Building Materials, Third Edition

g™

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= 15 +




1.65

1.65 – 3.5

11

= 15 + 4.03 = 19.03 N/mm^2

Current x =

10 18.74
22.1

11

= 19.05 N/mm^2

> 19.03 N/mm^2

Hence, the concrete is acceptable.

Examples 11.3: Design a concrete mix to be used in structural elements by IS method for
following requirements.

(i) Characteristic compressive strength at 28 days, fck 25N/mm^2

(ii) Maximum size of the available aggregate 20 mm

(iii) Shape of coarse aggregate angular

(iv) Degree of workability desired, compacting factor 0.85

(v) Degree of quality control good

(vi) Type of exposure moderate

Test data for concrete making materials

Specific gravity of cement 3.15

Specific gravity of coarse aggregate 2.72

Specific gravity of fine aggregate 2.66

Water absorption (air dry to saturated surface dry)

in coarse aggregate, per cent 0.5

Surface moisture

coarse aggregate nil

Fine aggregate, per cent 2

(vi) Compressive strength of cement at 28 days, 51 N/mm^2

Sieve analysis

s ƒg



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h  — —     

p—™

2s p—™

2ss

IH2-- PH2--

RH2-- IHH IHH

PS2-- IHH IHH

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IPS2-- IHH PR

IH2-- WH IP IHH

RUS R I WP

PQT2-- Q ' VT

IIV2-- ' ' UV

THHE-

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QHHE-

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ISHE-

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