Page 5 - ICJ Feb Openaccess 2026

TECHNICAL PAPER

[5]
[9]
durable option for a wide range of structural applications . IS: 456 (2000) , and Conplast SP430, a superplasticizer, was
added to improve workability. The M30 grade concrete mix
This study chose pumice lightweight aggregate for its ability [IS: 10262 (2009) ] showed optimal properties with a 50 %
[10]
to notably decrease the weight of concrete while maintaining pumice replacement. The inclusion of pumice reduced the
sufficient strength for structural applications. The learning concrete density, resulting in lightweight aggregate concrete
explores the profound effects of incorporating pumice that could replace natural aggregates to lower the concrete’s
lightweight aggregate as a partial substitute for traditional
coarse aggregates in M30 and M50 concrete mixes. By self-weight. Due to pumice’s high porosity, superplasticizers
investigating the impact of different pumice aggregate were necessary to manage its increased water absorption.
replacement levels across concrete grades, this research seeks Compressive, split tensile, and flexural strengths were
to determine the optimal mix ratios that enhance weight maximized at a 50 % pumice replacement, with higher levels of
reduction benefits without compromising essential mechanical pumice leading to decreased strengths. This type of concrete
properties. The results could provide crucial insights for creating proved suitable for non-load-bearing wall panels in precast
more efficient, sustainable, and robust construction materials buildings, as well as for lintels, sunshades, partition walls, and
[11]
suited to the changing demands of the building industry. The structures designed to resist earthquakes .
compressive strength test was carried out to rigorously evaluate
the concrete’s ability to endure significant loads without failing, Another study assessed how different concentrations of
which is vital for determining the structural soundness of the magnesium sulfate (0, 2, and 4 %) affect the microstructure and
material. Moreover, split tensile strength tests were performed strength of lightweight mortars containing 15 % fly ash and
to ascertain the concrete’s robust resistance to tensile 10 % silica fume. After a 28 day water cure, the specimens were
stresses, a crucial factor in preventing catastrophic cracking exposed to magnesium sulfate for one year. Microstructure
and ensuring exceptional long-term durability. Additionally, was analyzed using SEM, EDX, and XRD, revealing that higher
the modulus of rupture test was conducted to measure the sulfate concentrations increased porosity and caused more
concrete’s remarkable flexural strength, which is indispensable microstructural damage, especially in pumice aggregate-based
for understanding its superior performance under bending mortars. EDX results showed notable changes in calcium and
loads. Durability assessments and microstructural analysis using silica content, while XRD analysis indicated varying levels
scanning electron microscopy (SEM) and energy dispersive x-ray of gypsum and calcite formation, dependent on sulfate
spectroscopy (EDS) further confirm the suitability of pumice concentration and admixture type. Compressive strength
aggregate as a replacement for normal coarse aggregate in tests indicated that mortars with silica fume exhibited superior
producing structural lightweight aggregate concrete. durability and mechanical properties compared to those with fly
ash or without admixtures .
[8]
2. LITERATURE
A study evaluated the physio-mechanical and durability
In a study on M20 grade concrete, researchers replaced properties of C-25 concrete by partially replacing cement with
conventional coarse aggregates with lightweight pumice blends of bamboo leaf ash (BLA) and pumice powder (PP). With
aggregates and substituted cement with silica fume at 0, 5, PP and BLA categorized as class N and F pozzolans respectively,
8, 10, 15, and 20 %. They observed that compressive strength PP has a combined main oxide content (SiO 2 , Al 2 O 3 , Fe 2 O 3 ) of
improved with up to 10 % silica fume replacement before 84.59 %, while BLA has 74.4 %. The study tested various cement
decreasing. This trend was also noted in cylinder compressive replacement percentages (5 %, 10 %, 15 %, and 20 %) across
strength, split tensile strength, flexural strength, and slab different concrete mixes: Mix-1 (100 % OPC, 0 % PP, 0 % BLA),
moment carrying capacity. Concrete with 100 % pumice content Mix-2 (90 % OPC, 5 % PP, 5 % BLA), Mix-3 (85 % OPC, 10 %
achieved a compressive strength of 8.73 MPa. An increase PP, 5 % BLA), Mix-4 (85 % OPC, 5 % PP, 10 % BLA), and Mix-5
in pumice content led to greater deflections in beams and (80 % OPC, 10 % PP, 10 % BLA). The concrete was mixed with a
slabs. The study concluded that pumice lightweight aggregate cement, sand, and aggregate ratio of 1:2.34:2.68 and a water-to-
performed comparably to other manufactured aggregates such cement ratio (w/c) of 0.491. The findings reveal that workability
[6]
as cold bonded and sintered artificial aggregates .
decreases with increasing PP and BLA content. On day 28, Mix-2
In another study, Ordinary Portland Cement of 43 grade (35.84 MPa) and Mix-3 (33.55 MPa) met the C-25 concrete’s
[7]
IS: 12269 (1987) was used as the primary binding material, required mean compressive strength of 33.5 MPa, as specified
[8]
with fine aggregate (M-Sand as per IS: 383 (1970) filling the by ACI standards. Furthermore, Mix-2, with a flexural strength
voids between coarse aggregates. Coarse aggregate met of 3.86 MPa, satisfied the C-25 ACI minimum requirement of
IS: 383 (1970) standards, while pumice, a natural lightweight 3.5 MPa. It also exhibited lower water absorption and better
[8]
aggregate, required a 24-hour soaking period due to its resistance to sulfuric acid attacks compared to the control mix,
[13]
high-water absorption. Water used in the mix conformed to which experienced a 33.34 % reduction in strength .

56 THE INDIAN CONCRETE JOURNAL | FEBRUARY 2026