Rubble Soling Under Floors and Foundations

Hard core soling can be done either by bricks or by rubble stones laid under floors / foundations, hand packed or as per specifications or requirement at site. Soling under floors, foundations and pavements provides cushion as well as strong subbase.

Rubble Stone Soling

The rubble stone generally used are of best variety of black trap / granite / basalt or other variety of stone available locally. The stone should be hard, durable free from defects and of required size as required at site or as per specification.

Preparation of Surface

The bed on which rubble soling is to be laid should be cleared of all loose materials, leveled, watered and compacted before laying rubble soling. Cable or pipe trenches if required shall be got done before the soling is started.

Procedure of Rubble Soling

Over the prepared surface, the stone should be set as closely as possible and well packed and firmly set. The stones should be of full height and should be laid so as to have their bases of the largest area resting on the sub-grade. Soling should be laid in one layer of 230mm or 150mm depth or specified thickness of soling with a tolerance of 25mm.

After packing the stones properly in position, the interstices between them should be carefully filled with quarry spoils or stone chips of larger size possible to obtain a bard, compact surface. Spreading of loose spoils or stone chips is prohibited.

The entire surface should be examined for any protrusions and the same should be knocked off by a hammer and all interstices should be filled with approved murrum. Excess murrum if any over the surfaces should be removed.

The surfaces should then be watered and consolidated with mechanical or sufficiently heavy wooden tampers and log-rammers.

After compaction, give the required slope or level and dense sub-base and the surface should present clean look. Adequate care should be taken by the contractor while laying and compacting the rubble soling to see that concrete surfaces in contact with soling are not damaged.

Quarrying of Stones for Construction Works – Site Selection and Methods

What is Stone Quarrying?

Quarrying is the process of collecting stones from the natural rock surfaces. Site selection and methods used for quarrying for construction works is discussed.

Quarrying of stone is completely different from mine. Mine belongs to underground operation only whereas quarry is carried out on exposed surface of natural rocks.

So, the stones collected through quarrying is used for various engineering purposes. Stone quarrying is generally done at hilly areas where large quantity of stone is available.

Site Selection for Quarrying of Stones

The quarry should be selected based on some conditions as follows.

• The site should be near to human living areas where labor and tools are always available, required materials also should be available.
• At least one of type transportation facilities (road or railway or port or all) should be available.
• Clean water source should be available near the quarry site.
• Good quality and quantity of stone should be available.
• The site should be far from permanent structures like bridges, dams etc. because the vibrations due to blasting in the site may cause harm to them.
• Non-living area should be available to dump the refuse obtained in quarrying.
• Proper drainage facility should be available.
• Geological information of site should be read.

Considerations for Quarrying of Stones

After the site selection, some important considerations are to be followed before starting quarrying of stones. Which are as follows:

• The rock surface should be properly checked for cracks and fissures. The presence of these may cause planes in the stones, along which they may split. Then, the quarrying will be easy and quick as well as economical.
• Layout should be prepared which contains different stages involved in quarrying operation.
• The machines used should be tested to operate them easily and quickly.
• If the top surface of site contains soft soil, then it should be removed and dumped.
• The removal of stones should be done carefully otherwise there may be chances of landslides or slips which can cause severe damage to the lives of labor.

Methods of Quarrying of Stones

Quarrying can be done by three methods as follows:

• Hand tools
• Machine quarrying
• Blasting

Quarrying of Stones using Hand Tools

In case of soft stones or for smaller works, quarrying is done by using hand tools. There are various ways to quarry using hand tools and they are:

• Excavating
• Heating
• Wedging

Excavating

Excavating is preferred in case of soft stone surfaces. Hammers, pick axes, shovels are used to excavate the stones.

Heating

The top surface of rock is heated by placing wood with fuel on it. The fire will be allowed for some hours and the top surface gets heated and separates from the rock. This separated portion is removed by pick axes, crowbars etc.

The stones obtained by heating will be in good shape if the rock formation contains horizontal layers at shallow depth. So, the stone obtained will be directly used for masonry works.

Wedging

This method is applicable when the rock contains cracks or joints in it. Steel wedges or steel points are put in these cracks or fissures and hit them with hammer.

Then the rock portion separates from parent rock. If natural cracks are there, then artificial holes are drilled in the rock and wedging is done.

Machine Quarrying of Stones

Machine quarrying is done by using channeling machines in the site. This type of machine is driven by steam, compressed air or electricity.

A groove is made using this machine around the rock and the horizontal holes are drilled underneath the block. Hence, the block gets separated from its bed.

A large groove of 24-meter length and 50 to 75 mm width and with a depth about 2 to 3.7 meter can be made using channeling machine. So, larger blocks of stones can be obtained using this method.

Marbles, lime stones, etc. are quarried using machine quarrying.

Blasting for Quarrying of Stones

In this method explosives are used to separate the stones from parent rock. This process is applied in case of hard stone or hard rock which does not contain any cracks or fissures.

The holes are drilled in the rock and explosives are arranged in the holes and blasted with proper safety measures. The stones obtained through this process are not larger in size.

So, the main purpose of blasting is to obtain small stones which are used as ballast for railway works, aggregate in concrete works etc.

How to Set Out a Building Plan on Ground with Procedure?

A building is set out in order to clearly define the outline of the excavation and the centre line of the walls, so that construction can be carried out exactly according to the plan. The centre line method of setting out is generally preferred and adopted.

Procedure for Setting Out a Building Plan on Ground

Fig.1: Example plan to be set out on the ground

1. From the plan (fig 1), the centre line of the walls are calculated. Then the centre lines of the rooms are set out by setting perpendiculars in the ratio 3:4:5. Suppose the corner points are a, b, c, d, e, f and g which are marked by pegs with nails on top.

2. The setting of the corner point is checked according to diagonals ac, bd, cf and eg.

3. During excavation, the centre points a, b, c, d, e, f, g may be removed. Therefore the centre lines are extended and the centre points are marked about 2m away from the outer edge of excavation.

Thus the points A1, A2, B1, B2 and likewise, are marked outside the trench. Centre line are shown clearly by stretching thread or rope. The centre points fixed 2m away from the excavation are marked with sit out pegs.

4. From the plan details, the width of excavation to be done is also marked by thread with pegs at appropriate positions.

5. The excavation width is then marked by lime or by with furrow with spade.

6. If the plan is much to complicated and follows a zigzag pattern, then the centre pegs are kept at suitable positions according to site conditions.

What is Artificial Stone? Its Types and Applications

What is artificial stone?

Artificial stone, which is also called casted stone, is constructed from cement, sand , and natural aggregate such as crushed stone. it is possible to provide certain surface textures to artificial stones.

Sometimes, specific pigments used to achieve certain color. The addition of pigments shall not exceed 15% by volume.

Artificial stone can be cast into complicated and considerably detailed forms and various sizes can be manufactured. Added to that, it can be reinforced to increase strength.

Finally, it is worth mentioning that artificial stones are casted easily and economically.

Figure 1 Artificial Stone

Artificial Stone Mix Ratio

Generally, cement and aggregate are mixed in proportion 1:3.

When artificial stones are selected for building constructions?

Artificial stone or cast stone will be used for construction when cost effective and durable natural stone cannot be achieved.

What are the types of artificial stones?

Different types of artificial stones along with their constituent materials and applications will be discussed briefly.

Ransom stone

It is also called chemical stone which its compression strength is at least 32 MPa. Ransom stone is manufactured by blending silica soda with cement to provide fancy and ornamental flooring.

Figure 2 Artificial Ransom Stone

Concrete block

Concrete blocks are used for the construction of steps, window, sills, and piers. It is cased in the construction site.

Artificial marble

It is constructed from Portland gypsum cement and sand using either precast or cast in situ technique.

For precast production technique, the casted artificial marble will be stripped from the mould after three days and then treated with liquid fluorite of magnesia solution at the age of five days.

After that, the stone is washed and wrapped with paper for 24 hours and treated again with the same solution, and it will be polished at the final stage at the age of 30days.

For in situ construction method, layer of prepared mixture is placed on a canvas, and the thickness of the layer shall be 1.5 mm greater than the required thickness of the stone to be constructed. The surface of the laid layer is rubbed and then polished properly.

Figure 3 Artificial Marble Stone

Bituminous stone

It is produced by impregnation of granite and diorite with refined tar. Functions of bituminous stone includes the provide wear, noise, and dust resistance stone surface.

Victoria stone

It is a granite piece which its surface is hardened by submerged the stone in silica soda for two months.

 Garlic stone

Garlic stone, which is employed as a surface drains and flag stones, is produced by mixing and casting Portland cement and iron slag.

Imperial stone

The procedure used to produce imperial artificial stone includes careful washing of finely crushed granite, mixing granite with Portland cement, cast the mixture into a favored form, and finally steam cure the casted imperial stone for twenty-four hours.

Figure 4 Artificial Imperial Stone