IS-10262-2009-CONCRETE MIX DESIGN – INDIAN STANDARD METHOD

在将混凝土混合物比例为Per-10262-2009之前，应记住以下几点。

• 这种混凝土配合比的方法是应用cable only for ordinary and standard concrete grades.
• The air content in concrete is considered as nil.
• The proportioning is carried out to achieve specified characteristic compressive strength at specified age, workability of fresh concrete and durability requirements.

This method of concrete mix design consist of following 11 steps

1. Design specification
2. Testing of materials
3. Calculating target strength for mix proportioning
4. Selecting water/cement ratio
5. Calculating water content
6. Calculating cement content
7. 找出粗骨料和细骨料的体积比例
8. 混合计算
9. Trial mixing and

10. Workability measurement (using slump cone method)

11. Repeating step 9 & 10 until all requirements is fulfilled.

让我们详细讨论上述所有步骤

步骤1。Design Specifications

This is the step where we gather all the required information for designing a concrete mix from the client. The data required for mix proportioning is as follows.

• 等级称号(无论M10, M15, M20等)
• 要使用的水泥类型
• 最大nominal size of aggregates
• Minimum & maximum cement content
• 最大water-cement ratio
• 可工作性
• 暴露条件（根据IS-456桌-4）
• 最大temperature of concrete at the time of placing
• Method of transporting & placing
• 幼年力量要求（如果有）
• Type of aggregate (angular, sub angular, rounded etc)
• Type of admixture to be used (if any)

第2步。材料测试新利客户

下表显示了在水泥，粗骨料，细骨料和混合物上进行的最必要测试的列表。进行测试后，将测试数据存储以进行进一步计算。

浓缩的rete Ingredients	Tests to be done
Cement	比重	—	—	—
粗骨料	比重	Water absorption	自由表面水分	Sieve analysis
Fine aggregate	比重	Water absorption	自由表面水分	Sieve analysis
混合物 (if any)	比重	—	—	—

第3步。Target Strength Calculation

使用下面给出的公式计算混凝土的目标抗压强度。

f_ck’ = f_ck+ 1.65s

Where,

f_ck’= N/mm 28天时的目标抗压强度².

f_ck= Characteristic compressive strength at 28 days in N/mm². (same as grade of concrete, see table below)

s = Standard deviation

The value of standard deviation, given in the table below, can be taken for initial calculation.

Sl.No	Grade of Concrete	Characteristic compressive strength (N/mm2)	假定的标准偏差（N/mm2)
1.	M10	10	3。5
2。	M15	15
3。	M20	20	4。0
4。	M25	25
5。	M30	30	5。0
6。	M35	35
7。	M40	40
8。	M45	45
9。	M50	50
10.	M55	55

第4步。Selection of Water-Cement Ratio

对于初步计算，可以使用给定的水水泥比为IS-456桌5（也给出以下给定），用于不同的环境暴露条件。

Note:Use表格1for finding out water-cement ratio ofPlain Concrete并使用表2for finding out water-cement ratio ofReinforced Concrete.

Table -1
sl.no。	环境暴露条件	Plain Concrete
		最低水泥含量(公斤/立方米)	最大Free Water-Cement Ratio	混凝土的最低等级
1	Mild	220	0.60	—
2	Moderate	240	0.60	M15
3	Severe	250	0.50	M20
4	Very Severe	260	0.45	M20
5	Extreme	280	0.40	M25

Table -2
sl.no。	环境暴露条件	Reinforced Concrete
		最低水泥含量(公斤/立方米)	最大Free Water-Cement Ratio	混凝土的最低等级
1	Mild	300	0.55	M20
2	Moderate	300	0.50	M25
3	Severe	320	0.45	M30
4	Very Severe	340	0.45	M35
5	Extreme	360	0.40	M40

Refer the table given below (As per IS-456) to choose right type of environment depending upon different exposure conditions to concrete.

Sl.No	Environment	Exposure condition
1	Mild	浓缩的rete surfaces protected against weather or aggressive conditions, except those situated in coastal areas.
2	Moderate	浓缩的rete surfaces sheltered from severe rain or freezing whilst wetConcrete exposed to condensation and rain 混凝土不断在水下 浓缩的rete in contact or buried under non aggressive soil/ground water 浓缩的rete surfaces sheltered from saturated salt air in coastal area
3	Severe	浓缩的rete surfaces exposed to severe rain, alternate wetting and drying or occasional freezing whilst wet or severe condensationConcrete completely immersed in sea water 暴露于沿海环境的混凝土
4	Very severe	浓缩的rete surfaces exposed to sea water spray, corrosive fumes or severe freezing condition whilst wetConcrete in contact with or buried under aggressive sub-soil/ground water
5	Extreme	Surface members in tidal zoneMembers in direct contact with liquid/solid aggressive chemicals

步骤5。Selection of Water Content

Selection of water content depends upon a number of factors such as

• Aggregate size, shape & texture
• 可工作性
• Water cement ratio
• Type of cement and its amount
• Type of admixture and environmental conditions.

Factors that can reduce water demand are as follows

• 使用增加的总尺寸
• Reducing water cement ratio
• Reducing the slump requirement
• 强g rounded aggregate
• 强g water reducing admixture

可以增加水需求的因素如下

• 温度增加。在现场
• Increased cement content
• 衰退增加
• Increased water cement ratio
• 骨料角度增加
• Decrease in proportion of the coarse aggregate to fine aggregate

可以从下面给出的表中选择每单位混凝土的最大混合水的量。

每立方米混凝土的最大水含量，用于标称最大总尺寸
sl.no。	Nominal maximum size of aggregate	最大water content
1	10	208
2	20	186
3	40	165

The values given in the table shown above is applicable only for angular coarse aggregate and for a slump value in between 25 to 50mm.

Do the following adjustments if the material used differs from the specified condition.

Type of material/condition	Adjustment required
对于亚角骨料	Reduce the selected value by 10kg
For gravel with crushed stone	Reduce the selected value by 20kg
For rounded gravel	Reduce the selected value by 25kg
每增加25毫米低迷	将选定的值增加3％
如果使用增塑剂	将所选值降低5-10％
If using super plasticizer	将所选值降低20-30％

Note:Aggregates should be used in saturated surface dry condition. While computing the requirement of mixing water, allowance shall be made for the free surface moisture contributed by the fine and coarse aggregates. On the other hand, if the aggregate are completely dry, the amount of mixing water should be increased by an amount equal to moisture likely to be absorbed by the aggregate

第6步。计算水泥材料内容

From the water cement ratio and the quantity of water per unit volume of cement, calculate the amount of cementious material. After calculating the quantity of cementious material, compare it with the values given in the table shown in Step-4. The greater of the two values is then adopted.

If any mineral admixture (such as fly ash) is to be used, then decide the percentage of mineral admixture to be used based on project requirement and quality of material.

第7步。找出粗骨料和细骨料的体积比例

在下表中给出了对应于不同区域的不同区域的总骨料单位体积的粗骨料的体积。

sl.no。	Nominal 最大 大小 Aggregate (mm)	Volume of coarse aggregate per unit volume of total aggregate for different zones of fine aggregate
		第四区	第三区	区I	区
1	10	0.50	0.48	0.46	0.44
2	20	0.66	0.64	0.62	0.60
3	40	0.75	0.73	0.71	0.69

The values given in the table shown above is applicable only for a water-cement ratio of 0.5 and based on aggregates in saturated surface dry condition.

If water-cement ratio other than 0.5 is to be used then apply correction using the rule given below.

规则:For everyincrease or decreaseby0.05inwater-cement ratio, theabove values将会减少或增加by0.01,respectively.

If the placement of concrete is done by a pump or where is required to be worked around congested reinforcing steel, it may be desirable to reduce the estimated coarse aggregate content determined as above, upto 10 percent.

计算出粗骨料的体积后，从1中减去，以找出细骨料的体积。

第8步。Mix Calculations

The mix calculations per unit volume of concrete shall be done as follows.

a	Volume of concrete=	1m3
b	水泥的体积=	(Mass of cement/specific gravity of cement)*(1/1000)
c	水量=	(Mass of water/specific gravity of water)*(1/1000)
d	Volume of admixture=	(Mass of admixture/specific gravity of admixture)*(1/1000)
e	Volume of total aggregate (C.A+F.A)=	[a-(b+c+d)]
f	质量粗骨料=	E*粗骨料的体积*粗骨料的比重*1000
g	Mass of fine aggregate=	e*Volume of fine aggregate*specific gravity of fine aggregate*1000

Step-9.Trial Mix

Conduct a trial mix as per the amount of material calculated above.

步骤10。Measurement of Workability (by slump cone method)

The workability of the trial mix no.1 shall be measured. The mix shall be carefully observed for freedom from segregation and bleeding and its finishing properties.

步骤11。Repeating Trial Mixes

If the measured workability of trial mix no.1 is different from stipulated value, the water and/or admixture content shall be adjusted suitably. With this adjustment, the mix proportion shall be recalculated keeping the free water-cement ratio at pre-selected value.

试验2– increase water or admixture, keeping water-cement ratio constant

试验3- 保持与试验2相同的水含量，但将水泥浆比增加10％。

试验4– Keep water content same as trial-2, but decrease water-cement ratio by 10%

Trial mix no 2 to 4 normally provides sufficient information, including the relationship between compressive strength and water-cement ratio.