Explain the quality control testing before you allow starting the concreting work for the foundation, columns, slab and beams. There are two main tests to be done on concrete The slump test: the slump test shows the workability of concrete. The compression test: the compression test shows the best possible strength Concrete can reach in perfect conditions. Testing should always be done carefully. Wrong test results can be costly. The first step is to take a test sample from the large batch of concrete. This should be done as soon as discharge of the concrete commences.
The sample should be representative of the concrete supplied. The sample is taken in one of two ways: For purposes of accepting or rejecting the load: Sampling after 0. 2 m3 of the load has been poured. For routine quality checks: Sampling from three places in the load. The slump test is done to make sure a concrete mix is workable. The measured slump must be within a set range, or tolerance, from the target slump. Tools Standard slump cone,(100 mm top diameter x 200 mm bottom diameter x 300 mm high) Small scoop, Bullet-nosed rod,(600 mm long x 16 mm diameter) Rule, Slump plate (500 mm x 500 mm).
Method 1. Clean the cone. Dampen with water and place on the slump plate. 1|P a ge U. M. The slump plate should be clean, firm, level and non-absorbent. 2. Collect a sample. 3. Stand firmly on the foot pieces and fill 1/3 the volume of the cone with the sample. Compact the concrete by ‘rodding’ 25 times. 4. Now fill to 2/3 and again rod 25 times, just into the top of the first layer. 5. Fill to overflowing, rodding again this time just into the top of the second layer. Top up the cone till it overflows. 6. Level off the surface with the steel rod using a rolling action.
Clean any concrete from around the base and top of the cone, push down on the handles and step off the foot pieces. 7. Carefully lift the cone straight up making sure not to move the sample. 8. Turn the cone upside down and place the rod across the up-turned cone. 9. Take several measurements and report the average Distance to the top of the sample. 10. If the sample fails by being outside the tolerance (ie the slump is too high or too low), another must be taken. If this also fails the remainder of the batch should be rejected. The compression test shows the compressive strength of hardened concrete.
The testing is done in a laboratory off-site. The only work done on-site is to make a concrete cylinder for the compression test. The strength is measured in Mega Pascal’s (MPa) and is commonly specified as a characteristic strength of concrete measured at 28 days after mixing. The compressive strength is a measure of the concrete’s ability to resist loads which tend to crush it. Tools Cylinders (100 mm diameter x 200 mm high or 150 mm diameter x 300 mm high) (The small cylinders are normally used for most testing due to their lighter weight) Small scoop Bullet-nosed rod (600 mm x 16 mm) 2|P a ge
Steel float Steel plate Method 1. Clean the cylinder mould and coat the inside lightly with form oil, Then place on a clean, level and firm surface, the steel plate. 2. Collect a sample. 3. Fill 1/2 the volume of the mould with concrete then compact by rodding 25 times. Cylinders may also be compacted by vibrating using a Vibrating table. 4. Fill the cone to overflowing and rod 25 times into the top of the first Layer, then top up the mould till overflowing. 5. Level off the top with the steel float and clean any Concrete from around the mould. 6.
Cap, clearly tag the cylinder and put it in a cool dry place To set for at least 24 hours. 7. After the mould is removed the cylinder is sent to the laboratory Where it is cured and crushed to test compressive strength. 1. 2 propose different types of floor finishes for hall and brief their advantages and disadvantages FLOOR FINISHES floor covering is done by a suitable material to provide a good finish to the walking surface. Most commonly used materials are ceramic tiles, terrazzo, various stones, timber, carpets (hospital etc and applying various chemicals. In selecting suitable material following factors to be considered. . initial cost 2 . appearance 3. cleanliness 4. noiselessness 3|P a ge U. M. 5. durability 6. maintenance Tiling ceramic tiles of different sizes, colors, thicknesses are used for floor coverings. Ceramic tilling is dense and strong, easy to clean, long lasting and does not absorb smell, water or carry allergens. A well-prepared surface is a critical component to a good and lasting tile job. Titled flooring require hard sub grade which may be in the form of RRC slab or cement concrete. O the prepare sub sub-grade 12mm to 25mm thick layer of mortar is spread to act as bedding mortar.
This mortar is allowed to harden and then cement slurry is spread over it with the help of brush or otherwise. Now tiles are lightly tapped. The cement that oozes out through the joints due to tapping should be wiped clean immediately. These joints can be filled with tile grout. Procedure for tilling Floor should be tiled from the center of the floor, outwards, so that any cut tiles will be at the edges of the room. To find the center, each wall around the area to be tiled can be measured. Center points should be marked on the floor. The centre will be starting points.
Terrazzo floor covering Terrazzo is a mixture of cement and marble chips and the surface is polished to get a smooth finish. Terrazzo flooring generally constructed over a concrete base. A cement mortar layer is applied over the concrete base and metal strips to control cracking are fixed in the mortar layer. When this mortar layer is sufficiently hard, terrazzo mixture having one part of cement to two or three parts of marble is then rolled and troweled so that the mixture is well consolidated and marble is exposed to the maximum extent. After properly hardening, the surface can be grinded and polished.
Terrazzo flooring offers high durability and deep beauty. Its upfront cost is considerably higher than resilient flooring but when viewed long-term, it can actually be less expensive. Portland cement and polyacrylic-modified Portland cement floors hold finish nicely. Some pure epoxybased floors can be tough to finish due to its low moisture absorbency and hydrophobic nature (non-affinity for water). Avoid using high pH cleaners and acid-based products on terrazzo . Terrazzo was originally invented by Venetian construction workers as a low cost flooring material using marble chips from upscale jobs.