Do you know how to calculate the needs of workers and materials in the masonry work of retaining walls?

Hello, how are you guys, nice to meet you again. Today I will be writing about how to calculate the need for construction work, so first I will tell you why I created this post.

After a few days ago I finished a design of one of the monuments on the outermost island of Indonesia, so I continued a work of planning for the reinforcement of a cliffs and their implementation, actually this work had taken several days to be completed for one reason or another which finally made me slow down a bit.

Reinforcement of this cliff is very much needed at this time because after the tsunami hit Aceh, some of a main roads could no longer be used, then the government finally made a new road, one of which is in my location and needs special handling because we have to cut a hill to make a new road, but a lower side of a hill is directly opposite an Indian Ocean, as a result, after several years of road construction there has been scouring of a soil from a dug out of a hill, or erosion has occurred. If it is not handled immediately, it is feared that a road that has been built will also be eroded.

Documentation of the cliff to be handled, image by @halukha

Before the construction process, I had to go through several stages, including:

Initial survey
in this initial survey, my team and I analyzed what was needed and the length of treatment needed immediately, we used GPS, pocket cameras, small and large meters as well as information from local residents about a maximum wave height and all an initial data needed to determine a type and how to handling it, we usually collect a data's and analyze it by taking into account various aspects so that we can determine how a building should be built by taking into account a strength, cost-effectiveness and fast completion.

Initial survey using a length meter (50 m), image by @halukha

Early result application
After we processed the data we obtained from an initial survey stage and it was determined a shape of a building to be built, then my team and I then returned to conducting a more detailed survey, at this stage we used survey tools such as theodolite and other tools, at this stage we have determined the Benchmark (BM) point so that it can be used as a reference later when a construction is carried out by a contractor, we have been able to determine the length and height of a cliff retaining building and a costs required.

Detailed measurements using survey tools, image by @halukha / @kharrazi

We started to make wooden stakes and colored them and marked an order of a stakes. We use these data as a reference for the final design of the cliff retaining building.

Carry out construction work

Stone >1000 kg, image by @halukha / @kharrazi

After the construction drawings and bill of quantity are completed, next stage is a construction stage, a materials can be brought to the location because a volume is known.

Heavy equipment and builders can also be mobilized, before excavation or in an early stages of work it is necessary to re-measure and install a bowplank, my team and I ensure that the design results are in accordance with real field conditions, if there are errors, the design will be changed and must immediately follow field conditions.

Re-measurement, image by @halukha

Re-measurement, image by @halukha / @kharrazi

Materials and heavy equipment are already at the job site.

Workers are directing heavy equipment, image by @halukha

And our work ready to be carried out.
In addition to using large stones, we also use river stones to be used as retaining walls for cliffs along with foundations, columns and reinforced concrete beams.

The question is, how do we calculate the labor and material requirements for a retaining walls work?
For example, the volume of stone masonry is 1 m³ then this is the calculation.

We use the analysis of an unit price of work as published by the Ministry of Public Works of the Republic of Indonesia in the field of water resources no. P.01c.1[1] crushed stone with type N mortar (equivalent to 1 portland cement : 4 tide sand).


Workerspeople per day2.700
Masonspeople per day0.900
Foremanpeople per day0.270

Materials needed

Split stone1.200
Tide sand0.520
Portland cementkg163

So with these coefficients, you can determine the need for the number of workers and the amount of material.

The work we are currently doing requires special handling because it needs to be followed up immediately.

The calculation above is an example that can be used according to field needs and the analysis is in accordance with the attachment of the Indonesian government ministry of public works and public housing no. P.01c.1[1] .
This work is still ongoing and currently in the process of forming a cliff using heavy equipment (excavators) after a cliff formation is complete it can be continued with reinforced concrete work, foundations, sloof, columns and beams.

Bonus photo, latest update

cliff slope formation, image by @halukha



Greetings from the tip of the island of Sumatra

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