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Topping Concrete

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Topping concrete is defined as a layer of high strength concrete placed on an old to prevent a dense, abrasion-resistant surface, to increase structural depth and strength of the base concrete. Evolution is required before the laying of topping concrete over an existing concrete surface.  The existing concrete must be hard and strong.Weak and fragile concrete bases are not preferred as they don’t achieve adhesion between the old and new concrete. Preparation is the important step in laying of topping concrete. The surface must be uniform, clean and free from dust particles or other contamination. If the base concrete is finished smoothly then the surface must be made course by the help of mechanical scabbing or scarification machine, so that the course aggregate of the base slab is exposed. The loose debris, dirt and dust must be removed using a vacuum cleaner. Before placing the topping concrete, a small amount of water is to be poured in the base slab and the absor
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Hairline crack in concrete

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Hairline cracks are observed in freshly placed concrete and that creates plastic shrinkage. The causes for these cracks to show up can be due to the variations in air temperature, concrete temperature, relative humidity and wind velocity at the surface of the concrete. These factors can cause high rates of evaporation in either hot or cold weather. Other factors for hairline cracks are water loss due to absorption by subgrade, formwork or aggregate, bleeding and sedimentation, poor workmanship and negligence, alkali-aggregate reactions, type and content of Portland cement and supplementary cementitious materials (fly ash, silica fume,etc.), type and dosage rate of chemical admixtures, construction operations like screeding and finishing operations. There are ways to prevent hairline cracks such as use of fog nozzles to saturate the air above the surface, use the plastic to cover the surface between final finishing operations, use of  wind breakers  to reduce the  win
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Control Joints in Concrete Slab

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Control joints are provided in a concrete slab to reduce cracks formed due to shrinkage. The specifications of the control joints such as the depth, timing and place of the cut play an important role in the efficiency of the control joint. The time when the concrete slab is saw-cut to make control joints is an important aspect for the efficient use of control joint. When the concrete is sawed with the help of blade before it has reached its initial setting time, the aggregates may strew out of the concrete slab and leave a messy, weakened edge along the joint. This effect is known as Ravelling. Sawing too late can result in uncontrolled cracking as the concrete contracts during curing. It is recommended to place the control joints in the centre of the slab dividing the concrete into equal segments. The spacing of the joints is in the range of 24 to 36 times the thickness of the concrete slab. The factors that determine the location of control joints are: Continui
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#VastuFor Home – Colours for Home

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Colours are playing an important part in the house. If we coloured each wall with same colour, it will end up looking bad therefore it is important to have a balance of colour in the entire house. Depending upon in which direction room is located best suitable colours have to decide. Each and every room in the house is different because every room has specific purpose. If we are using wrong colours at wrong places it will mess up. For master bedroom, it is advisable to use brown, blue and pink colours. Red is not advisable to use. Red colour will bring fights within the family, with neighbours. Whereas the blue and pink are masculine and feminine colours respectively and the brown colour gives stability. Use light green and light yellow colour for kid’s room that will help them to concentrate more on studies without wasting time. Avoid using dark blue colour in kid’s bedroom. For living room, use more of white colour.  You can use tinges of some other colours
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Types of Grouts for Tile installation

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Grouts are used to fill the joints between the tiles. Grout material used must prevent moisture from penetrating the underlying surface. To remain waterproof for the entire life span it has to be well maintained and periodic sealing should be done. There are mainly four types of grouts used for tile installation namely, cementitious grout, epoxy grout, polymer grouts, and furan grouts. Cement Grouts for Tile Installation Cement grout constituents are Ordinary Portland Cement, water-retentive additive, Coloured pigments and filler particles of different sizes. This grout is used from many years and this can be used in residential and commercial both the purposes. Some colour pigments can be added to the grout to mix and match with the tile. There are subdivision of cement grout. Ø   Sanded Cement Grout: In this type of grout sand is used largely. It is quite affordable compared to unsanded grout. Sanded grout provide tight lock and gives a clean and finishe
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Techniques to Repair and Restore Strength of Structural Members

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When structure is gets damaged it is essential to restore original strength of building so that it can continue to serve the purpose. It is necessary to locate the damages and repair them to restore the original strength of structures. These repair works can be done in many ways. Repair of Small Cracks Small cracks can be repaired by injection of epoxy. Surface can be cleaned and make it dust free. Place the plastic ports along the crack surface on both sides of the member and secure it in place with an epoxy sealant. When the sealant has cured, inject the epoxy resin beginning the lowest part of the crack at one part at a time in case of vertical or at one end of the crack in case it is horizontal structural member. It should be remembered that the distance between ports should be more closely spaced as the cracks gets smaller and pressure of injection should be higher. This is to ensure that epoxy is injected throughout the length of the crack. This technique
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Steam Curing of Concrete

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Steam curing of concrete is the method of curing the concrete elements in water vapour. This curing is performed either under atmospheric pressure or high-pressure steam. This method is used where there is a need for accelerated strength gain and the concrete requires additional heat to perform hydration. This is done in low temperature zone. This technique is used for gaining high early strength and this requires for the manufacture of precast and prestressed concrete units. Steam Curing can be performed by two methods: Ø   Steam Curing of Concrete at Atmospheric Pressure: The steam curing process is performed within a temperature range of 70 to 90F per hour which is merely dependent on the size and the shape of the concrete element. In this steam curing is done in an enclosed chamber in order to avoid any sort of heat loss and moisture. The properly hardened concrete is applied to the steam enclosure after a delay period of 3 hours. It is not exposed directly to
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