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Figure 2: Metro Waste Handling Pvt Ltd C&D recycling facility in Thane

2.3 Material control The sample was analysed at the Bureau Veritas Construction
Services Laboratory in Navi Mumbai. The properties determined
Preparation of the fine RCA sample from the main stockpile for the RCA 0/2 mm are shown in Table 1.
of RCA 0/2 mm was conducted as follows. An area of
approximately 4 × 4 meters in the 1/3 height (from ground) of 3. DESCRIPTION OF THE CONSTRUCTION
the pile was opened with a front end loader. From that opened PROJECT AND THE CONCRETE MIX DESIGN
area, 100 kg was taken manually with a spade ensuring that USED
samples were collected from 10 different sub-places in the 4x4
meter area. The required volume (100 kg) was homogenised L&T Construction has been awarded the CIDCO Housing
by pouring it out on a cleaned concrete floor to prevent Package 4 in Navi Mumbai under the Pradhan Mantri Awas
contamination from the ground and turned upside down (end- Yojana (PMAY). PMAY was launched to provide affordable
over-end) minimum 3 times by the spade. The process was housing for the urban population. The mission of this scheme
conducted gently to ensure that the particles were not crushed. is to provide housing to all in India by the end of 2022. Package
4 is the largest order for construction under the PMAY scheme
Table 1: Overview of the material properties tested and consist of 22400 residential units with a built-up area of
17 million sq. ft. Around 4.5 million sq. ft. in Package 4 is carried
PARAMETER TEST METHOD
out using L&T’s Precast Large Concrete Panel system. For this,
Sieving analysis IS 2386 Part 1 a temporary precast concrete factory with a pre-engineered
Specific gravity IS 2386 Part 3 building shed of about 11000 sq. m. has been constructed at the
site, with a capacity to build 2.2 million sq. ft. of built-up area per
Bulk density IS 2386 Part 3
year.
Moisture content IS 2386 Part 3
Water absorption IS 2386 Part 3 The concrete mix design is specified in Table 2 and was suitably
adjusted to accommodate the higher WA and the finer particle
Particles < 75 µm IS 2386 Part 1
size distribution of fine RCA. This included water compensations
Coal and lignite IS 2386 Part 2 based on the determined WA and the actual moisture content
Clay lumps IS 2386 Part 2 measured at the concrete mixing plant. The target w/b ratio
Reduction in alkalinity IS 2386 Part 7 was 0.50. The particle size of 0/2 mm RCA was used as it was
the available sand fraction at the recycling wet process facility.
Dissolved silica IS 2386 Part 7
Replacement levels of the CSS fractions by RCA 0/2 mm, were
Soundness (Na 2 SO 4 ) after 5 cycles IS 2386 Part 5 50 and 100% for M20 and M10, respectively. The specific gravity
Acid soluble sulphate EN 1744-1: 2009 + A1: 2012 of CSS and fine RCA sand was 2.64 and 2.52, respectively.
Hence, preparing the RAC without changing the fine to coarse
Acid soluble Chloride IS 14959: 2001 Part 2
ratio made an acceptable change in the yield of 0.6%. A total
pH (5% solution) In house method
volume of 494 m was casted with fine RCA. The grade-wise
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THE INDIAN CONCRETE JOURNAL | JANUARY 2022 51