Lab report concrete

1.1 Introduction In modern days, concrete is one of the most commonly used materials for construction, such that it have a low cost but high compressive strength. Concrete is a mixture of cement, aggregate and water. Concrete can be divided into different types at which different type of concrete have specified properties for specific usage. After curing, hardening of concrete is undergone which the mechanical properties of the concrete would change with time. It is due the hydration in the water tank. In this lab experiment, regular Portland cement is used to check out the development of strength of concrete from time to time, that is the 7th day and 28th day after the curing of concrete. Workability of concrete is also an important measure for determining the quality of fresh concrete. As it is important to ensure the concrete mixture suits the specification of materials required that is able to be shaped into desired parts for construction.. For freshly made concrete, several tests are conducted to determine the workability of concrete. Tests include slump test, slump test, V-B test and compacting factor test. Results will be compared with the British Standards in order to check for the workability. On the 7th day and 28th day after curing, the concrete will be conducted severals tests to determine the strength and durability of concrete. Tests include Schmidt Hammer Test, Cube Crushing Test, Ultrasonic Pulse Test, Flexural Strength Test, Equivalent Cube Test and Split Cylinder Test. 1.2 Objectives 1. To study how concrete is made 2. To determine the workability , strength and durability of concrete 3. To study the changes of mechanical properties of hardened concrete on the 7th and the 28th day 2. Sieve Analysis of Aggregates 2.1 Objective 1. To determine the grading of the aggregates by sieving the concrete looking for percentage passing of different sizes of sieve. 2. To determine the workability by comparing the result with the British Standard limit (B.S. 1881) 3. To consturct the grading curve of the mixed aggregates 2.2 Apparatus and materials Apparatus: 1. Sieving machines 2. Test sieves 3. Electronic Balance Materials: 1. Fine Aggregates – Crushed Granite rocks with a theoretical maximum size of 5mm 2. Coarse Aggregates – 10mm size aggregates and 20mm size aggregates made of granite rocks 2.3 Procedure 1. 5kg of 20mm aggregate is first weighted then is placed into the sieving machine with different sieve sizes of sieve plates arranged in order according to the British Standard. The sieve plates should be arranged as follow from the top to the bottom: 25mm, 20mm, 10mm, and 5mm. The sieving machine is then turned on. After the machine stops, aggregate retained on each sieve will then be weighted accordingly and recorded. 2. After clear all the aggregate in the sieves, Step 1 is repeated with 2kg of 10mm aggregate using the same set of sieve. 3. 0.5 kg fine aggregates will be sieved using another sieving machine with sieve plates arranged as follow from the top to the bottom: 5mm, 2.36mm, 1.18mm, 600μm, 300μm and 150μm. The sieving machine is then turned on. After the machine stops, aggregate retained on each sieve will then be weighted accordingly and recorded 4. The percentage passing each sieve of the 3 sizes of aggregates is calculated for the plotting of a grading curve. .........................................CONTINUED..........................................