Frequently Asked Questions

Cement has its roots in ancient Rome, where around 300 BC, Romans developed a revolutionary binding material by mixing lime with volcanic ash (pozzolana) from regions like Pozzuoli, Italy. This Roman cement could set underwater, enabling construction of harbors, aqueducts, and massive structures. Iconic monuments such as the Pantheon (AD 126) and Colosseum still stand today, proving its durability. Roman concrete achieved compressive strengths estimated between 10–20 MPa, remarkable for its time. After the fall of the Roman Empire, this technology was largely lost for nearly 1,300 years. Modern cement emerged in 1824, when Joseph Aspdin of England patented Portland cement, named for its resemblance to Portland stone. Today, global cement production exceeds 4 billion tonnes annually, making it the backbone of modern infrastructure worldwide.

Cement mainly consists of calcium oxide (CaO ~60–65%), silica (SiO₂ ~20–25%), alumina (Al₂O₃ ~5–8%), and iron oxide (Fe₂O₃ ~2–4%), along with small amounts of gypsum (3–5%)

Buy a major plant cement. Cement should not be more than 6 months old. Cement should be fine in texture, not grainy. Cement should not have lumps and should be moisture free.

C₃S (Tricalcium silicate) + Water → C-S-H gel + Calcium hydroxide + Heat C₂S (Dicalcium silicate) + Water → C-S-H gel + Calcium hydroxide (slower reaction) C₃A + Gypsum + Water → Ettringite (controls setting time) C-S-H (Calcium Silicate Hydrate) is the compound that gives cement strength and durability

Cement is pumped from silos into the wire bags. This incorporates air with huge pressure into the bag. Hence, the bag should have tiny pores to allow the air to escape otherwise the bag may blast off due to air pressure.

It depends on the grade of concrete. For M15, it is 208 kgs of cement in 1 m3 of concrete while in M25 it is 360 kgs of cement in 1 m3. For internal plaster, cement : sand ratio is 1:6 while for external it is 1:4.

OPC cement gains its full strength in 28 days while PPC cement reaches 98% of strength in 28 days and then gradually increases over a long time.

Cement bags should be stored in a cool & dry shade. Protect it from rodents like mice. Do not pile up more than 10 bags in a single pile. In case of rain or high humidity, cover it up with tarpaulin. Do not use hooks to carry cement bags.

Not using cover blocks in RCC may result in displacement of steel bar from its position during vibrating the concrete. Absence of cover blocks may result in exposure of steel rebars and may result in corrosion of rebars.

Mostly, it is written on drawings. For slabs generally it is 20/25 mm while in beam/columns it is 30mm.

Thumb rule is there should be 1 cover block per 10 sq ft. If the structure is heavy, you may need more than this.

Cover blocks are made up of concrete. So, the concrete - to - concrete bond is strong & unmatched as compared to foreign materials with concrete. Cover blocks come with a binding wire which is able to hold the rebars in their position throughout the concreting.

AAC blocks rise up to 3x after auto clave. It is puffed with air to make it lighter in weight.

AAC blocks contain trapped air and air is a bad conductor of heat and sound.

AAC blocks come with either 4Mpa+ OR 5MPa+ strengths. AAC blocks are used in frame structures where the walls do not transfer the load of the structure. So, AAC blocks have to carry their own weight only and 4MPa+ is enough for that. So, practically it doesn’t matter whether AAC blocks are stronger than bricks or not.

Auto clave can be taken as an oven. AAC blocks’ masonry is filled upto 1/3rd of the height of the mould and then transferred to auto clave for baking purpose, where it rises and gets air trapped in it.

Plaster is good in compressive strength but weak in tensile strength. So, any vibration / elongation of the wall may result in cracks. Also, weak bonding of old-new plaster may result in cracks.

Glass fibre mesh has good tensile strength which eliminates the weakness of plaster. So, in case of old-new bond or vibration or elongation of walls, glass fibre mesh will resist the cracks with its high tensile strength.

Glass fibre mesh can be used in plaster, near electrical conduits, pipe fittings, sandwiched between waterproofing layers, etc.

Just sandwich it between two layers of plaster / waterproofing.

It depends on the quality of material used and workmanship. Generally speaking, with good workmanship, SBR coating can last up to 3-5 years, acrylic & cement based up to 10 years, and PU based up to 25+ years.

Yes. For old structures, make sure the surface is strong enough. Sometimes, the surface on which waterproofing is done, itself gets detached from the mother structure. One should apply primer before doing waterproofing on old structures for durability. For leaking structures, focus should be to stop the leakage first by repairing/diverting the source of water and then do waterproofing. To stop the leakage, injection grouting and sealants can be used.

Integral waterproofing compounds are those which are added to cement mortar and then the coating is done. They cannot be used independently without cement. For example, SBR. Liquid waterproofing includes acrylic / PU / cement / bitmen based compounds that can be independently applied on the surface using brush, rollers or sprayers. They may need a primer coat before its application. Membrane waterproofing is a “sheet” or membrane that is laid on the surface to prevent water ingressing. On it, screeding is done to give load and stability to the membrane so it doesn’t move and remains stuck to the surface. For example, PVC / bitumen based membranes.

Mostly they come from cracks / pin holes on the terrace (floor/parapet/covering area) or external walls or chhajjas. Or it can be internal leakage from plumbing pipes which is a bit trickier to find.

The positive side is where the water is in direct contact with the structure. Waterproofing on the positive side prevents water ingress at the very source. The negative side is on the other side of the structure where the water infiltrates. Waterproofing on the negative side prevents water ingress after it has travelled through the structure.

Tile adhesive is a mix of cement, fine grinded sand and polymers while the mortar has no polymers in it. Mortar works on interlocking effects so it can be only used for high porosity ceramic tiles, while tile adhesive gets adhesion strength from polymers so it is used for fixing low porosity or vitrified tiles and stones.

Yes, tile adhesives can be used for tile on tile fixing but here’s the important point. Make sure that old tiles are properly fixed onto the surface and have no dumb sound. Then, hack the old tiles for better interlocking. Apply adhesive on both the sides i.e. on old tiles as well as the back of new tiles. Properly press new tile over the old tiles such that there is no air entrapped in between.

Following the thumb rule, it is 1kg of adhesive used to fix 1 sq ft of tiles.

Vitrified tiles should be cleaned first. Water should be sprinkled on the substrate so that it doesn’t suck water from tile adhesive. Adhesive should be applied both the sides i.e. on substrate and on tile using trowels. Tile should be pressed properly against the substrate for better bonding, use mallet here. For endurance, pick up the freshly installed tile and see if trowel marks have vanished. This is the sign of proper pressing. If not pressed properly, tiles may debond in future due to air pressure. After 24 hours of tile fixing, grout the space between the tiles.

Providing a gap between tiles / stones is necessary to provide room for expansion / contraction. If not then tile/stone may get debond from the surface. But we cannot leave this gap open as it may gather dirt and pests. So, there is a need to fill this gap but not with any ordinary material. We need material which can expand / contract along with tile/stone so that together they act like a system. These properties are fulfilled with grouts.

Width must be greater than 3mm. If grouting is done in less than this gap, it may strip out from the gap and leave a hollow space between tiles.

Cement grout consists of cement, polymers and colour tint while epoxy consists of resin, hardener and filler powder (color). Cement based grouts are much cheaper than epoxy. Cement grouts are used in areas like living rooms, bedrooms, offices, commercial spaces, etc. They may fade when exposed to harsh sunlight for a long time, in constant touch with water (like in washrooms). They get easily scratched and are not resistant to water. While epoxy on the other hand is highly durable, resistant to water, chemicals, high in density, long lasting color, food grade certified, and can withstand harsh temperatures. They are used in areas like kitchens, washrooms, hospitals, etc.

Some may apply cement grout first and on that the epoxy so that it gives a premium touch of epoxy but at much cheaper rates. As per our recommendation, one should apply full depth epoxy only as it gives the best durability. But if budget is the constraint, at least apply epoxy half the thickness of tile or 5mm, whichever is the max.