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监理 - 2009/6/27 15:22:00
(一)基本要求:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.拌制成的混凝土要有良好的合易性;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.满足强度要求;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
3.混凝土要有良好的耐久性;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
4.施工上经济合理。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(二)基本参数(已知条件)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.混凝土设计强度的等级;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.混凝土拌合料的坍落度;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
3.水泥品种、等级强度、质量水平;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
4.粗、细集料品种(最大粒径、砂的细度模数、级配范围等);u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
5.外加剂,掺合料品种质量;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
6.对混凝土的特殊要求(如抗冻、抗渗等要求).u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(三)设计步骤:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.计算配合比:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(1)混凝土配制强度的确定:按公式fcu,0≥fcu,k+1.645Óu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
其中fcu,0——混凝土配制强度(Mpa);u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fcu,k ——混凝土立方体抗压强度标准值(Mpa)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
Ó——混凝土强度标准差(Mpa)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
当无统计资料时,查下表Ó值(N/mm2)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

混凝土强度u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

<C20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

C20- C35u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

> C35u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

Óu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

4.0u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

5.0u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

6.0u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

(2)求水灰比(<C60等级以下时)按下面公式计算:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
W/C=αa u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fce÷fcu,0+αaαb fceu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
①其中αaαb——回归系数,当无统计资料时,查下表:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

碎石u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

卵石u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

αau¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.46u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.48u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

αbu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.07u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.33u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

②fce——水泥28天强度实测值(Mpa),当无水泥28天强度实测值时,可按公式确定:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fce=γc 。fce,g ;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
公式中γc——水泥强度等级值的富余系数,一般取1.13,也可按实际统计资料确定;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fce,gu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
— 一般取水泥强度等级值(Mpa);也可按3天强度值或快测强度推定28天强度关系式推定得出。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(3)用水量u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
①当水灰比在0.4-0.8之间查下表:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
干硬性混凝土的用水量(kg/m3)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

拌合物稠度u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

卵石最大粒径mmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

碎石最大粒径mmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

项目u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

指标u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

10u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

16u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

维勃u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

稠度u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

(s)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

16-20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

175u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

160u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

145u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

180u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

170u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

155u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

11-15u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

180u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

165u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

150u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

185u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

175u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

160u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

5-10u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

185u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

170u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

155u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

190u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

180u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

165u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
注:a、本表用水量系采用中砂的平均值。采用细砂时每立方米混凝土用水量增加5-10kg; 采用粗砂时每立方米混凝土用水量减少5-10kg;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
b、掺用各种外加剂或掺合料时,用水量应相应调整。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
②水灰比小于0.4的混凝土以及采用特殊成型工艺的混凝土用水量应通过试验确定。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
流动性和大流动性的用水量宜按下列步骤计算:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

塑性混凝土的用水量(kg/m3)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

A.以坍落度90mm的用水量为基础,按坍落度20mm用水量增加5kg。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
B.实际水量mwo=y+[(x-90)÷20]×5u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
( x为已知坍落度u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
y为增加水量)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(碎石mm-y=16mm-230、20mm-215、31.5mm-205、40mm-195) ;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(卵石mm-y=10mm-215、20mm-195、31.5mm-185、40mm-175) u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
C.掺外加剂时的混凝土的用水量可按下式计算:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mwa = mwo(1-β)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mwa -----掺外加混凝每立方米混凝土的用水量(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mwo------未掺外加混凝每立方米混凝土的用水量(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
β---外加剂的减水率(%)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(4)水泥用量:mco=mwo/(w/c)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(5)砂率u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
无历史统计资料可参考时,混凝土砂率确定应符合下列规定:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
①坍落度为10-60mm的混凝土砂率,可查下表:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

混凝土的砂率(%)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

水灰比u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

(W/C)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

卵石最大粒径mmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

碎石最大粒径mmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

10u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

16u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

26-32u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

25-31u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

24-30u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

30-35u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

29-34u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

27-32u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.50u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

30-35u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

29-34u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

28-33u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

33-38u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

32-37u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

30-35u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.60u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

33-38u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

32-37u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

31-36u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

36-41u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

35-40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

33-38u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0.70u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

36-41u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

35-40u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

34-39u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

39-44u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

38-43u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

36-41u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

注:此表为中砂的选用砂率(砂与骨料总量的重量比),细砂减少、粗砂增加。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
只用一个单粒级粗骨料配制混凝土使,砂率增大。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
对簿壁构件,砂率取偏大值。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
②坍落度大于60mm的混凝土砂率,坍落度增大20mm,砂率增大1%的调整,u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
③坍落度小于10mm的混凝土按经验确定。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
混凝土浇筑入模时的坍落度表u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

结构类别u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

坍落度(mm)(振动器振动)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

小预制块及便于浇筑振动的结构u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

0-20u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

桥涵基础、墩台等无筋或少筋的结构u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

10-30u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

普通配筋率的钢筋混凝土结构u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

30-50u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

配筋较密、断面较小的钢筋混凝土结构u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

50-70u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

配筋较密、断面高而窄的钢筋混凝土结构u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

70-90u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%

5.每立方米混凝土的水泥用量(mc0)。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
按公式计算:mc0= mw0/(w/c)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
6.粗、细骨料用量的确定,建议采用重量法。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
按下式计算:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mc0+ mg0+ ms0+ mw0= mcpu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(mcp=2350-2450kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
.…..(1)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
βs= ms0/(mg0+ ms0)×100%u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
……(2) u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
注:mc0—水泥 、 mg0—粗骨料、 ms0—细骨料、mw0—用水量、βs—砂率(%)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
由(1)、(2)解出各值。必须依据下表,检查混凝土的最大水灰比和最小水泥用量。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(四)混凝土配合比的试配:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.采用工程中实际使用的原材料,搅拌方法与实际生产相同。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.每罐砼的最小搅拌量为15L(或25L)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
3.试件,检查拌合物和易性,调整用水量、砂率,提供混凝土强度试验用基准配合比。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
4.采用三个不同水灰比作强度试件,其中一个基准配合比,另外两个配合比的水灰比,宜较基准配合比分别增加和减少0.05,用水量应与基准配合比相同,砂率分别增加和减少1%。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
5.相应检验混凝土的坍落度(维勃稠度)粘聚性、保水性、表观密度。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
6.进行试验时,每种配合比试块的数量不少应作一组(三块)。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(五)混凝土配合比的调整与确定u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.绘制水灰比曲线,注意直线不得外延,选定C/W≥C/W’u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.确定每立方米材料用量:mw/mc/ms/mg (kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
3.材料用量校正u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(1)计算表观密度PC,C= mw+mc+ms+mgu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(2)计算砼配合比校正系数δu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
δ=PC,T/PC,C(PC,T—实测值PC,C—计算值)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(3)PC,T与PC,C之差绝对值≤PC,C的2%时,配合比调整后的材料用量即为设计值配合比( PC,T-PC,C)/ PC,C≤2%;如超过2%,可得到的每项材料均乘以校正系数后确定为设计配合比。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(六)施工配合比调整:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
调整砂质量,要求不含水,提出每盘料所需材料用量。遇以下情况之一者,应重新进行配合比设计:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.对混凝土性能指标有特殊要求时;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.水泥、外加剂或矿物掺合料品种、质量有显著变化时;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
3.该配合比的混凝土生产间断半年以上时。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(七)混凝土配合比设计例题:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
已知:原材料42.5Mpa强度等级的普通规酸盐水泥,其富余系数为1.1,中砂,卵石、Dmax=20,外加剂掺量占水泥的1.5%,减水率20%,要求配制T=190mm(坍落度)C30普通砼,无统计标准值。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
解:(1)求配制强度u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fcu,0≥ fcu,k+1.645δ (选δ=5.0)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fcu,0≥30+1.645x5.0≥38.2Mpau¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fcu,0=39.0 Mpau¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(2)求水灰比u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
W/C=αa u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fce÷fcu,0+αaαb fceu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
fce=γc 。fce,g ;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
w/c=(0.48x1.1x42.5)/(39.0+0.48x0.33x1.1x42.5)=0.48u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
当γc=1.0则W/C=0.45u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(3)用水量,查表u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mw0=195+[(190-90)/20]x5=220(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
由于加入外加剂,mwa = mwo(1-β)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mwa=220x(1-20%)=176(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(4)水泥用量mco=mwo/(w/c)=176/0.48=367(kg/m3)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(5)砂率:βs=30+(190-60)/20x1%=36.5%u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
选βs=37%u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(6)计算砂、石量u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
假定砼干表观密度mcp=2400u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mc0+ mg0+ ms0+ mw0= mcpu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(1) βs= ms0/(mg0+ ms0)×100%u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(2) 解:mg0=1170(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
ms0=687(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(7)外加剂量u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
ma0= mc0x1.5%=367x1.5%=5.5(kg)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
经试拌,如强度符合设计要求,该计算配合比即为基准配合比,选取w/c以及w/c±0.05三个配合比作强度试件,测表观密度,耐久性。若28d强度正是所要求得配制强度,则需进行制成量校正。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
该实测表观密度为2320 kg/m3 PC,tu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
∣( PC,t-PC,C)/ PC,C∣=(2400-2320)/2400=3.3%>2%u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
需调整:δ校正系数= PC,t/ PC,C=2320/2400=0.97u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
配合比为:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mc0=367x0.97=356kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mg0=176x0.97=171kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
ms0=687x0.97=666kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mw0=1170x0.97=1135kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
ma=5.5x0.97=5.34kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
施工配合比计算:如砂含水量3%,石含水1%;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
ms`= ms(1+0.03)=686kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mg`= mg(1+0.01)=1146kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mw`=171-(686-666)-(1146-1135)=140kg/m3u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
施工配合比:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
每立方米混凝土材料用量为:水泥356kg、水140 kg、砂686kg、石1146kg、外加剂5.34kgu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
水泥:砂:石:水=1:1.93:3.22:0.39u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
二、沥青混凝土配合比设计u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(一)基本要求:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.选择合格的材料u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.确定各种粒径矿料和沥青的配比u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(二)矿料的最大粒径:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.沥青砼中的最大粒径D同路面结构最小厚度h的关系有规定:D=0.5hu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
h/D 比值越大,疲劳耐久性提高,车辙量增大u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.国产沥青混合料 u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
D=30-35mm粗粒式砼中h=4-7cm; u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
D=20-25mm中粒式砼中h=4-5cmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
D=15mm细粒式砼中h=3cmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
D=35-40mm沥青碎石中h=7-8cmu¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(三)矿料配合比设计u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1.确定矿料筛分级配曲线:级配取线可采用下表所列级配中值。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(1)对粗集料、细集料、填料进行筛分,得出各种矿料的筛分曲线。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(2)测定粗集料、填料及沥青的相对密度(25/25℃)。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
2.计算各种矿料的配合比:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(1)由各种矿料的筛分曲线计算矿料的配合比,使合成的混合料矿料级配符合表一的级配范围。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(2)矿料的配合可用计算机进行试配,直至满足规定级配要求。或用图解法确定各组成矿料的配合比。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
3.确定沥青最佳用量u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(1)根据经验或表以所列的沥青用量范围估计一个沥青用量(或油石比)。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(2)以估计的沥青用量为中值,按1.5%间隔变化取5个不同的油石比(或按0.5%变化沥青用量),制备马歇尔试件。按规定测定试件的密度,并计算空隙率、沥青饱和度、矿料间隙率等物理指标。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(3)进行马歇尔试验,测定沥青混合料马歇尔稳定度、流值。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(4)以沥青用量为横坐标,各项测定指标为纵坐标,分别绘制:密度—沥青用量;空隙率—沥青用量;沥青饱和度—沥青用量;稳定度—沥青用量;流值—沥青用量相关图。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(5)从图中求取相应于密度最大值的沥青用量a1,相应于稳定度最大值的沥青用量a2,及相应于规定空隙率范围中值的沥青用量a3,求取三者的平均值作为沥青用量得初始值。OAC1=(a1+a2+a3)/3。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(6)由沥青混合料马歇尔试验技术标准的沥青用量范围的OACmin最小值和OACmax最大值,求取二者平均值为OAC2。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
(7)由OAC1和OAC2综合决定最佳用量,要求根据实践经验和公路等级、气候条件按下列步骤进行:u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
a.一般可取二者的中值为最佳用量;u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
b.对热区公路,预计用较大车辙情况时,可在OAC2与下限OACmin范围内决定,但不宜小于OAC2的0.5%。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
对寒区公路,最佳沥青用量可在OAC2与上限OACmax范围内决定,但不宜大于OAC2的0.3%。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
185866494 - 2009/6/28 10:03:00
不错,,学习学习u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
liyineng117 - 2009/9/3 12:04:00
我是个初学者,想问一下关于普通混凝土配合比设计步骤中外加剂的问题。u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
例如:计算用水量:  mw0按经验选取205(kg/m3) 掺高效减水剂0.8%,减水率25%,则u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
mw0=205×(1-25%)=154 (kg/m3)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
        计算减水剂用量:mj=497(水泥用量)×0.8%=3.976(kg/m3)u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
如果外加剂为液体外加剂时,其含一定的水量,那要不要从计算的用水量154kg减去液体外加剂的含水量呢?u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
如果可能是因为外加剂的量比较小,其含水量可不做考虑,那不做考虑的量的限度是多少呢?u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
如果是粉末外加剂的时,其用的质量是从骨料的质量中减去吗?u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
wentyoulove321 - 2016/2/3 13:53:49
不错u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
wentyoulove321 - 2016/2/3 21:57:27
加油u¼Æˆ;ï/ޕåbbs.3c3t.comã$¶ /o(¾H%
1
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