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What type of material is reinforced concrete?
Concrete is composed of cement and other cementitious materials such as fly ash and slag cement, coarse aggregate made of crushed stone, fine aggregate such as sand, water, and chemical admixtures. In reinforced concrete, steel is introduced in to the concrete. In plain concrete, no steel reinforcement is introduced. Generally tensile and compressive strength is taken by reinforced concrete and only compressive strength is taken by plain concrete
What is the compressive strength of cement mortar?
Compressive strength measures the largest compression force the material can withstand before it loses its shape or fails.
What is the procedure and formula of core cutting test of concrete and bituminous?
(hope this help) 75mm, 100mm or 150mm diameter cores are taken on site using state of the art core cutting machines. Cover meter is used to locate the reinforcement steel before core cutting. This prevents structural damage to the RCC member by avoiding the reinforcement. These cores are dressed in our lab and tested using standard compression testing methods to determine compressive strength and arrive at equivalent cube strength of concrete. IS Codes applicable: IS : 456 / IS : 516 / IS : 1199 Applications: Assessment of strength. Study of aggregates used in the mix design. Assessing probable causes of failures/problems. Equipment Used: Core cutter. Core compression testing machine. Test basis: A core sample is the actual representation of the material used in the structural element. When processed and subjected to load, it fails at a particular load, giving a fair idea of its compressive strength. Methodology: Step1: Reinforcement Mapping. By using a special instrument, based on eddy currents, the reinforcements are mapped in the structural member. Step 2: Core cutting. Cores are taken using special diamond cutters of 75 mm, 100 mm or 150 mm diameter. Locations are selected to avoid steel so as to minimize the damage to the structure. Step 3: Dressing. The edges of the core are smoothend using grinding and cutting wheels and epoxy mortar is applied on both sides for capping. This ensures that the ends are approximately at 90% to the axis and are within 0.05 mm plane ness. Step 4: Immersion in water The core samples are immersed in water for 48 hours. The cores are weighed before and after immersion. Step 5: Compression testing. The cores are then subjected to compression forces on compression testing machine. The breaking point is observed. Step 6: Reporting. Based on the lab report, sizes of the core etc. an equivalent cube strength is calculated for the concrete applying necessary correction factors. The density, core strength and equivalent cube strength are reported. Influencing factors: Core diameter and length (h / d ratio) Proper capping and hydration of the cores as per IS code. Old/new/Mixed (jacketed) concrete. Understanding results: The result is normalized for comparison with compressive test results of a standard cube. This is done so that the cube results can be compared with the core results. Standard correction factors as per IS code are used for this purpose. This value may not be the same as the core strength. Following are the factors which affect the compressive strength of extracted concrete cores: Size of stone aggregate: If the ratio of diameter of core to maximum size of stone aggregate is less than 3, a reduction in strength is reported. For concrete with 20mm size aggregate, 50mm dia core has been tested to give 10% lower results than with 10mm dia cores. Presence of transverse reinforcement steel: It is reported that the presence of transverse steel causes a 5 to 15% reduction in compressive strength of core. The effect of embedded steel is higher on stronger concrete and as its location moves away from ends, i.e. towards the middle. However presence of steel parallel to the axis of the core is not desirable. H/D ratio: This has been already discussed above. However its value should be minimum 0.95 and maximum 2. Higher ratio would cause a reduction in strength. Age of concrete: No age allowance is recommended by the Concrete Society as some evidence is reported to suggest that in-situ concrete gains little strength after 28 days. Whereas others suggest that under average conditions, the increase over 28 days' strength is 10% after 3 months, 15% after 6 months. Hence it is not easy to deal the effect of age on core strength. Strength of concrete: The effect in reducing the core strength appears to be higher in stronger concretes and reduction has been reported as 15% for 40 MPa concrete. However a reduction of 5 50 7% is considered reasonable. Drilling operations: The strength of cores is generally less than that of standard cylinders, partly as a consequence of disturbance due to vibrations during drilling operations. Whatever best precautions are taken during drilling, there is always a risk of slight damage. Site conditions vis-a-vis standard specimens: Because site curing is invariably inferior to curing prescribed for standard specimens, the in-situ core strength is invariably lower than the standard specimens taken and tested during concreting operations. Engineer Muhammad Mubashir Refrences http://theconstructor.org/concrete/core-sampling-and-testing-of-concrete/2865/ http://www.aaryanengineers.com/core_testing.html
Why steel is used to reinforce concrete explain it?
There are two main loading conditions that concrete under goes. These are Compression and Tension. Concrete is very strong in compression and is very weak in Tension (pulling apart). Concrete has so little strength to resist tension it is assumed to have no strength in tension. When civil engineers design concrete structures they can determine where the tension and compression will be located. Steel is added to give the concrete tensile strength. For Example a concrete beam when loaded from the top will experience compression on top section of the beam. The top portion of the beam will push inwards creating compression while the bottom section will pull apart creating tension. (Imagine a smile shape). :) Therefore reinforcement will be needed in the tension area (bottom).
How do you determine the characteristic strength of concrete?
Strength of concrete is tested by destructive testing of concrete test core samples that are taken at the time the concrete is poured. The test cores are about 7" diameter x 16" tall plastic containers. A number of samples are taken. One will be tested at 7 days, another at 28 days. A test report is provided to the firm responsible for paying the bill. The testing method is: place the core sample (removed from the plastic container), in the test machine; the machine will compress the sample until it breaks. A gauge measures the force applied and at what point it breaks. Concrete usually breaks at 30-40% higher than the minimum specified, because the concrete company has to guarantee the concrete strength. Concrete strength is specified as: 2500 pound, 3000 pound, 4,000 pound, 6000 pound concrete. Sidewalks and non load bearing loads use the lighter weight concrete, bridges and buildings carrying loads will use a higher strength concrete. The strength is adjusted by adding or subtracting the percentages of the raw materials in the mix; limestone, water, sand, and mortar mix.
What is the compressive strength of M10 concrete at 7 days?
For M25 grade concrete the seven days crushing for site condition shall be not less than 67 % of M25, i.e not less than 16.75 N/mm2 But for target strength of M25 for mix design taken i.e for M25 it is 32 and the 7 days strength shall not be less than 22 N/mm2
Why is the 28-days compressive strength of concrete generally specified?
It is attributed to two reasons: 1. Strength of concrete grows faster in initial days and this process of gaining strength slow down with time. This can be said as stabilization in value of gained strength of concrete. After approximately 20 or some more days, strength value get stabilize and does not change too much with time. Therefore, compressive strength is taken after approximatley 3 weeks time. 2. These tests have to performed practically and date record is needed to be maintained. Therefore, if test duration is a multiple of 7 (7 weekdays) then it is more easy to remind. It is the reason we have 28=7x4 days to note down compressive strength of concrete. for ex: if we start test on monday then we know that after 4 weeks on same time on monday we can finish the compressive strength test.
What is the value of modulus of elasticity of concrete?
According to the "Structural Engineer's Pocket Book" concrete commonly has a modulus of elasticity in the range of 17 - 30 GPa.The exact value of modulus of elasticity depends on the concrete's uniaxial compressive strength after a cure time of 28 days.These values are related using the following:Emc = 4700 x sqrt(UCS)Where:Emc = Elastic Modulus (MPa)UCS = Uniaxial Compressive Strength of Concrete after 28 days (MPa).Source:Cobb, F. (2009). Structural Engineer's Pocket Book, Second Edition. London, Butterworth-Heinemann.
What type of material is reinforced concrete?
Concrete is composed of cement and other cementitious materials such as fly ash and slag cement, coarse aggregate made of crushed stone, fine aggregate such as sand, water, and chemical admixtures. In reinforced concrete, steel is introduced in to the concrete. In plain concrete, no steel reinforcement is introduced. Generally tensile and compressive strength is taken by reinforced concrete and only compressive strength is taken by plain concrete
What is the compressive strength of cement mortar?
Compressive strength measures the largest compression force the material can withstand before it loses its shape or fails.
What is the procedure and formula of core cutting test of concrete and bituminous?
(hope this help) 75mm, 100mm or 150mm diameter cores are taken on site using state of the art core cutting machines. Cover meter is used to locate the reinforcement steel before core cutting. This prevents structural damage to the RCC member by avoiding the reinforcement. These cores are dressed in our lab and tested using standard compression testing methods to determine compressive strength and arrive at equivalent cube strength of concrete. IS Codes applicable: IS : 456 / IS : 516 / IS : 1199 Applications: Assessment of strength. Study of aggregates used in the mix design. Assessing probable causes of failures/problems. Equipment Used: Core cutter. Core compression testing machine. Test basis: A core sample is the actual representation of the material used in the structural element. When processed and subjected to load, it fails at a particular load, giving a fair idea of its compressive strength. Methodology: Step1: Reinforcement Mapping. By using a special instrument, based on eddy currents, the reinforcements are mapped in the structural member. Step 2: Core cutting. Cores are taken using special diamond cutters of 75 mm, 100 mm or 150 mm diameter. Locations are selected to avoid steel so as to minimize the damage to the structure. Step 3: Dressing. The edges of the core are smoothend using grinding and cutting wheels and epoxy mortar is applied on both sides for capping. This ensures that the ends are approximately at 90% to the axis and are within 0.05 mm plane ness. Step 4: Immersion in water The core samples are immersed in water for 48 hours. The cores are weighed before and after immersion. Step 5: Compression testing. The cores are then subjected to compression forces on compression testing machine. The breaking point is observed. Step 6: Reporting. Based on the lab report, sizes of the core etc. an equivalent cube strength is calculated for the concrete applying necessary correction factors. The density, core strength and equivalent cube strength are reported. Influencing factors: Core diameter and length (h / d ratio) Proper capping and hydration of the cores as per IS code. Old/new/Mixed (jacketed) concrete. Understanding results: The result is normalized for comparison with compressive test results of a standard cube. This is done so that the cube results can be compared with the core results. Standard correction factors as per IS code are used for this purpose. This value may not be the same as the core strength. Following are the factors which affect the compressive strength of extracted concrete cores: Size of stone aggregate: If the ratio of diameter of core to maximum size of stone aggregate is less than 3, a reduction in strength is reported. For concrete with 20mm size aggregate, 50mm dia core has been tested to give 10% lower results than with 10mm dia cores. Presence of transverse reinforcement steel: It is reported that the presence of transverse steel causes a 5 to 15% reduction in compressive strength of core. The effect of embedded steel is higher on stronger concrete and as its location moves away from ends, i.e. towards the middle. However presence of steel parallel to the axis of the core is not desirable. H/D ratio: This has been already discussed above. However its value should be minimum 0.95 and maximum 2. Higher ratio would cause a reduction in strength. Age of concrete: No age allowance is recommended by the Concrete Society as some evidence is reported to suggest that in-situ concrete gains little strength after 28 days. Whereas others suggest that under average conditions, the increase over 28 days' strength is 10% after 3 months, 15% after 6 months. Hence it is not easy to deal the effect of age on core strength. Strength of concrete: The effect in reducing the core strength appears to be higher in stronger concretes and reduction has been reported as 15% for 40 MPa concrete. However a reduction of 5 50 7% is considered reasonable. Drilling operations: The strength of cores is generally less than that of standard cylinders, partly as a consequence of disturbance due to vibrations during drilling operations. Whatever best precautions are taken during drilling, there is always a risk of slight damage. Site conditions vis-a-vis standard specimens: Because site curing is invariably inferior to curing prescribed for standard specimens, the in-situ core strength is invariably lower than the standard specimens taken and tested during concreting operations. Engineer Muhammad Mubashir Refrences http://theconstructor.org/concrete/core-sampling-and-testing-of-concrete/2865/ http://www.aaryanengineers.com/core_testing.html
Why steel is used to reinforce concrete explain it?
There are two main loading conditions that concrete under goes. These are Compression and Tension. Concrete is very strong in compression and is very weak in Tension (pulling apart). Concrete has so little strength to resist tension it is assumed to have no strength in tension. When civil engineers design concrete structures they can determine where the tension and compression will be located. Steel is added to give the concrete tensile strength. For Example a concrete beam when loaded from the top will experience compression on top section of the beam. The top portion of the beam will push inwards creating compression while the bottom section will pull apart creating tension. (Imagine a smile shape). :) Therefore reinforcement will be needed in the tension area (bottom).
Why water always taken as standard?
Water is not often taken as a standard in chemistry.
How do you determine the characteristic strength of concrete?
Strength of concrete is tested by destructive testing of concrete test core samples that are taken at the time the concrete is poured. The test cores are about 7" diameter x 16" tall plastic containers. A number of samples are taken. One will be tested at 7 days, another at 28 days. A test report is provided to the firm responsible for paying the bill. The testing method is: place the core sample (removed from the plastic container), in the test machine; the machine will compress the sample until it breaks. A gauge measures the force applied and at what point it breaks. Concrete usually breaks at 30-40% higher than the minimum specified, because the concrete company has to guarantee the concrete strength. Concrete strength is specified as: 2500 pound, 3000 pound, 4,000 pound, 6000 pound concrete. Sidewalks and non load bearing loads use the lighter weight concrete, bridges and buildings carrying loads will use a higher strength concrete. The strength is adjusted by adding or subtracting the percentages of the raw materials in the mix; limestone, water, sand, and mortar mix.
Do you vibrate lean concrete?
Yes, lean concrete can be vibrated to ensure proper compaction and eliminate air pockets. Vibrating helps achieve a denser and more uniform mix, which enhances the strength and durability of the concrete. However, care must be taken not to over-vibrate, as this can lead to segregation of the materials. It's essential to follow proper guidelines for vibration techniques and duration.
What steps should be taken to properly prep for a concrete slab installation?
To properly prep for a concrete slab installation, the following steps should be taken: Clear the area of any debris or vegetation. Compact the soil to create a stable base. Install a layer of gravel or sand for drainage and support. Set up formwork to define the shape and size of the slab. Place reinforcement such as rebar or wire mesh for added strength. Pour and level the concrete mixture evenly. Allow the concrete to cure and set properly before using the slab.
What is residue of cement?
Residue of cement refers to the solid material that remains after the hydration process of cement has taken place. This residue can affect strength and durability of the concrete and should be minimized through proper mixing and curing practices.
