Page 10 - ICJ Jan 2026

TECHNICAL PAPER

concrete demonstrated optimized strength-permeability 3.10 Test methods of fresh and hardened
balance through controlled porosity and limited fine content; concrete
plastic concrete exhibited enhanced ductility and ultra-low
permeability with increasing bentonite incorporation, supporting There was a pressing need to develop and standardize
its use in cut-off walls and seepage control; and CLSM mixes, test methods for fresh and hardened concrete that capture
formulated with exceptionally high fly ash volumes, delivered the unique rheology, mechanical behaviour, and durability
self-compacting, low-strength, low-permeability performance performance of self-compacting, 3D-printable concrete, HPC,
[35]
ideal for sustainable backfilling and utility bedding . Mix UHPC, and other next-generation concretes. Novel rheological
Design philosophy and methodology for pervious concrete frameworks were developed to characterize flow, setting, and
was adopted in IRC44 based upon the research work done at early-age stiffness evolution. These studies supported revision
NCCBM. of IS: 1199 to revised test procedures for workability, setting
characteristics. The studies also lead to the revision of IS: 516,
3.8 Roller compacted concrete with inclusion of new standards associated with mechanical
properties of concrete such as flexure, compression, direct
Roller Compacted Concrete (RCC) refers to a special class of tensile strength and durability assessment of concrete through
concrete, which is compacted by the vibratory rollers. RCC, tests like depth of water penetration, oxygen permeability,
which uses the same basic ingredients as conventional concrete carbonation resistance etc. As an outcome of NCCBM’s research
but in different proportions, commonly incorporates high work, IS: 1199 has been revised and published in 7 Parts as
volumes of fly ash to replace Portland cement (PC), while the (a) Part 1-Sampling of Fresh Concrete, (b) Part 2-Determination
use of limestone remains limited despite its role as both an inert of Consistency of Fresh Concrete, (c) Part 3-Determination
filler and a minor reactive component. Studies carried out at of Density of Fresh Concrete, (d) Part 4-Determination of Air
NCCBM [27, 28] evaluate optimal PC replacement levels using fly content of Fresh Concrete, (e) Part 5-Making and Curing of Test
ash and limestone to develop high‑volume fly ash RCC mixes Specimens, (f) Part 6-Tests on Self Compacting Concrete, and
suitable for dam construction in India. Seventeen mixes were (g) Part 7-Determination of Setting Time of Concrete by
prepared with up to 72 % PC replacement using two fly ash Penetration Resistance. Additional guidance has been
types and two limestone sources, and their fresh properties incorporated in Part 5 to specify preferred methods of
(Vee-Bee time, density, setting time) and compressive strengths compaction based on slump requirements, with particular
(7‑180 days) were assessed. Ternary mixes containing OPC, fly emphasis on Self-Compacting Concrete (SCC) and Fiber-
ash, and limestone showed setting times intermediate to those Reinforced Concrete (FRC). Furthermore, Part 6 introduces
of binary mixes and exhibited superior strength at all ages due standardized test methods applicable to SCC, ensuring uniform
to synergistic effects. Results indicate that 365-day strength is evaluation of its fresh and hardened properties. Some of the
nearly double the 28-day strength, admixtures have negligible revised IS: 516 standards are (a) IS: 516 Part 1/Section 1-Testing
influence on compressive strength, and finer fly ash enhances of Strength of Hardened Concrete-Compressive, Flexural and
long-term strength, with all mechanical and thermal properties Split Tensile Strength, (b) IS: 516 Part 4-Sampling, Preparing and
aligning with Indian Standards and international data. Testing of Concrete Cores, (c) IS: 516 Part 6-Drying Shrinkage
and Moisture Movement, (d) IS: 516 Part 8/Section 1-Modulus of
3.9 Thermal Properties on concrete and Elasticity and Poisson’s Ratio (Static), (e) IS: 516 Part 11-
temperature control of mass concrete Determination of Portland Cement Content of Hardened
Concrete, (f) IS: 516 Part 5/Section 1-Ultrasonic Pulse Velocity
NCCBM has conducted extensive studies on the thermal (UPV) Test, (g) IS: 516 Part 5/Section 3-Carbonation Depth
properties of mass concrete for several hydroelectric projects, Test, (h) IS: 516 Part 5/Section 4-Rebound Hammer Test. To
including the Dhaulasidh, Arun-3, and Luhri H.E. Projects. It has facilitate comprehensive assessment of concrete durability,
also carried out temperature-control investigations for projects several standardized test methods have been incorporated into
such as the Tanahu and Dibang H.E. Projects. The thermal IS: 516 for evaluating key performance parameters, they are as
studies involved evaluating concrete mixes for key parameters (a) Water permeability test-IS: 516 Part 2/Section 1, (b) Initial
like coefficient of thermal expansion, specific heat, thermal Surface Absorption test-IS: 516 Part 2/Section 2, (c) Oxygen
conductivity, and thermal diffusivity using the Transient Plane permeability index-IS: 516 Part 2/Section 3, (d) Carbonation
Source (TPS) method, while the temperature-control studies resistance of hardened concrete by accelerated carbonation
included semi-adiabatic temperature-rise measurements on method-IS: 516 Part 2/Section 4, (e) Half-cell Potential Test-
various concrete mixes. However, based on these studies, IS: 516 Part 5/Section 2. This breakthrough in the standardization
it has been found that there is need to revise standards on now makes it possible to explore the impact of innovative
thermal properties of concrete and temperature control of mass cementitious materials and alternative aggregates on concrete
concrete as mentioned in section 4.5 rheology, and to fine‑tune concrete mix proportions for

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