MEASURING BOX USED IN SITE

MEASURING BOX USED IN SITE




In volumetric batching of concrete, the ingredients of concrete are measured by their volume before they are mixed for making the durable concrete. The concrete ingredients are measured in measurement boxes of standard size. The measurement boxes are also known as “Farmas” or “Gauge Boxes”.Workers use troughs for the measurement of concrete ingredients on site. But, it is not a proper way to measure the quantity of concrete ingredients for making designed concrete. To ensure the uniformity of proportions and aggregate grading in succeeding batches, the proper and accurate measurement of all the material used in concrete making is necessary.

For volumetric batching, it is convenient to make steel or wooden boxes (farmas) of various sizes/ volumes. In an ideal case, the volume of the farma is made equal to the volume of one bag of cement i.e. 35 liters or multiple thereof. The farmas are made comparatively deeper with the narrow surface rather than shallow with the wider surface to facilitate easy leveling of the top level. The internal dimensions of the boxes shall be generally 35x25x40 cm deep or as otherwise approved by the Engineer-in-charge. Measurement boxes are prepared based on the volume of a cement bag. Hence if you need concrete of proportion 1:2:4, you need 1 Bag of cement, 2 Measurement boxes of sand, 4 measurement boxes of coarse aggregate & 25-liter water (if water-cement ratio is 0.5).

It is advisable to have boxes of various sizes readily available at the site so that any adjustment which is required to be made by way of change in concrete mix design or due to bulkage of sand can be done easily. It is also advisable that during the measurements of aggregates, the measurement boxes which are filled with aggregates should not be shaken, rammed or heaped. 






Comments

Post a Comment

Popular posts from this blog

3 4 5 METHOD USED IN SETTING OUT

Image
3 4 5 METHOD USED IN SETTING OUT The 3 4 5 method is an accurate method use in Ge tting the Exact Square of a Plan instead of Using the Engineering Square which may not be accurate for a Longer Span.   The 3 4 5 method is an application of the Pythagoras Theorem. i.e Forming right Angle. Most times, 2 or 3 people are involved in this.  3 meters is Measure from the Parallel Line created, then 4 Meter Away from the First point forming a Right Angle, you use your Measuring tape to Confirm the distance between the 3m point noted at the parallel line and the 4m noted at the other line is 5m. Note that your Parallel line remains The same, you only shift the other line to form the right Angle.
Read more

HONEYCOMBS IN CONCRETE AND REMEDIES

Image
HONEYCOMBS IN CONCRETE AND REMEDIES Honeycombs  are hollow spaces and cavities left in concrete mass on a surface or inside the concrete mass where concrete could not reach. These look like honey bees nest. When concrete is poured into the formwork it does not just flow in like water and fill up the forms to the top. The concrete has to be vibrated for ease of flow and to form a uniform surface. If it is not vibrated properly it may leave voids exposing the aggregate. The surface on concrete appears as a rough, pitted with voids in concrete resulting incomplete filling with the gap between the aggregates of the concrete against the formwork. Such type of surface and texture on concrete resemblance like a Honeycomb in a beehive of Honey Bee. This scenario can happen on any structural element- Columns, Beams,, Lift Walls, Foundation of any type, etc. Honeycombs which are on sides are visible to naked eyes and can be detected easily as soon shuttering is removed. Honeycombs that are
Read more

Crank Bar in slab

Image
Crank Bar in  slab The slab is supported at two ends. The maximum tensile stress that is positive moments (sagging) acting in the middle of the slab and the maximum compressive stress that is negative moments (hogging) acting at both ends of the support. So bottom steel is required at the mid-span and top steel resists negative moments at the supports. A bent-up bar called a  crank bar  is provided to make RCC slab safe from compressive stresses. So crank bars are generally provided 1. To resist the negative bending moment (hogging). 2. To  resist shear force which is greater at supports. 3. To reduce the risk of brittle failure of slab-column connection. 4. To reduce the amount of steel used. 5. For the economization of materials.
Read more