用于可加工测量的不同测试方法

Depending upon the water cement ratio in the concrete mix, the workability may be determined by the following three methods.

1. Slump Test
2. Compaction Factor Test
3. VEE-BEE VELOURAPER TEST

1。Slump Test

Suitability

该方法仅适用于高可加工性的混凝土。

该试验与称为坍落度锥体的模具进行，其顶部直径为10cm，底部直径为20cm，高度为30厘米。

程序

The test is performed in the following steps:

1. 将坍落度模具放在光滑的平坦和非吸收性表面上。
2. 将混凝土的干成分彻底混合，直至获得均匀的颜色，然后加入其中所需的水量。
3. Place the mixed concrete in the mould to about one-fourth of its height.
4. Compact the concrete 25 times with the help of a tamping rod uniformly all over the area.
5. 将混合混凝土放入模具中至约一半的高度并再次紧凑。新利18体育官网登录
6. 同样地，将混凝土置于其四分之三的高度，然后将其放置在其顶部。在夯实杆均匀的帮助下压实每层25次。对于第二和随后的层，夯实杆应渗透到下层。
7. 用抹子或夯杆撞击模具的顶部表面，使模具填充到其顶部。
8. 立即取下模具，确保其在垂直方向上的运动。
9. 当混凝土停止时，测量混凝土的沉降，以毫米为例slumpof the concrete.

各种混凝土工程的推荐坍落度值

建筑类型	Recommend slump in mm
	Minimum	Maximum
铺路	25.	50.
Mass concrete structure	25.	50.
Unreinforced footings	25.	75.
Caissons and bridge decks	25.	75.
加强基础，基础和墙壁	50.	100
加强板和梁	30.	125.
列	75.	125.

坍落试验的局限性

以下是限制

• 不适用于含有大于40mm的聚集体的混凝土。
• Not suitable for concrete of dry mix.
• Not suitable for very wet concrete.
• 不可靠，因为坍落度可能是任何形状。

2。Compaction Factor Test

According to this test, the workability may be defined as the amount of applied work required to compact the concrete to its maximum density.

Suitability

This method is adopted for determining the workability of concrete mix in laboratories. It gives fairly good results for concrete of low workability.

程序

执行压实因子测试所需的装置如下所示。

1. The test is performed in the following steps:
2. Clean and dry the internal surface of the mould.
3. With the help of hand scoop, place the concrete in upper hopper A.
4. Open the trap door of hopper in order to facilitate the falling of the concrete into lower hopper B. the concrete sticking to the sides of the hopper A, should be pushed downward with the help of a steel rod.
5. Open the trap door of the hopper B and allow the concrete to fall into cylinder C.
6. Remove the surplus concrete from the top of the cylinder with the help of a trowel. Wipe and clean the outside surface of the cylinder.
7. 用最靠近10g的部分压实混凝土称量气缸。
8. Fill in the cylinder with fresh concrete in layers not exceeding 5 cm in thickness and compact each layer till 100 percent compaction is achievd.
9. 擦去并清洁气缸的外表面，称重最靠近10克的完全压实混凝土的气缸。
10. 使用以下公式计算压实因子的值。

压实因子=完全压实混凝土部分压实混凝土/重量的重量

推荐的各种放置条件的可操作性值

Conditions	Degree	可加工性的值
Concreting of shallow sections with vibrations	非常低	20 – 10 seconds Vee-Bee time or 0.75 to 0.80 compacting factor
Concreting of lightly reinforced sections with vibrations	Low	10 - 5秒的vee-bee时间或 0.。80 to 0.85 compacting factor
轻微加固段的混凝土，无振动或具有振动的巨大增强部分	中等的	5-2秒vee-bee时间或 0.85至0.92压实因子或 25.-75.mm slumps for 20 mm aggregates
Concreting of heavily reinforced sections without vibrations	High	Above 0.92 compacting factor or 75 – 125 mm slump for 20 mm aggregates.

Advantages of Compaction Factor Test

以下是优势：

• Suitable for testing workability in laboratories
• 适用于低可加工性的混凝土
• Suitable to detect the variation in workability over a wide range
• 其结果更加精确和敏感。

3.VEE-BEE VELOURAPER TEST

The apparatus used in this method of test is shown below.

Suitability

该方法适用于具有非常低的可加工性的干混凝土

程序

测试进行如下所述描述

1. Mix the dry ingredients of the concrete thoroughly till a uniform colour is obtained and then add the required quantity of water.
2. Pour the concrete into the slump cone with the help of the funnel fitted to the stand.
3. 拆下坍落度模具并旋转支架，使透明盘接触混凝土的顶部。
4. 启动放置圆柱形容器的振动器。
5. 由于振动作用，混凝土开始重新铺设并占据圆柱形容器。继续振动圆柱体，直到混凝土表面变得水平。
6. 在几秒钟内完成重复所需的时间是所需的可加工性的衡量标准，并且它表示为Vee-Bee秒的数量。

各种方法的可加工测量比较

Workability Description	猛击mm.	vee-bee时间以秒为单位	压实因子
非常干燥	-	32 - 18
非常僵硬	-	18 - 10	0.。70
僵硬的	0.-25.	10 – 5	0.。75.
僵硬的plastic	25 - 50	5 – 3	0.。85
Plastic	75.-100	3 - 0	0.。90
流动	150 - 175.	-	0.。95