PSI - Issue 70

K. Navin Balaji et al. / Procedia Structural Integrity 70 (2025) 295–302

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effects on concrete properties. The study substituted natural coarse aggregate with Coconut Shell Aggregate at a consistent weight level of 20% in order to create sustainable concrete and lower density. Table 2 outlines the proportions of each mixture. The testing adhered to the stipulations outlined in Indian Standard regulations. The compressive strength, modulus of elasticity and flexural strength tests adhered to the requirements established by IS 516:1959, while the split tensile strength tests conformed to IS 5816:1999. The ultrasonic pulse velocity (UPV) test was performed according to IS 13311 - 1992. Fig.2. depicts several tests performed on SCC specimens.

(c)

(a)

(b)

Fig.2. Test setup; (a) Compressive strength; (b); UPV test; (c) Flexural strength

3. Discussion On Results 3.1 Fresh concrete properties

Various kinds of fresh characteristics of SCC are enumerated in Table 3. All concrete mixtures exhibited slump flow measures ranging from 650 mm to 715 mm, which aligns with the EFNARC-recommended range of 650–800 mm, hence indicating suitable flowability. The control mix (CC) achieved the highest slump flow value of 715 mm but the mix containing 25% RHA replacement exhibited the lowest value of 650 mm indicating workability reduction from increasing RHA content. The high surface area and pozzolanic behaviour of RHA increases water requirements thus affecting workability (Wagh et al.,2022). The addition of 15% LSP to the mixtures improved their flow characteristics throughout by filling spaces between particles and optimizing their arrangement. The mix density decreased by 20% CSA replacement of natural coarse aggregate while also enhancing deformability in the initial mixes. The flow rate of concrete mixtures decreased slightly as RHA content increased, because T500 time expanded from 2.8 to 4.2 seconds and V-funnel time spanned from 9.4 to 11.0 seconds. The passing ability of the mixes became slightly more restricted as the L-box ratio declined from 0.93 to 0.81 and the J-ring blocking step grew from 5.0 mm to 6.8 mm. The fresh property measurements of all SCC mixes met the EFNARC (2005) criteria. Fig.3(a) to 3(d) illustrates the test results on various tests on fresh properties on SCC.

Table 3. Fresh characteristics of SCC with RHA, LSP, and CSA Mix ID Slump Flow (mm) T500 (sec)

L-Box Ratio (H2/H1)

V-Funnel Time (sec)

J-Ring Blocking Step (mm)

CC

715 710 700 690 675 660 650

2.8 3.0 3.2 3.5 3.7 3.9 4.2

0.93 0.91 0.89 0.87 0.85 0.83 0.81

9.4 9.5 9.7 9.8

5.0 5.3 5.5 6.0 6.2 6.5 6.8

RHA-0 RHA-5 RHA-10 RHA-15 RHA-20 RHA-25

10.0 10.5 11.0