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Concrete Mix Design by DOE Method

In this article, We're going to create Concrete Mix Design by DOE Method with a concrete mix design example for a better explanation for making this concrete mix design calculation easy to understand so read the whole article & download concrete mix design doe method pdf

Concrete Mix Design by DOE Method

    The DOE method was first introduced (published) in 1975 and then revised in 1988.

    While Grading Curve Method was specifically developed for concrete pavements, the DOE method applies to concrete for most purposes, including roads.

    Since the DOE method presently is the standard British method of concrete mix design, the procedure involved in this method is described instead of the outdated Road Note No 4 method.

    Step 1: Required Data to be Collected

    • Fineness modulus of selected F.A.
    • Unit weight of dry rodded coarse aggregate.
    • Sp. gravity of coarse and fine aggregates in SSD condition
    • Absorption characteristics of both coarse and fine aggregates.
    • Specific gravity of cement.

    Let me take a concrete mix design example for data to make it easy to understand

    1. Grade Designation = M 30
      • For which we have to design concrete mix to achieve this particular strength of concrete for construction work of the project
    2. Type of cement = O.P.C- 43 grade
      • More than 17 different types of cement available for special construction work and every condition demand different material to more suitable, economical and durable structure.
    3. Fine Aggregate = Zone-II
    4. Sp. Gravity Cement = 3.15
    5. Fine Aggregate = 2.61
    6. Coarse Aggregate (20mm) = 2.65
    7. Coarse Aggregate (10mm) = 2.66

    Step 2: Target Mean Strength

    Find the target mean strength from the specified characteristic strength (Grade Designation) 

    Target mean strength = specified characteristic strength + (Standard deviation x risk factor)

    Where risk factor is on the assumption that 5 percent of results are allowed to fall less than the specified characteristic strength.

    π‘“π‘š=30+(1.65 π‘₯ 5.0)

    π‘“π‘š=38.25 π‘€π‘ƒπ‘Ž

    Step 3: Water/cement ratio

    Calculate the water/cement ratio. This is done in a rather round about method, using Table 11.11

    WC ratio as per british method

    Referring to Table 11.11, for OPC, uncrushed aggregate, for W/C ratio of 0.5, 28 days compressive strength is 49 MPa.

    Concrete Mix Design by DOE Method

    In above Fig. find an intersection point for 42 MPa and 0.5 W/C ratio. Draw a dotted line curve parallel to the neighbouring curve. From this curve read off the W/C ratio for a target mean strength of 39 MPa.

    The Water/cement ratio is = 0.58 

    Check this W/C ratio from durability consideration from Table 9.20. The maximum W/C ratio permitted is 0.50. Adopt lower of the two Therefore adopt a W/C ratio of 0.50

    Concrete Mix Design by DOE Method

    Step 4: Calculation of Water Content

    • Next decide the water content for the slump of 75 mm (assumed) 20 mm uncrushed aggregate from Table 11.12.
    • In the case of CA & FA are different
    • Water demand for natural fine aggregate = 195 lit
    • Water demand for crushed coarse 20mm max size aggregate = 225 lit

    π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ = [(2/3)×W𝑓]+[(1/3)×Wπ‘π‘Ž]

    π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ = [2/3×195]+[1/3×225]

    π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ = 205.0 π‘˜π‘”π‘š3

    Table 11.12: Approximate Free Water Contents Required to Give Various Levels of Workability According to the 1988 British method

    Concrete Mix Design by DOE Method

    Step 5: Calculating Cement Content

    Mixing water content is 205 kg/m3 of concrete.

    πΆπ‘’π‘šπ‘’π‘›π‘‘ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ = 205/0.50

    πΆπ‘’π‘šπ‘’π‘›π‘‘ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘=410.0 π‘˜π‘”π‘š3

    Which is more than 350 kg (As per Table No. 9.2 of BS 8110: Part I: 1985) Hence o.k.

    Also Read: What is the use of chicken wire mesh in construction Civil Experience

    Step 6: Calculating Weight of Total Aggregate

    • This requires an estimate of the wet density of the fully compacted concrete. This can be found out in Fig. 11.4 for approximate water content and specific gravity of aggregate.

    • Next, find out the density of fresh concrete from Fig. 11.4 for the water content of 205 kg/m3, 20 mm uncrushed aggregate of sp.gr. 2.65

    The wet density = 2375.0 kgm3

    Concrete Mix Design by DOE Method  | Calculating Weight of Total Aggregate

    Total Weight of aggregate is find out

    Weight of Total Aggregate = The wet density - (Weight of Cement + Weight of Free Water)

    Weight of Total Aggregate = 2375 - (410 + 205)

    Weight of Total Aggregate = 1760 kg/m3

    Step 7: Calculating Weight of Fine Aggregate

    Then, the proportion of fine aggregate is determined in the total aggregate using below Fig. Fig. (a) is for 10 mm size, (b) is for 20 mm size and Fig. (c) is for 40 mm size coarse aggregate.

    Calculating Weight of Fine Aggregate | Concrete Mix Design by DOE Method

    The parameters involved are the maximum size of coarse aggregate, the level of workability, the water/cement ratio, and the percentage of fine spassing 600 ΞΌ seive.

    For 20 mm aggregate size, W/C ratio of 0.50, Slump of 75 mm, for 50% fines passing through 600 ΞΌ sieve, the percentage of

    % 𝐹𝑖𝑛𝑒 π΄π‘”π‘”π‘Ÿπ‘’π‘”π‘Žπ‘‘π‘’ = 41 %

    Weight of F.A. = 1760 × (41/100)

    Weight of F.A. = 721.6 kg/m3

    and

    Weight of C.A. = 1760 × (59/100)

    Weight of C.A. = 1038.4 kg/m3

    Step 8: Combination of Different Coarse Aggregate Fractions

    Course aggregate can be further divided into different fractions depending on the shape of aggregate. As general guidance the figures given in Table 11.14 can be used.

    Also Read: How to Design of Two Way Slab by EXCEL Sheet

    Step 9: Proportions for Concrete Mix Design

    Ingredients

    Quantity kg/m3

    Ratio

    1 Bag Cement

    Cement

    410

    1

    50

    Fine Aggregate

    721.6

    1.76

    88

    Coarse Aggregate

    1038.4

    2.54

    127.0

    Water

    205

    0.50

    25

    Chemical

    NM

    NM

    NM

    Step 10: Adjustment for Field Condition

    The proportions are required to be adjusted for the field conditions. Fine Aggregate has surface moisture of 2 %

    Weight of F.A. = 721.6 + (2/100) 721.6

    Weight of F.A. = 736.03 kg/m3

    Course Aggregate absorbs 1% water

    Weight of C.A. = 1038.4 - (1/100) 1038.4

    Weight of C.A. = 1028 kg/m3

    Step 11: Final Design Proportions

    Ingredients

    Quantity kg/m3

    Ratio

    1 Bag Cement

    Cement

    410

    1

    50

    Fine Aggregate

    728

    1.80

    90.0

    Coarse Aggregate

    1029.1

    2.51

    125.5

    Water

    205

    0.50

    25.0

    Chemical

    NM

    NM

    NM

    Also ReadConcrete Mix Design as per IS CODE easy way by excel sheet

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