Materials & Mix Design

A specification is a set of numbers, and most of them are ranges. This guide collects the ranges that decide whether a concrete works on site — the cement grades and what separates 43G from 53G from 53S, the replacement levels of fly ash, GGBS and silica fume, the IS 383 grading zones, the admixture doses and the water hiding inside them, the IS 456 Table 5 durability ceilings, and the gap in the codes where ultra-high performance concrete sits.

Every value is labelled: code values are transcribed from a BIS publication and the clause is cited; pract values are this practice's working ranges; no IS / ACI clause marks what no Indian Standard or ACI document covers at all.

Every section of this guide, and the standard it rests on. Open the standard and read it yourself.

Cement — what to specify, and what the code actually requires

Cement choice in India is narrower than it looks. IS 269:2015 (Sixth Revision) consolidates the ordinary Portland range into three grades, and the industry shorthand — 43G, 53G and 53S — is worth understanding before a specification is written.

The suffix means everything in practice: G is the general-purpose grade, S is the sulphate-resistant grade with tighter chemistry and a finer grind. Both 43G and 53G carry a wide lime ratio (0.66–1.02), which is why their strength and consistency vary more between plants than 53S does.

Requirement (IS 269:2015)	OPC 43G	OPC 53G	OPC 53S
Minimum compressive strength, 3 days, MPa	23	27	27
Minimum compressive strength, 7 days, MPa	33	37	37.5
Minimum compressive strength, 28 days, MPa	43	53	53
Fineness, minimum, m²/kg	225	225	370
Initial setting time, minimum, min	30	30	60
Final setting time, maximum, min	600	600	600
Insoluble residue, maximum, %	5.0	5.0	2.0
Magnesia, maximum, %	6.0	6.0	5.0
Loss on ignition, maximum, %	5.0	4.0	4.0
Lime ratio (CaO to SiO₂, Al₂O₃, Fe₂O₃)	0.66–1.02	0.80–1.02	0.80–1.02
Chloride content, maximum, %	0.1	0.1	0.1
Alkali (Na₂O_eq)	see Note 1 — below 0.6 % where the aggregate is reactive

Transcribed from IS 269:2015 Tables 2 and 3. Note 1: where alkali aggregate reaction has been noticed in the region, cement with an alkali content below 0.6 % expressed as Na₂O + 0.658 K₂O is recommended; otherwise the aggregate itself should be tested. Chloride limit is 0.05 % for prestressed structures.

Which grade, when?53G is the default for structural concrete and gives the most consistent 28-day strength. 53S costs little more and is the sensible default for marine, coastal, sulphate-bearing soil or industrial exposure — the finer grind (370 m²/kg) also gives a longer working time, which helps a UHPC or a congested section. 43G is a legitimate choice for mass concrete, blockwork and lean mixes, but it must be accepted on the strength of the plant's own 28-day results, not on the nominal 43 MPa class — the wider lime ratio is where the variability comes from.

Blended cements — Portland pozzolana cement (PPC, IS 1489 Part 1) and Portland slag cement (PSC, IS 455) — are permitted within IS 456 Table 5, but only on the condition that the pozzolana or slag taken into account does not exceed the limit in the relevant standard. The 450 kg/m³ cement-content cap in IS 456 Cl. 8.2.4.2 applies to cement excluding fly ash and GGBS.

Supplementary cementitious materials — replacement levels, and what each one actually buys you

A supplementary cementitious material is not cement. It replaces cement in part, it reacts differently, it releases heat differently, and it changes the shrinkage. The replacement levels below are the ranges this practice uses; the durability consequences are set by IS 456 Table 5, not by the replacement level.

Material	Standard	Typical replacement, % of binder	What it changes	Code or practice
Fly ash	IS 4926 IS 3812 (Part 1)	15–35	Lowers heat and permeability; slower early strength; needs longer curing	practice
Ground granulated blast furnace slag	IS 16714 IS 712	20–50	Lowers heat; improves sulfate and chloride resistance; contributes little to early strength	practice
Silica fume (microsilica)	IS 15388	5–10	Large strength gain at low w/c; very dense matrix; raises autogenous shrinkage and heat	IS 456 Amd 2
Metakaolin	IS 16354	5–15	Refines the pore structure; faster pozzolanic response than fly ash	practice
Calcined clay	—	15–30	Faster strength than fly ash; a lower-carbon clinker substitute	practice

The silica fume range is the one that carries a code figure: IS 456:2000 Amendment 2 (September 2002), Cl. 5.2.1.2 — “Silica fume conforming to IS 15388 may be used as part replacement of cement provided uniform blending with the cement is ensured. NOTE – Silica fume is usually used in proportion of 5 to 10 percent of the cement content of a mix.” The other replacement levels are the ranges this practice uses, not code limits. IS 456:2000 Table 5 Note 1 (as amended in May 2013) allows fly ash and GGBS to be taken into account towards the minimum cement content and the water-cement ratio, but only up to the limits of IS 1489 (Part 1) and IS 455 respectively. IS 456 Amendment 5 (July 2019) brought GGBS into IS 16714 and metakaolin into IS 16354, and added Cl. 5.2.3 on the precautions that the SCMs require — setting time, plastic shrinkage, and compatibility with the chemical admixtures.

The one that surprises peopleSilica fume at 8–12 % of binder is the reason a UHPC can reach 150 MPa at w/b 0.13. It is also the reason that mix is prone to autogenous shrinkage: the pozzolanic reaction consumes the calcium hydroxide and the alkalinity that drive the cement hydration, so the cement hydrates less completely while the paste becomes far denser. Both effects are real and they have to be designed for at the same time.

Aggregates — grading, size and the tests that have to be on the certificate

Fine aggregate — IS 383:2016 Table 9, cumulative % passing

IS sieve	Grading Zone I	Grading Zone II	Grading Zone III	Grading Zone IV
10 mm	100	100	100	100
4.75 mm	90–100	90–100	90–100	95–100
2.36 mm	60–95	75–100	85–100	95–100
1.18 mm	30–70	55–90	75–100	90–100
600 µm	15–34	35–59	60–79	80–100
300 µm	5–20	8–30	12–40	15–50
150 µm	0–10	0–10	0–10	0–15

IS 383:2016 Table 9. For crushed stone sands the permissible limit on the 150 µm sieve is increased to 20 %. A sand whose grading falls near the border of two zones is judged on the finer side (IS 383 Cl. 6.3).

Zone II is the usual default for structural concrete. Zone III suits leaner, lower-strength mixes; Zone I is for pumpable and heavily reinforced work. Zone IV should not be used in reinforced concrete unless tests establish the suitability of the proposed mix proportions.

Coarse aggregate — IS 383:2016 size ranges

Size	IS 383:2016	Typical use	Note
80 – 40 mm	Large	Mass concrete, rubble concrete	Not for reinforced concrete
40 – 20 mm	Medium	General structural use	The 20 mm nominal size that IS 456 Table 5 is written for
20 – 4.75 mm	Small	General structural use	Needs more paste for the same workability
4.75 mm and below	Fine	Used as fine aggregate	Not as coarse aggregate

IS 383:2016 Table 8. The nominal maximum size drives the cement-content adjustment in IS 456 Table 6.

Steel fibre — ACI 544

Steel fibre is the one material on this page that a code does quantify directly, because the dosage is a property of the composite rather than of the mix design. ACI 544.3R gives the range, and ACI 544.4R gives the design consequences.

Parameter	Value	Source
Usual steel fibre content, by volume	0.25 % to 2 % (about 20 to 157 kg/m³)	ACI 544.3R-93
Mass conversion	1 % by volume of steel fibre = 78.3 kg/m³ (132.3 lb/yd³)	ACI 544.3R-93
Low end of the range applies to	Lightly loaded slabs on grade, some precast applications, and composite steel deck toppings	ACI 544.3R-93
High end of the range applies to	Security applications (safes, vaults)	ACI 544.3R-93
Field limit on fibre volume × aspect ratio	v_f · (l/d) ≈ 100 for uniform straight fibres, on workability grounds	ACI 544.4R-88
Fibre length versus reinforcement spacing	The fibre length should not exceed the clear spacing between bars, welded wire fabric, or other embedded material, including the cover	ACI 544.3R-93
Balling	Caused by adding too much fibre — more than about 2 % by volume, or even 1 % of a high-aspect-ratio fibre — and by adding fibre to a stiff mix rather than a fluid one	ACI 544.3R-93
Typical 28-day ultimate flexural strength	6.5 to 10 MPa at 1.5 % fibre by volume for mortars (w/c 0.45–0.55), approaching 13 MPa at 2.5 %	ACI 544.4R-88
Ultimate flexural strength vs ordinary concrete	Of the order of 1.5 times that of ordinary concrete	ACI 544.4R-88

ACI 544.3R-93 and ACI 544.4R-88 are the ACI guidance for steel-fibre reinforced concrete — note they are written for conventional fibre-reinforced concrete, not for UHPC, and the v_f·(l/d) limit in particular is a field workability limit that a high-entropy UHPC mix routinely exceeds with the help of a plasticiser.

Checks that belong on the supplier certificate

Sieve analysis and grading zone — not just a fineness modulus. A single FM number can sit inside two zones.
Water absorption and moisture content — the two numbers that decide whether the batched water is right. Absorption on 10 mm aggregate commonly runs 0.5–1.5 %, on river sand 0.5–1.5 %, on crushed sand 0.5–1.0 %; these are the values this practice measures and corrects against, not code limits.
Deleterious substances — clay, silt, chlorides, sulphates, organic matter, mica. IS 383 Cl. 4 sets the limits.
Strength of the aggregate — crushing value, impact value, abrasion value, and for structural use the modulus of elasticity (IS 383 Cl. 5).
Alkali-silica reactivity — where the cement alkali is above 0.6 % Na₂O_eq, IS 269 Note 1 puts the duty on testing the aggregate.

Chemical admixtures — what to specify and what to watch on site

Admixtures are the most under-specified material on most Indian sites. IS 9103 covers concrete admixtures, and IS 4923 is the newer specification standard. The critical discipline is not the product — it is the solids content and the water the product carries.

Type	Typical dose, % of binder	What it does	What to watch
Plasticiser (PCE / superplasticiser)	0.5–1.5	Increases workability at constant w/c, or reduces water at constant slump	The product is 35–40 % solids — the rest is water, and it counts towards w/c
Superplasticiser (HRWR, second generation)	1.0–2.5	Same, at higher dose and higher water reduction	Overdose causes segregation and bleeding; check the batch water
Retarder	0.2–1.0	Delays setting — for hot weather and long haul	Dose must be checked against the set-time test, not the nominal
Accelerator	0.5–3.0	Shortens setting time; used in cold weather and for rapid turnover	Higher doses can reduce long-term strength
Air-entraining agent	0.02–0.10	Entrains 1–6 % air for freeze-thaw durability	Air content must be measured, and checked after the first production batch
Water-reducing admixture (conventional)	0.5–1.5	Modest water reduction, or slump improvement	Specify the strength of the mix, not the brand
Shrinkage-reducing admixture (SRA)	1.0–2.5	Reduces drying shrinkage, typically 30–50 %	Needs a curing regime that does not negate it
Viscosity-modifying admixture (VMA)	0.1–0.5	Stabilises the mix for pumping and underwater work	Can be dosed into the batch water; must be pre-dissolved

Dose ranges are this practice's working ranges, not code limits. IS 456 Cl. 5.5 requires admixtures to comply with IS 9103 and requires the chloride content of the admixture to be tested independently for each batch.

The water inside the admixtureA conventional superplasticiser dosed at 1.5 % of binder is a 40 % solids product — so roughly 0.9 % of the binder mass arrives as extra water. At a design w/c of 0.35 that moves the effective ratio to about 0.36, and at a UHPC w/b of 0.13 the same effect is proportionally far larger. Always ask the supplier for the solids content, and always subtract the admixture water from the batch water.

Mixing and curing water — the requirement, and what to test

Mixing water shall be clean and free from harmful ingredients that would affect the properties of the concrete or the reinforcement (IS 10262:2019, Cl. 4.2). Potable water is normally acceptable without test. Where a non-potable source is proposed — a borewell, a recycled water line — the project specification governs, and the following are the usual parameters: total solids, sulphates, chlorides, pH, and hardness. The two that cause structural damage rather than surface defects are chlorides (corrosion) and sulphates (reaction with the cement paste).

For curing, IS 456 Cl. 13.5 requires moist curing for at least 7 days for OPC and at least 10 days for blended cements and for mixes containing SCMs, and longer in hot or arid weather. Curing compounds are a permitted alternative only with the engineer's written permission.

Workability — what the code asks for at the point of placing — IS 456:2000 Cl. 7.1

Placing condition	Degree of workability	Slump, mm
Blinding concrete; shallow sections; pavements using pavers; mass concrete; lightly reinforced sections in slabs, beams, walls and columns; floors; hand-placed pavements; canal lining; strip footings	Very low	See Cl. 7.1.1 — compacting factor 0.75–0.80 is suggested
Heavily reinforced sections in slabs, beams, walls and columns	Low	25–75
Slipform work; pumped concrete; trench fill	Medium	50–100
Tremie concrete; in-situ piling	High	75–150
—	Very high	See Cl. 7.1.2

IS 456:2000 Cl. 7.1. For most of these placing conditions internal (needle) vibrators are suitable; the needle diameter is set by the density and spacing of the reinforcement and by the thickness of the section.

How the strength curve is chosen — IS 10262:2019 Fig. 1The figure gives three curves, and they are selected by the concrete’s expected 28-day strength, not by the cement grade: Curve 1 for 33 to < 43 N/mm², Curve 2 for 43 to < 53, Curve 3 for 53 and above. Note 1 maps them to OPC 33, 43 and 53 only as the default when the actual 28-day strength of the cement is unknown, and Note 2 says that for PPC and PSC the curve for the actual strength should be used, defaulting to Curve 2. The chart runs from about 0.21 to 0.65 on the free w/c axis and 0 to 80 N/mm² on the strength axis — so it does not reach ultra-high strength concrete at all, and the separation between the OPC-43 and OPC-53 curves (about 9 to 10 MPa at w/c 0.25–0.30, read off the figure) is not constant across the chart. For a UHPC, the only strength basis that reaches the required strength is a trial-derived regression, and that regression is tied to the cement it was mixed with. IS 10262:2019 Fig. 1, p. 6 (read from the BIS copy).

Mix design parameters — the ranges a proportioning decision should sit inside

These are the working ranges used for a conventional designed mix. The durability ceilings are set by IS 456 Table 5 and always govern: if a design sits outside one of those ranges, the exposure classification and the mix have to be reconciled before the mix is issued.

Parameter	Typical range	Governed by	Note
Free water-cement ratio, w/c	0.30–0.55	IS 456 Table 5 (maximum)	The single most influential variable. Above 0.55 the durability provisions become the binding constraint
Total cement content	250–450 kg/m³	IS 456 Table 5 (minimum), Cl. 8.2.4.2 (maximum 450)	The 450 kg/m³ cap excludes fly ash and GGBS
Cement : fine aggregate : coarse aggregate	1 : 1.5 : 2 to 1 : 2 : 3 (by volume)	IS 456 Cl. 9.3	Nominal mixes are permitted up to M20 only; above that a design mix is required
Fine : coarse aggregate, by mass	0.35–0.45 for pumped work up to 0.45–0.55 for normal work	IS 10262 Table 5	Shift lower when the section is congested or the concrete is pumped
Paste volume	250–350 L/m³	Practice	Above about 350 L/m³ the shrinkage and the heat become design problems
Entrained air	1–3.5 % total (nominal 20 mm, Zone II, 1 %)	IS 10262 Table 3	0.5–1 % for 10 mm, 1 % for 20 mm, 2 % for 40 mm; higher for severe exposure with an air-entraining agent
Water content, 50 mm slump, 20 mm aggregate	about 186 kg/m³	IS 10262 Table 4	Add 3 % per additional 25 mm of slump; reduce for a superplasticiser, then re-check w/c
Concrete grade	M10–M80 as defined in IS 456 Table 2	IS 456	The grade is the 28-day characteristic strength, not the mean
Target mean strength	f_ck + 1.65 S	IS 10262 Table 2	S = 3.5 for M10–M15, 4.0 for M20–M25, 5.0 for M30–M60, 6.0 for M65–M80 for good control

Durability requirements by exposure — IS 456:2000 Table 5 — normal-weight aggregate, 20 mm nominal maximum size

Exposure	Plain: min cement, kg/m³	Plain: max w/c	Plain: min grade	Reinforced: min cement, kg/m³	Reinforced: max w/c	Reinforced: min grade
Mild	220	0.60	—	300	0.55	M20
Moderate	240	0.60	M15	300	0.50	M25
Severe	250	0.50	M20	320	0.45	M30
Very severe	260	0.45	M20	340	0.45	M35
Extreme	280	0.40	M25	360	0.40	M40

IS 456:2000 Table 5, transcribed from the BIS copy and checked against the scanned page. The minimum grade for plain concrete under mild exposure is not specified. For nominal maximum aggregate sizes other than 20 mm, adjust the minimum cement content by +40 kg/m³ at 10 mm, 0 at 20 mm and −30 kg/m³ at 40 mm (IS 456 Table 6). IS 456 Table 5 Note 1 allows fly ash and GGBS to be taken into account towards the minimum cement content and the w/c ratio, within the limits of IS 1489 (Part 1) and IS 455.

Sulphate exposure — IS 456:2000 Table 4

Sulphate is not covered by Table 5. Table 4 gives the cement type that must be used at each sulphate concentration, together with the minimum cement content and the maximum water-cement ratio. The sulphate concentration is expressed as SO₃, measured in the soil, in a 2:1 water-to-soil extract, and in the ground water — all three, because any one of them can govern.

Class	SO₃ in soil, %	SO₃ in 2:1 water:soil extract, g/l	SO₃ in ground water, g/l	Type of cement	Min cement, kg/m³	Max w/c
1	Traces (< 0.2)	less than 1.0	less than 0.3	OPC, or Portland slag cement, or Portland pozzolana cement	280	0.55
2	0.2 to 0.5	1.0 to 1.9	0.3 to 1.2	OPC, or Portland slag cement, or Portland pozzolana cement	330	0.50
2	as above	as above	as above	Supersulphated cement, or sulphate-resisting Portland cement	310	0.50
3	0.5 to 1.0	1.9 to 3.1	1.2 to 2.5	Supersulphated cement, or sulphate-resisting Portland cement	335	0.50
3	as above	as above	as above	Portland pozzolana cement, or Portland slag cement	350	0.45
4	1.0 to 2.0	3.1 to 5.0	2.5 to 5.0	Supersulphated cement, or sulphate-resisting Portland cement	370	0.45
5	more than 2.0	more than 5.0	more than 5.0	Sulphate-resisting Portland cement, or supersulphated cement with protective coatings	400	0.40

IS 456:2000 Table 4, dense fully-compacted concrete with 20 mm nominal maximum aggregate. Table 4 Notes: cement content is irrespective of the grade of cement; supersulphated cement is generally restricted where the prevailing temperature exceeds 40 °C; supersulphated cement gives acceptable life provided the concrete is dense and prepared with w/c ≤ 0.40, and in mineral acids down to pH 3.5; cement contents are minimums — for SO₃ near the upper limit of a class, a higher content is advised; for severe conditions (thin sections under hydrostatic pressure on one side only, partly immersed) a further reduction of w/c should be considered; Portland slag cement with more than 50 % slag has better sulphate resistance; where chlorides are encountered along with sulphates, OPC with C₃A of 5–8 % is desirable instead of sulphate-resisting cement. Separately, IS 456 Cl. 8.2.5.3 limits the total water-soluble sulphate content of the concrete mix to 4 % by mass of the cement in the mix (that limit does not apply to concrete made with supersulphated cement conforming to IS 6909).

Chloride limits, cover and the sea-water rule

Requirement	Value	Source
Total acid-soluble chloride — concrete containing metal and steam cured at elevated temperature, and pre-stressed concrete	0.4 kg/m³	IS 456 Table 7
Total acid-soluble chloride — reinforced concrete, or plain concrete containing embedded metal	0.6 kg/m³	IS 456 Table 7
Total acid-soluble chloride — concrete not containing embedded metal or anything needing protection from chlorides	1.0 kg/m³	IS 456 Table 7
Minimum grade for concrete in sea water or exposed directly along the sea coast	M20 plain, M30 reinforced	IS 456 Cl. 8.2.8
Nominal cover — mild exposure	20 mm	IS 456 Table 16
Nominal cover — moderate exposure	30 mm	IS 456 Table 16
Nominal cover — severe exposure	45 mm	IS 456 Table 16
Nominal cover — very severe exposure	50 mm	IS 456 Table 16
Nominal cover — extreme exposure	75 mm	IS 456 Table 16

IS 456 Table 16 Notes: for main reinforcement up to 12 mm diameter in mild exposure the nominal cover may be reduced by 5 mm; unless specified otherwise the actual cover may run 10 mm over the required nominal cover, but never under it; for severe and very severe exposure a 5 mm reduction may be made where the concrete grade is M35 and above. Cl. 8.2.8 adds that the use of slag or pozzolana cement is advantageous in the sea-water case.

Which standard governs the exposure condition? In India it is IS 456:2000 — Table 3 defines the five environmental exposure conditions (mild, moderate, severe, very severe, extreme) and Table 5 states the minimum cement content, maximum free water-cement ratio and minimum grade for each. IS 10262:2019 works entirely from those two tables. A common mistake is to reach for IS 16700:2023: that standard is Criteria for Structural Safety of Tall Concrete Buildings (First Revision) — RC buildings 50 m to 250 m in height — and it says nothing about exposure or durability. The XC / XD / XS / XF / XA classes are the EN 206-1 (European) system, not an Indian Standard; they are useful shorthand in an international spec, but the requirement that governs here is IS 456 Table 5.

Sulphate is a separate tableSulphate exposure is not in Table 5. IS 456 Table 4 gives the requirements by sulphate concentration — with the cement type that must be used at each level, the minimum cement content and the maximum water-cement ratio. Check Table 4 as well as Table 5 for any sulphate-bearing exposure.

What comes next — the IS 456 Fifth Revision draft — a draft for comments, not a published standard

BIS circulated the Fifth Revision of IS 456 as a Draft for Comments (CED 02(27096)P, 01 January 2025). It replaces the mild / moderate / severe / very severe / extreme system with four families of classes, and it adds electrical resistivity and RCPT as durability acceptance values. It is not yet published, so it cannot be cited in a specification today — but if a project is being designed now and will be built in a few years, it is worth knowing where the code is going.

Family	Classes	What they replace
Carbonation (climate)	C1 hot-dry · C2 warm humid and temperate · C3 composite · C4 cold region	The single mild/moderate axis. C1 is a mean monthly maximum above 30 °C with mean monthly RH below 55 %; C4 is a mean monthly maximum below 25 °C for all RH values
Chlorides other than sea water	CH1 wet, rarely dry · CH2 cyclic wet and dry	Swimming pools and water containing chlorides; bridge parts exposed to chloride spray
Chlorides from sea water	SW1 airborne salt · SW2 permanently submerged · SW3 tidal, splash and spray	SW1 is banded by distance from the coast: up to 1 km, 1–10 km and 10–50 km
Sulphate attack	S0 no risk · S1 moderate · S2 severe · S3 very severe	The sulphate classes of IS 456 Table 4
Freezing and thawing	F1 moderate · F2 severe · F3 very severe	Part of the old severe exposure

Draft Tables 66–70 (classification) and Tables 73, 78, 82, 83 (requirements). The draft also introduces electrical resistivity at 28 days and RCPT charge passed as durability acceptance values, and it specifies the cement type that must be used for each sulphate class. Draft Tables 72 and the notes to Table 73 carry the same cement-content adjustment for aggregate size as the present Table 6. Treat this as a preview, not a code.

Ultra-high performance concrete — and the gap in the codes

There is no Indian Standard and no ACI document that covers UHPC mix design, proportioning, steel-fibre dosage, autogenous shrinkage, creep coefficient, or UHPC durability acceptance. IS 456, IS 10262 and the ACI series stop at high-performance and mass concrete. Anyone presenting an IS 456 Table 5 check as though it were a UHPC acceptance criterion is reading the wrong table.

The UHPC-specific basis is fib Model Code 2010 (fib Bulletin 65) §5.6 (fib Task Group 8.6), the AFGC–SETRA UHPFRC Recommendations (2013), the JSCE recommendations (2006, published as SSCS-2007) and the FHWA UHPC reports. Note: “fib Bulletin 83” is not the UHPC document — it is Precast tunnel segments in fibre-reinforced concrete (fib, 2017)., the JSCE recommendations (2006), and the fib Model Code. The ranges that matter most:

Parameter	UHPC range	Source	Code or practice
Total binder	850–1 200 kg/m³, typically 900–1 100	AFGC–SETRA 2013 Annex 14 Table 1 (900 kg/m³ benchmark); Fehling 827–1 095; FHWA-HRT-18-036 (1 095)	practice
Water / binder (total water)	0.13–0.22, typically 0.15–0.19	AFGC–SETRA 2013 (w/c 0.20, i.e. w/b 0.156); JSCE SSCS-2007 §6.4.4 (w/b 18–22 %); FHWA-HRT-13-060 (w/c ≈ 0.22)	practice
Silica fume, % of binder	10–25 %, typically 15–22 % (about 200–300 kg/m³)	AFGC–SETRA 2013 Annex 14 Table 1 (200 kg/m³ = 22.2 % of binder); Fehling 14–21 %; FHWA-HRT-18-036 (28 %)	practice
HRWR / PCE, % of binder	1.0–3.0 % as the liquid product; 0.33–0.54 % as solids	Fehling & Schmidt 2014 Table 2.1 (1.1–1.2 % as liquid product); AFGC–SETRA 2013 §1.11.2 requires the mix design to state the admixture on a dry-extract (solids) basis — 30–45 % actives by mass of the liquid product	practice
Steel fibre, % by volume	1.0–2.5 % (about 80–200 kg/m³)	AFGC–SETRA 2013 p.2 (“more than 2 % in volume”); JSCE SSCS-2007 p.299 (“approximately 2 %”, L 10–20 mm, d 0.1–0.25 mm); 1 vol % = 78.5 kg/m³	practice
Coarse aggregate	None in the classical system — up to 8 mm published, 10 mm permitted	Fehling uses 2/8 mm basalt at 597 kg/m³; AFGC/NF P 18-470 permits D_sup up to 10 mm	practice
Fresh density	2 300–2 500 kg/m³ (2 200–2 800 permitted)	AFGC–SETRA 2013 Annex 9 (2 500 / 2 750 / 2 480 kg/m³); FHWA-HRT-13-060 p.16 (measured 2 400–2 500); AFGC/NF P 18-470	practice
Fibre aspect ratio l/d	≥ 40 (typically 40–80); ≥ 65 recommended	Sika Fibre-Reinforced Concrete Handbook (good performance at l/d 40–80); JSCE SSCS-2007 p.299; Fehling §2.3.5	practice
Fibre balling factor	no numeric limit is published	fib MC2010 §5.6 contains no balling clause and no guidance document gives a citable figure. The documented checks are the l/d and the fibre length against bar spacing (ACI 544.3R-93)	no IS / ACI clause
28-day compressive strength	140–200 MPa on a cylinder (Ø110 × 220 mm); 100 mm cubes run about 10 % higher	AFGC–SETRA 2013 Annex 9 p.265 (150–200 MPa characteristic, cylinder per NF EN 12390-3); FHWA-HRT-13-060 Table 9 (140–200); JSCE SSCS-2007 p.299 (characteristic ≥ 150 N/mm²)	practice
Autogenous shrinkage	400–900 microstrain	AFGC–SETRA 2013 Annex 7 (Loukili) p.247–248: ε_re(&8734;) = 525 µε; 250 µε at w/b 0.09, 350 µε at w/b 0.15; Annex 9 p.265 (550 µε)	practice
Drying shrinkage	200–600 microstrain	Kassel 2004 p.334 (“similar to HPC but reduced”); negligible after heat treatment	practice
Total shrinkage	550–900 microstrain	AFGC–SETRA 2013 Annex 9 p.265 (600–800 µ/m); FHWA-HRT-13-060 p.24 (600–900 µε at 28 d, 700 at 7 d sealed); Ductal 600–800 µ/m	practice
Secant modulus	40–60 GPa	AFGC–SETRA 2013 Annex 9 p.265 (45–55, 65, 44 GPa); FHWA-HRT-13-060 Table 9 (40–70 GPa)	practice
Electrical resistivity	no published value for steel-fibre UHPC	AASHTO TP 119-21 (FHWA-HRT-21-095) sets a 150 kΩ·cm threshold at 28 d and reports a 215 kΩ·cm minimum — but for NON-metallic-fibre UHPC. Steel fibres depress the resistivity, so the figure is not a valid yardstick for a steel-fibre mix	no IS / ACI clause
Chloride diffusion	1 × 10⁻¹³ m²/s (indicative); 2 × 10⁻¹⁴ m²/s measured in service	AFGC–SETRA 2013 Table 3.3 p.154; measured after 5 years' marine exposure, Tanaka et al. 2010	practice
Equivalent flexural strength	7–10 MPa (f_ctfm at w = 0.3 mm); residual strength class per fib MC2010 §5.6.3	AFGC–SETRA 2013 Annex 9; the test is EN 14651 (notched beam), and MC2010 §5.6.3 requires f_R1k/f_Lk > 0.4 and f_R3k/f_R1k > 0.5. No authoritative compressive-to-flexural relation is published, so none is offered	practice

The full proportioning engine — absolute volume with the total-water w/b convention, live particle packing, and mix-based predictions of strength, flexural strength, shrinkage, creep and heat of hydration — is available in the ConcreteInfo UHPC mix calculator. It is a working tool, not a published design.

IS 16700:2023, Annex C, C-1 — the Indian standard that comes closest to a UHPC specification

IS 16700:2023 is Criteria for Structural Safety of Tall Concrete Buildings (First Revision) — RC buildings 50 m to 250 m in height. It is not an exposure or durability standard, and quoting it as one is a common error. But its Annex C, C-1 sets a concrete specification for tall buildings that speaks directly to a high-strength, silica-fume, mass-concrete system — and it is the only Indian standard that does.

Requirement (Annex C, C-1)	Value
Minimum grade of concrete	M30; grades M45 to M70 “shall be used, wherever essential”
Minimum crushing strain in compression	0.0020
Grade definition	Specified on the 28-day strength; 56-day or 90-day strength may be specified instead
Binder system	OPC with silica fume, ultrafine GGBS or ultrafine fly ash permitted, provided the replacement limits of the relevant codes are not exceeded
Admixtures	To IS 9103; SCM–admixture compatibility to be resolved by laboratory trial
Quality plan	Detailed QA/QC plan from the ready-mix producer; plant certified to IS 4926
Mass concrete — peak temperature	≤ 70 °C, with mock trials and temperature sensors
Mass concrete — thermal gradient	≤ 20 °C
Rapid chloride permeability (RCPT)	Foundations ≤ 1 000 coulombs; superstructure ≤ 1 500 coulombs
Water penetration test	Foundations 15 mm max; superstructure 20 mm max
Total shrinkage strain	≤ 0.04 %, with a guard against autogenous shrinkage at low w/cm (below 0.3)
Polypropylene fibre for fire spalling	0.1 % to 0.15 % by volume, with 135° bent ties at 0.75 × the normal spacing
Curing	To begin immediately after finishing, minimum 10 days; water curing preferred for low w/cm

IS 16700:2023, Annex C, C-1 (Cl. 5.7.1.2), pp. 28–29. The thermal and shrinkage limits are the ones that bite on a UHPC system: a 70 °C peak and a 20 °C gradient are demanding for a mix that generates the heat a binder-rich UHPC does, and the 0.04 % shrinkage limit is a genuine constraint on a low w/cm, silica-fume matrix. The ConcreteInfo UHPC mix calculator checks the current mix against these limits directly.

Reading a chloride test result

ASTM C1202 is the standard rapid chloride permeability test, and it is a conductivity test rather than a diffusion test. The classification below is from the standard itself.

Charge passed, coulombs	Chloride ion penetrability
less than 100	Negligible
100 to 1 000	Very low
1 000 to 2 000	Low
2 000 to 4 000	Moderate
more than 4 000	High

ASTM C1202-08 Table 1. Two cautions that matter on a modern mix. The test applies a voltage to the specimen, so the result is a function of the specimen's electrical resistance; and ASTM C1202 §5.1 and Note 1 warn that admixtures can shift the reading — calcium nitrite is named explicitly, and the note adds that other admixtures might affect results of this test similarly. Where chloride ingress has to be defended, run a diffusion test (RCM / NT Build 357) alongside the RCPT and report both.

Sources, and how to read this guide

The badges on each table distinguish the two things that get confused most often in concrete specification:

code — a value transcribed from a BIS publication held in the standards library. The clause and table are cited.
pract — a working range this practice uses, based on the codes and on trial experience. It is guidance, not a requirement.
no IS / ACI clause — the parameter is not covered by any Indian Standard or ACI document, and the value comes from the UHPC-specific international guidance.

Primary sources used for this guide: IS 269:2015 (Sixth Revision) — cement; IS 456:2000 with Amendment 5 — workability, exposure conditions, durability requirements, cement content; IS 383:2016 — aggregate grading; IS 10262:2019 — mix proportioning; IS 9103 — admixtures; IS 1489 (Part 1) and IS 455 — blended cements; IS 1199 — fresh concrete tests; ASTM C1202 — chloride ion penetrability; ACI 544.3R and 544.4R — steel fibre content, balling and flexural strength; IS 4926 and IS 3812 (fly ash) · IS 16714 and IS 712 (GGBS) · IS 15388 (silica fume) · IS 16354 (metakaolin) — supplementary cementitious materials; IS 16700:2023 Annex C, C-1 — concrete specification for tall buildings; fib Model Code 2010 (fib Bulletin 65) §5.6 and fib Task Group 8.6 — UHPFRC residual strength and non-brittleness; AFGC–SETRA UHPFRC Recommendations (2013); JSCE (2006, published as SSCS-2007); FHWA-HRT-13-060 / 18-036 / 21-095 — US practice and measurements.

Indian Standards are the property of the Bureau of Indian Standards and are shared here as technical reference. Always verify against the official publication before issuing a specification.

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Code references & rights: Indian Standards are the property of the Bureau of Indian Standards (© BIS) — official PDFs at bis.gov.in. Shared in good faith as technical reference for the civil engineering fraternity — always verify against the official publication.