatory leading
to the production of huge volumes of textile effluent sludge. Besides landfill disposal of
the sludge, there are growing interests in trying to re-utilize the sludge.
Currently, cement based binders are extensively adopted for treating industrial solid
waste containing radioactive or hazardous substances to prevent the leaching of
contaminants to the environment (Batchelor, 2006). Stabilization of hydrocarbons in
petroleum solid waste was also investigated with cement-based S/S process (Karamalidis
and Voudrias, 2007,). It was found that inclusion of cement blended with pozzolanic
materials increased the leachability of most polycyclic aromatic hydrocarbons in
solidified sludge samples. Sewage sludge from have been studied for fired bricks
production, but high content of this sludge resulted in a degradation of mechanical
strength and absorption of fired bricks (Ingunza et al., 2011).
Several kinds of waste are also reused in combination with cement for producing
concrete products, including waste marble (Gencel et al., 2012), ferrochromium slag
(Gencel et al., 2013) and CRT funnel glass (Ling and Poon, 2014). Recently, reutilization
of sewage sludge ash (SSA) was reported to manufacture blocks with best performance
by replacing 10% sand with SSA (Francisco et al., 2014). Even another study assessed
the potential feasibility of reusing lime-dried sludge as a replacement of limestone
material for clinker production (Xu et al., 2015). Rala et al. (2015) have explored the

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feasibility of reuse the marble slurry to partially replace cement for concrete production.
They found that 10% of cement replaced by marble slurry was the optimum content to
produce concrete with the requisite strength and enhanced durability.
As early as 1980s, sludge from wastewater treatment plants had been studied and reused
for producing fired clay bricks, and the results indicated that the compressive strength
was acceptable while the texture and finish on the surface of bricks were rather poor (Tay,
1987). The reuse potential of textile effluent sludge for the production of cement-sludge
bricks was also confirmed in previous study (Hema and Suneel, 2009), and the
compressive strength of the product could even meet the requirement of structural
application as described in the India standard. However, the density and compressive
strength of the cement brick decreased with increasing amounts of sludge in the brick.
The negative effects of textile effluent sludge on properties of concrete block were also
demonstrated in some other studies. Herek et al. (2012) suggested that incorporating no
more than 20% by mass of sludge could lead to good quality concrete bricks in terms of
mechanical characteristics; leaching and solubilization tests proved the sludge brick were
inert. Balasubramanian et al. (2006) also reported an investigation on replacing 10%, 20%
and 30% of cement with textile effluent sludge to produce flooring tiles, pavement blocks,
hollow blocks, solid blocks and burnt clay bricks. It was concluded that a maximum of 30%
substitution for cement with textile effluent sludge may be possible in fabrication of non-
load bearing building materials.
Few studies gave a valid explanation for the adverse effects of textile effluent sludge on
properties of cement-sludge mixtures. It was speculated that the presence of chloride and
sulfates in sludge resulted in decline in strength (Raghunathan et al., 2010); Pandey et al.
(2011) inferred that Zn and Pb salts in the sludge caused precipitation of protective
coatings around cement grains during cement hydration, leading to a decrease in
compressive strength.
In this paper, an investigation of assessing the feasibility of reutilizing a textile effluent
sludge (TES) with high concentrations of ammonia is reported. Pretreating processes for
the TES were attempted in order to alleviate the deleterious effects of TES on the
properties of cement-sludge mixtures. Then, the pretreated sludge was used as a partial

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replacement of fine aggregate to produce concrete blocks. The evaluation of the concrete
blocks was conducted in terms of compressive strength and drying shrinkage.
2. Materials and experimental program
2.1 Characteristics of textile effluent sludge
The textile effluent sludge (TES) was obtained from a bleaching and dyeing factory
which is located in Guangdong Province of Chinese mainland. The sludge collected (as
shown in Figure 1) was generated from the wastewater treatment process of the factory.
A series of physical and chemical tests were conducted to characterize the sludge. The
analysis results of the TES are shown in Table 1.
2.2 Pretreatment methods
Considering the high concentration of ammonia (NH4-N) in the sludge, it was necessary
to remove the ammonia salts in TES for two main reasons. First, ammonia is a strong
odours compound which would be unacceptable to the workers handling the TES, and the
ultimate users of TES related products. Moreover, a previous study on reusing ammonia
contaminated fly ash in cement mortar and concrete demonstrated that the presence of
ammonia can inhibit cement hydration and thus lower the compressive strength (Kim et
al., 2007). In this study, anhydrous lime (CaO) was chosen to remove ammonia from TES
as it is the cheapest source of alkali to produce hydroxide ions (OH-), which can convert
ammonium ions in the sludge to ammonia gas (released).
Several pre-treatment methods listed below had been tried:
Method A: The as received sludge were pre-dried at 105ꢀfor 24 h, and then ground
manually to fine particles smaller than 5 mm in size (Figure 2). The particle size
distribution was determined and the results are presented in Table 2. The prepared TES
was used for making the blocks similar to the reference sample;
Method B: The prepared TES from process A was mixed with lime before concrete
blocks casting. Before mixing with cement and aggregates, the TES was mixed with lime
and water for 5 min using a planetary mixer, with a proportion of TES: lime: water = 1:
0.25: 0.6;

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Method C: The prepared TES from process A was mixed with lime for 5 min with a
proportion of TES: lime: water = 1: 0.25: 0.6; and then the mixture were aged for 24 h in
the laboratory (23±2 , 65±10%RH) before concrete blocks casting;
Method D: The as received TES was mixed with lime for 5 min with a proportion of TES:
lime = 1: 0.07, and then the mixture were aged for 24 h in the laboratory environment
(23±2 , 65±10%RH) before concrete blocks casting.
The basic route for the all pretreatment methods is sketched in Figure 3. After the
pretreatment process, the NH4-N concentrations of the pretreated sludge were also
determined using the HACH Method 8155 (Hach Company, 2003).
2.3 Concrete Block Casting
2.3.1 Mix proportions of concrete blocks
Four series (A, B, C and D) of concrete block mixes were designed to reuse the sludge
corresponding to the four pretreating method of TES mentioned above.
The cement used was ASTM Type I Portland cement. Crushed fine granite passing 5mm
sieve was used as the fine aggregate, while the crushed granite with a nominal size of
10mm was used as the coarse aggregate. Aggregate to cement ratios (A/C) of 6, 10 and
12 were adopted. The pretreated sludge was used to replace the fine aggregate with
different mass ratios. The amount of water added varied slightly with the different mixes,
and was dependent on the amount of pretreated sludge (normally the pre-treated TES had
a higher water demand than natural aggregates) used. The details of mix proportions for
concrete blocks are presented in Table 3.
2.3.2 Fabrication of concrete blocks
The experimental procedure of concrete blocks casting is illustrated in Figure 4.
Specimens with dimensions of 70mm ×70mm ×70mm, and 25mm ×25mm ×285mm were
prepared for the determination of compressive strength and drying shrinkage. Once the
mixing procedure was completed, the mixed materials were cast into steel molds in three
layers. The amounts of materials for each sample were determined by the mold internal
volume and the target density of blocks. After each of the first two layers was filled,

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compaction was applied manually using a hammer and a wooden stem. After the third
layer was filled, a compressive force with a pressure of 30 MPa was applied for about 30
s to mechanically compact the mix within the mold. The excess materials were then
removed with a trowel. The fabricated blocks, in the steel molds, were covered by a
plastic sheet and left in the laboratory environment (23±2 , 65±10%RH) for 24 h, and
then demolded. The samples for compressive strength testing were wrapped by plastic
films for moist curing; the samples for drying shrinkage testing were put into a drying
shrinkage chamber (20ꢀ, 50%RH) after 28-day standard moist curing.
2.4 Test Methods
Compressive strength tests were conducted after 7 and 28 days of moist curing, in
accordance with the procedures described in BS EN 12390-3 (BSI, 2009). The drying
shrinkage test was determined using the method specified in BS 6073 (BSI, 2008).
Furthermore, considering the presence of heavy metal in the textile effluent sludge, the
toxicity characteristic leaching procedure (TCLP) was performed using the fractured
particles from an optimum mix according to the US EPA Method 1311(U.S. EPA, 1990).
The fractured particles after the compressive strength testing at 28 day and were crushed
to pass through a 10 mm sieve. 20 g of crushed sample was put into 400 ml of the TCLP
leachant (prepared by diluting 5.7 mL of glacial acetic acid in 2 L of distilled water) for
tumbling 18 h in a rotary mixer. The mental concentration in the leachate was then
determined using an inductively coupled plasma-optical emission spectral photometer
(ICP).
3. Results and discussion
3.1 Compressive strength
The compressive strength for all the samples after 7-day and 28-day curing age are shown
in Table 4.
For the samples in Series A, there was a significant reduction in compressive strength
after adding the TES into the blocks. Even only 10% of fine aggregate was replaced by
TES (A-10), the 7-day compressive strength was reduced by almost 80% while the 28-

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day compressive strength was reduced by 70%, compared to the reference samples (A-
00). Further increase in TES dosage in the concrete blocks had little impact on the
compressive strength. However, except the reference sample, the 7-day compressive
strength of the samples in Series A did not meet the minimum requirement of 7 MPa
according to BS 6073-1.
When 5% of fine aggregate was replaced by TES, the B-05 samples attained a
satisfactory compressive strength value after 7 days moist curing, which was
considerably higher than 7 MPa. Nevertheless, even after 28-day curing, the compressive
strength of B-10 and B-15 samples was still around 4.4 MPa.
Both two mixes in Series C were prepared with 10% fine aggregate substituted with TES,
but with different aggregate to cement ratios. Apparently, the compressive strength value
for concrete blocks (C-10S) after 7-day and 28-day curing was acceptable once an
aggregate to cement ratio of 6 was adopted. While 7-day compressive strength of
concrete blocks with an aggregate to cement ratio of 10 (C-10T) failed to meet the
minimum requirement of 7 MPa.
For the concrete blocks in Series D, only the 7-day compressive strength for concrete
blocks prepared with 10% fine aggregate replaced with pretreated TES was higher than
the minimum of 7 MPa. However, after 28 days curing age, the compressive strength far
exceeded 7 MPa even 20% fine aggregate was replaced with TES.
3.2 Drying shrinkage
Adoption of concrete blocks with smaller drying shrinkage can lead to a reduction in
probability of developments of drying-shrinkage cracks of masonry walls. The 14-day
drying shrinkage values for all the samples are listed in Table 4. Apparently, partial
replacement of fine aggregate with pretreated TES resulted in a significant increase in 14-
day drying shrinkage of the concrete blocks. For the blocks in Series A and B, the 14-day
drying shrinkage values of all the samples were beyond the maximum allowable values
of 0.060%, as prescribed in BS 6073. The drying shrinkage value even reached 0.1142%
when 30% of fine aggregate in concrete blocks (A-30) were replaced with TES. As
shown in Figure 5, a comparison of drying shrinkage value was made between the

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concrete blocks containing TES with different pretreating methods. It was important to
note that, regardless of the aggregate to cement ratio, there is no discoverable connections
between the drying shrinkage and TES content of concrete blocks. However, the drying
shrinkage values for the samples in Series C and D-10 were still acceptable.
3.3 Metal leaching
Taking into account of maximizing the TES utilization in concrete blocks and easy
operation of TES pretreatment, the sample D-10 was selected as the optimum mix based
on the testing results of mechanical property and volume stability. Two batches of
fractured particles were collected from specimen D-10 and 3 measurements were made
for each batch. The results are listed in Table 5. Compared with the maximum allowable
values given by US EPA, none of them exceeded the limits, even the most abundant
elements (Cu, Pb, Zn) presented in the as received TES. Therefore, the toxic trace metals
present in textile effluent sludge could be stabilized/solidified and metal leaching from
the concrete blocks is not a concern.
3.4 Discussion
According to the results tabulated in Table 4, it can be easily noticed that the compressive
strength of concrete blocks (Series A, B and D) was reduced with the increase in
replacement ratio of fine aggregate with the pretreated TES. However, given the use of
different aggregate to cement ratios for samples in Series A, B and D, it is inappropriate
to compare the compressive strength of concrete blocks directly. In order to give a
quantitative measure of the effect of pretreatment of TES on the mechanical property of
the concrete block, a strength loss factor (f) is defined as:
f = (1- σr/σ) × 100%
(1)
Where, σr is 28-day compressive strength of concrete blocks prepared with the pretreated
TES, while σ is 28-day compressive strength of concrete blocks without TES (ref). Thus,
f ranges from 0 to 100% as σr is always smaller than σ for the samples in the same series.
Figure 6 plots the variation of (f) vs. the mass percentages of the pretreated TES in the
concrete blocks from Series A, B and D. It can be seen that samples in Series D had the
lowest strength loss. Combining the results of NH4-N concentration in the pretreated

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sludge in Figure 7, it can be inferred that that the NH4-N in the TES might have
weakened the mechanical properties of the concrete blocks. A previous study (Kim et al.,
2007) indicated that use of fly ash with high levels of ammonia could dramatically lower
the compressive strength of cement mortar and concrete. Furthermore, due to the
presence of ammonia, the setting time of the cement mortar was delayed when the
amount of ammonia contaminated fly ash was increased. Microscopic analysis also
showed that the presence of ammonia in the fresh concrete mixture suppressed the
formation of calcium silicate hydrates and ettringite, both of which are important cement
hydration products. The NH4-N concentration of TES pretreated with method A, B, C and
D decreased gradually (Figure 7) and as a result, the loss of compressive strength of the
concrete blocks with lower NH4-N concentrations were lower, as shown in Figure 8 (σr(B-
10)ꢁ σr(C-10T), σr(C-10S)ꢁ σr(D-10)). The sludge pretreated with method D had the lowest
NH4-N concentration, making the concrete blocks in Series D achieved the lowest
strength loss.
4. Conclusion
Based on the results and discussion presented above, it can be concluded that it is feasible
to reuse the textile effluent sludge for producing non-load bearing concrete blocks with
acceptable compressive strength and volume stability when appropriate pretreatment
processes are used. It is a fact that the compressive strength of the concrete blocks
decreased significantly with the increase of TES content. The experimental results
indicated that the ammonia level in TES was the main cause of the weakening effects.
The lime pretreatment process proposed in this study can dramatically lower the NH4-N
concentrations and improve the properties of the blocks. The toxic trace metals present in
textile effluent sludge can be stabilized well by cement hydration products.

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Reference:
Balasubramanian, J., Sabumon, P.C., Lazar, J.U., Ilangovan, R., 2006. Reuse of textile
effluent treatment plant sludge in building materials. Waste Manage. 1, 22-28
Batchelor, B., 2006. Overview of waste stabilization with cement. Waste Manage. 7, 689-
698
BSI, 2009. BS EN 12390-3: Testing hardened concrete Part 3: Compressive strength of
test specimens
BSI, 2008. BSI BS 6073-2: Precast concrete masonry units – Part 2: Guide for specifying
precast concrete masonry units
Francisco, B., Pedro, G., Jordi, P., José M. S., 2014. Portland cement systems with
addition of sewage sludge ash. Application in concretes for the manufacture of blocks. J.
Clean. Prod. 82, 112-124
Gencel, O., Ozel, C., Koksal, F., Erdogmus, E., Martínez-Barrera, G., Brostow, W., 2012.
Properties of concrete paving blocks made with waste marble. J. Clean. Prod. 1, 62-70
Gencel, O., Sutcu, M., Erdogmus, E., Koc, V., Cay, V.V., Gok, M.S., 2013. Properties of
bricks with waste ferrochromium slag and zeolite. J. Clean. Prod. 0, 111-119
Hach Company, 2003. Method 8155, Salicylate Method (Ammonia)
Hema, P., Suneel, P., 2009. Exploring the Reuse Potential of Chemical Sludge from
Textile Wastewater Treatment Plants in India-A Hazardous Waste. American Journal of
Environmental Sciences. 1, 106-110
Herek, L.C.S., Hori, C.E., Reis, M.H.M., Mora, N.D., Tavares, C.R.G., Bergamasco, R.,
2012. Characterization of ceramic bricks incorporated with textile laundry sludge. Ceram.
Int. 2, 951-959
Ingunza, M.D., Duarte, A.L., Nascimento, R.M., 2011. Use of Sewage Sludge as Raw
Material in the Manufacture of Soft-Mud Bricks. Journal of Materials in Civil
Engineering. 6, 852-856
Karamalidis, A.K., Voudrias, E.A., 2007. Cement-based stabilization/solidification of oil
refinery sludge: Leaching behavior of alkanes and PAHs. J. Hazard. Mater. 1-2, 122-135
Karthikeyan, J., Mohan, S. V., 1999. Color pollution control in textile industry effluents:
a review advances in industrial pollution control. Techno Science Publications, Karad

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Khatri, A., Peerzada, M.H., Mohsin, M., White, M., 2014. A review on developments in
dyeing cotton fabrics with reactive dyes for reducing effluent pollution. J. Clean. Prod. 87,
50-57
Kim, J.K., Cho, S.D., Lee, H.D., Kim, S.C., 2007. Effect of Ammonia Concentration on
the Utilization of ACFA (Ammonia Contaminated Fly Ash) as an Additive in Mortar and
Concrete Mixture. Journal of Industrial and Engineering Chemistry. 6, 932-938
Ling, T., Poon, C., 2014. Use of recycled CRT funnel glass as fine aggregate in dry-
mixed concrete paving blocks. J. Clean. Prod. 68, 209-215
Noorjahan, C.M., 2011. Physicochemical Characterization Of Untreated Textile Effluent
And Its Effects On Biochemical Constituents Of Fresh Water Fish, Tilapia Mossambica.
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Pandey, S., Pate, H.L., Johri, R., 2011. Global Risk-Based Management of Chemical
Additives I: Production, Usage and Environmental Occurrence, in: The Handbook of
Environmental Chemistry. Springer-Verlag Berlin Heidelberg, Germany, pp. 183-206
Paul, S.A., Chavan, S.K., Khambe, S., 2012. Studies on Characterization of Textile
Industrial Waste Water in Solapur City. International Journal of Chemical Sciences. 2,
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Raghunathan, T., Gopalsamy, P., Elangovan, R., 2010. Study on Strength of Concrete
with ETP Sludge from Dyeing Industry. International Journal of Civil & Structural
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Rala, A., Kalla, P., Csetenyi, L.J., 2015. Sustainable Use of Marble Slurry in Concrete. J.
Clean. Prod. doi:10.1016/j.jclepro.2015.01.053
Tay, J.H., 1987. Bricks Manufactured From Sludge. Journal of Environmental
Engineering. 2, 278-284
U.S. EPA, 1990. Test Method 1311: Toxicity Characteristic Leaching Procedure.
Xu, W., Xu, J., Liu, J., Li, H., Cao, B., Huang, X., Li, G., 2015. The utilization of lime-
dried sludge as resource for producing cement. J. Clean. Prod. 83, 286-293

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List of Figures
Figure 1. Raw textile effluent sludge
Figure 2. Ground TES (＜ 5mm) after oven-dried

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Figure 3. Sketch of pretreatment methods for TES
Figure 4. Fabrication of concrete blocks in lab

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D-10
A/C=6, TES=5.6%
A/C=6, TES=5.6%
C-10S
A/C=10, TES=5.0% C-10T
A/C=10, TES=5.9%
A/C=12, TES=6.0%
B-10
A-10
0
0.02
0.04
0.06
0.08
Drying shrinkage value, %
Figure 5. Comparison of drying shrinkage value of concrete blocks from different series
100.0
80.0
60.0
Series A
Series B
Series D
40.0
20.0
0.0
0.0
5.0
10.0
15.0
20.0
Sludge content in concrete blocks, %
Figure 6. Strength loss (f) against sludge content in concrete blocks

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1800
1500
1200
900
600
300
0
1692
894
451
335
169
Original
A
B
C
D
Sludge samples
Figure 7. NH4-N concentration in sludge pretreated with different methods
50
43.3
40
35.6
30
20
10
0
16.9
4.5
B-10
C-10T
C-10S
D-10
Samples ID
Figure 8. Comparison of compressive strength of concrete blocks containing TES
pretreated with different methods

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List of Tables
Table 1 Characterization of TES
2
Value
(mg/Kg dry
mass)
Value
Trace
1 Oxides
(% dry mass)
metals
Al2O3
SiO2
6.20
3.40
2.79
24.95
0.87
0.53
0.82
60.45
Ag
As
Ba
Cd
Cr
Cu
Hg
Ni
Pb
Se
Si
< 1
< 5
P2O5
SO4
46.83
18.39
110.01
455.11
< 5
CaO
TiO2
MnO
Fe2O3
Others
63.38
304.04
< 2
Water Content (% wet weight)
3 Loss-on-ignition (% dry mass)
4 NH4-N (mg/kg wet weight)
5 Specified gravity (oven-dried)
75.24
11.81
1692
1.14
26.48
291.40
Zn
1: The oxides are determined using X-Ray Fluorescence (XRF) method.
2: Trace metals are determined according to US EPA Method 200.7.
3: Loss on ignition is determined according to BS EN 12879.
4: NH4-N concentration is measured using the HACH Method 8155.
5: Specified gravity is determined using pyknometers according to BS 733-2.
Table 2 Particle size distribution of pre-dried TES
Mass
retained, g
Percentage
retained, %
Cumulative percentage
passing, %
Sieve size
5mm
0
0.0
6.9
100.0
93.1
74.4
44.1
19.0
6.3
2.36mm
1.18mm
17.8
47.9
77.9
64.3
32.5
10.0
6.3
18.7
30.3
25.0
12.7
3.9
600
300
150
ꢀm
ꢀm
ꢀm
75ꢀm
2.5
＜
75
ꢀm
2.5
/

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Table 3 Mix proportions for concrete blocks prepared with TES
Pre-
treatment
method of substituted
TES
% of fine
aggregate
Aggregate
to cement Cement
ratio
Fine
Coarse
Series Notation
aggregate aggregate
with TES
A-00
0
A-10
A-20
A-30
B-00
B-05
B-10
B-15
C-10S
C-10T
D-00
D-10
D-15
D-20
10
20
30
0
Series
A
A
12
10
1
1
7.8
6.5
4.2
3.5
5
Series
B
B
C
D
10
15
10
10
0
10
15
20
6
1
1
3.9
6.5
2.1
3.5
Series
C
10
Series
D
6
1
3.9
2.1
Table 4 Properties of concrete blocks prepared with TES
Compressive strength, MPa
14-day drying
shrinkage value, %
Series
Notation
7-day
23.6±1.0
5.1±0.5
3.1±0.1
2.9±0.2
27.6±1.3
19.1±0.5
2.7±0.2
2.3±0.2
22.8±1.3
6.3±2.1
--
28-day
25.6±1.0
8.4±0.3
4.8±0.3
4.3±0.3
34.2±1.3
23.4±0.2
4.5±0.1
4.4±0.3
35.6±2.5
16.9±0.8
52.1±0.2
43.3±0.7
A-00
A-10
A-20
A-30
B-00
B-05
B-10
B-15
C-10S
C-10T
D-00
D-10
0.0451±0.0021
0.0705±0.0013
0.0926±0.0040
0.1142±0.0031
0.0604±0.0012
0.0688±0.0023
0.0677±0.0038
0.0789±0.0027
0.0495±0.0020
Series A
Series B
Series C
0.0589±0.0013
--
0.0477±0.0020
30.3±1.1
5.9±0.3
2.9±0.3
28.7±0.8
23.3±1.1
Series D
D-15
D-20
--
--

ACCEPTED MANUSCRIPT
Table 5 TCLP results of concrete blocks containing TES
Batch 1
Mean value,
Batch 2
Mean value,
Limits
(mg/L)
Elements
1RSD, %
RSD, %
mg/L
mg/L
Ag
As
Ba
Cd
Cr
5.0
5.0
0.01
2.5
---
0.01
1.8
---
< 0.1
0.31
< 0.1
0.32
100.0
1.0
1.0
---
1.0
---
< 0.01
0.02
< 0.01
0.01
5.0
4.0
8.1
---
1.3
1.2
---
Cu
Hg
Ni
1.0
0.11
0.10
0.2
< 0.1
0.03
< 0.1
0.03
1.0
5.0
---
1.1
---
Pb
Se
5.0
< 0.1
0.07
< 0.1
< 0.05
0.01
1.0
23.7
0.3
---
Zn
5.0
0.01
0.7
1: RSD - Relative standard deviation

ACCEPTED MANUSCRIPT
Highlights:
• Textile effluent sludge (TES) was recycled for producing concrete blocks.
• Lime pretreatment methods were adopted to remove the ammonium in TES.
• TES reduced strength and increased drying shrinkage of concrete blocks.
• Acceptable performance for concrete blocks containing 10% TES was achieved.
• Toxic trace metal in TES could be stabilized in concrete blocks.