Civil Engineering

What to plaster your House?, these are the materials you will need

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house plastering

In many places, the term, plaster In building construction means cement sand rendering of block constructed walls.

Materials you will need for this type of works are;

Ordinary Portland cement.

Fine Sand.

Clean water.

Sand required should not contain too much clay, or too cohesive. It must also not be too loose. Water used must be clean water of drinking quality. Using dirty water can affect the quality of the plaster or render.

Workmanship.

Skilled renderers and  unskilled labourers are required. A skilled renderer is usually a mason. Good quality rendering depends on the skill of the renderer, so get a good one to do the work for you. The unskilled labour, hand mixes the plastering material and transports it to the point of application.

Mixing ratio of Cement Sand rendering

The mixing ratio is usually 1:6, that is one part of cement to 6 parts of sand. For stronger rendering the mixing ratio can be as high as 1:3.

Calculation of the amount of cement and sand  required.

A skilled mason can easily estimate the amount of cement and sand required. You can also do it yourself. Click on the article link below for details;

https://specsfinder.info/2021/10/12/how-to-calculate-the-number-of-cement-bags-and-quantity-of-sand-required-for-plastering/.

How Ceramic Floor tiles are made

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ceramic floor tiles

The main material used in the production of ceramic tiles is clay. Clay is readily available in different types and in large quantities. Different types of clay and other similar binding materials can be combined in a particular proportion to create ceramic tiles.

The 3 major types of clay available are earthenware, stoneware and porcelain. 

earthenware clay
stoneware clay

The earthenware clay is red in colour while the stoneware and porcelain are classified as white clay. All the 3 above mentioned types of clay are suitable for making ceramic floor and wall tiles.

The process of making ceramic tiles industrially will be discussed under the following stages.

Grinding the raw material

Moulding

Initial heating

Painting/ glazing

Final heating

Making of ceramic floor tiles in a factory

Grinding the raw material

clay and other binding and waterproofing substances are grinded in required proportions to smooth power. This is done using an industrial grinder.

Moulding 

To the powder mixture a very little amount of water is added and thoroughly mixed to make it plastic. The powdery mixture is then placed into a mould and compressed under very high pressure and temperature to form a flat solid mass that has been shaped into the required time size.

Initial heating 

Before the tiles can be glazed it needs most of the moisture to be taken out. This can be done by heating the tiles in an oven. The tiles are heated up to a temperature of over 900°C and then cooled. 

Painting/glazing

Next the tiles are painted and or glazed.

Painting gives the tiles its waterproofing properties and aesthetic look. Glazing does similar work in addition to design and engravings.

Final Heating 

After the tiles have been given its waterproof and aesthetic look. It is heated in an oven for the final time to dry up all the moisture and make the tiles stronger in the process. Temperatures in the oven are above 1000°C.The heating process can last for several hours, after which it is allowed to cool completely. After this final process, the ceramic tiles are ready for packaging and distribution to sale outlets.

About the RCC 51 Column Load Take Down Spreadsheet to BS 8110

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Rcc 51 screenshot

In reinforced concrete pad footing design, one of the major questions asked is how to calculate the axial load and moments acting on the foundation columns.

Doing these calculations by hand can be tedious and time consuming.

You can use RCC 51, a spreadsheet program  that calculates the load from the structure that is acting on the pad footing.

It is known as column load take down. Recall that columns carry loads transferred from the slab and beams down to the pad footing foundation. RCC 51 will help you calculate the load acting on a particular pad footing as well as moments. It can also check if the column parameters you entered will lead to a short or slender column.

RCC51 designs to BS 8110 1997.

You can download RCC51 from RCC spreadsheets PAGE.

Or click the link below

https://docs.google.com/spreadsheets/d/1o4NtAAbw54RyciBhQkcO1UAPpGK_xY8A/edit?usp=drivesdk&ouid=106276104383891115503&rtpof=true&sd=true

Frame Structure Analysis ( reinforced concrete design) RCC 21.

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RCC subframe analysis is a structural analysis program created with Microsoft Excel. It is used for structural analysis and design moments and shear forces of reinforced concrete framed structures. It is very effective for the calculations of design moments of columns and beams. 

It can handle up to six spans and seven supports. It gives you design beam moments as well as column moments above and below the beams.

It also considers the main 3 load cases so the design moments calculated are actually of the worst case.

Once you know what you are to fill in the input boxes ( blue texted ) you will certainly get the correct moments and shear forces values.

It is very easy to understand once you know how the structure you are designing is framed. For better understanding on how to use this software I will refer you to framed structural analysis examples in the book titled Reinforced Concrete Design by Mosley & Bungey 5th edition. Check out the worked examples on pages 30-32 & 33 – 39.

If you are a student, this software will greatly help you in your knowledge of structural analysis. It will greatly aid your what if scenarios. 

If you are a professional and you don’t have the money to purchase analysis and design software this is a great free alternative.

To download the software visit THIS PAGE

then scroll down till you see RCC 21 Subframe Analysis.xls and download.

Cement plaster/render; how its done

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Cement and sand are mixed in the dry state in the adopted ratio. For plastering of walls, a cement sand ratio 1: 6 is adequate.

Water is added to achieve a workable plasticity.

Cement plaster can be applied in 2 coats or as a single coat. Plaster thickness for walls ranges from between 12mm to 20mm. Plaster thickness of between 12 and 15mm can be applied as a single coat while thickness above 15mm are applied in 2 coats.

Cement Plastering in a single coat:

Cement plaster ( single coat)

The plaster is first applied roughly at the required thickness on the wall. Wait for about 20 minutes, (After the plaster starts to set), and gradually smooth it out with a straight long rod or plank. The plastering is then finished off with a hand trowel and finally foaming. The finished work should be straight and smooth.

Cement plastering in 2 coats

Cement plaster ( double coat)

This method is necessary when the plaster thickness is above 15mm. The first coat is applied roughly on the surface of the wall. The surface of the plaster is then made zigzag to receive the second coat. The second coat can be applied when the first coat sets ( about 30mins upwards). However it should be applied by the second day at the latest.

What to Plaster a Wall? See what you will need

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Plastering a wall means you want to give the wall a smooth and level finish with the use of a cementitious compound. Plaster is a protective or decorative coating for walls and ceiling.If a wall is constructed of sandcrete blocks then chances are high that it will be plastered to give a very smooth aesthetic finish.

Difference between plastering and rendering

“plaster” usually means a material used for the interiors of buildings, while “render” commonly refers to applications on external walls.

Types of plaster

Gypsum Plastering
  • Gypsum plaster: Also called plaster of Paris, it is calcium sulphate hemihydrate a white cementing material composed of gypsum, retarded and hardeners. It is applied to the wall in a plastic state. It thereafter hardens by the chemical combination of the gypsum and water. Gypsum plaster are usually supplied in bags.
Gypsum plaster bag
  • Cement plaster: This is a mixture of portland cement and sand. It is applied in the plastic state after mixing with water. It thereafter hardens after the chemical combination of the cement and water. Ready mix cement plaster is supplied in bags.
Ready mix cement plaster

Cement plaster

This is the most commonly used plaster material because it is cheaper and more versatile than the gypsum plaster.

Ready mix cement plaster is available but expensive. It is more economical to mix on site, cement, sand and water and use it to plaster / design walls.

Materials needed for cement plaster

  1. Cement: usually supplied in 50kg bags.
  2. Plaster sand. A type of fine sand that bonds very well with cement in the presence of water.
  3. Clean water of drinking quality.

Mixing of cement and sand for plaster works

Thorough mixing of cement and sand is first done in the dry state. After that water is added and mixed to a workable plastic state before application. For plastering works, the cement sand ratio is usually 1:4 or 1:6. Ratio 1:6 being the more commonly adopted ratio.

To calculate the amount of cement and sand need for wall plastering, read the article below by clicking on the link.

How to calculate the number of cement bags and quantity of sand required for plastering