Page 9 - ICJ Jan 2026

TECHNICAL PAPER

200.00 80.0
70.0
strength(MPa) 150.00 60.0

50.0
100.00
40.0
Compressive 50.00 Compressive strength (MPa) 30.0
20.0

0.00 10.0
0.25 0.35 0.45 0.0 0.2 0.3 0.4 0.5
W/C ratio W/C ratio
3day 7days 28 days 56 days 3day 7days 28 days 56 days
90 days 150days 180days 90 days 150days 180days
Figure 6: Compressive strength v/s w/c ratio relationship for cement Figure 7: Compressive strength v/s w/c ratio relationship for OPC sand
paste with no-fly ash (F = 0) mortar

200.00 120.0
Compressive strength (MPa) 100.00 Compressive strength (MPa) 80.0
100.0
150.00

60.0

40.0
50.00

0.0
0.00 20.0 0.25 0.3 0.35 0.4 0.45 0.5
0.25 0.3 0.35 0.4 0.45 0.5
W/(C+F)ratio W/(C+F) ratio
3day 7days 28 days 56 days 3 days 7 days 28 days 56 days
90 days 150days 180days 90 days 150 days 180 days
Figure 8: Compressive strength v/s W/(C+F) ratio relationship for F/C Figure 9: Compressive strength v/s W/(C+F) ratio relationship for F/C
ratio = 0.2 cement fly ash paste ratio = 0.2 cement fly ash sand mortar

systems at significantly higher dosages. Higher dosages result in along with the rapid development of semiconductor technology
enhanced electro-static dispersion of cement particles leading from the 1950s onward led to a high demand for silicon, the
to a greater reduction in water demand for a given plasticity, cheapest semiconductor element. The production of silicon
hence w/c could be lowered to attain higher strengths than metal and ferrosilicon alloys produced SF as a by-product. In
were previously attainable [1,23,24] . this process, quartz is heated to about 2200 °C to produce
silicon metal, and the resulting fume when condensed yields
Driven by environmental concerns and the need for cost an ultrafine material containing up to about 95 % amorphous
reduction of cement, the use of pozzolans as partial replacement silica. SF exhibits exceptionally high pozzolanic reactivity
of OPC clinker in cement was rediscovered during the 1960s. and outstanding pore-filling capability in hydrated OPC
Fly ash (FA) a pozzolana, ground granulated blast furnace slag paste, leading to significant refinement of the pore structure.
(GGBFS) etc. were increasingly used as mineral admixtures. Concurrently, advances in polymer chemistry led to the
They did not enhance the achieved strength but contributed to development of graft polymers, culminating in polycarboxylate
the development of a denser micro-structure in the hardened ether (PCE)-based comb-type superplasticizers. These polymers,
paste by converting calcium hydroxide (CH) into C-S-H gel, thus formed by grafting suitable side-chain radicals onto a long
enhancing the long-term performance of concrete . polymer backbone, enhance dispersion of cementitious
[25]
particles primarily through steric hindrance effects. The resulting
A breakthrough in concrete strength came through with the improvement in dispersion enables a further reduction in water
introduction of a highly reactive pozzolana, namely silica fume demand. These two developments together with application
(SF), also known as condensed micro silica. The invention of of particle-packing concepts [26,27] led to development of high
solid-state devices such as transistors and integrated circuits, strength concrete (HSC), reactive powder concrete (RPC),

14 THE INDIAN CONCRETE JOURNAL | JANUARY 2026