What is slump in concrete

 

Slump is vertical settlement of the concrete after the mould has been withdrawn and the vertical difference between height of mould and the highest point of subsided concrete.

Following slump test apparatus is used to do slump test.

The apparatus for determining the slump includes following items 

1- Slump Cone ( Steel mould in form of a truncated cone).

2- Tamping Rod (Is used to tamp the slump cone and for Roding of concrete

3-Measuring Tape (measure vertical displacement of concrete after removal of cone)

4-Smooth Surface Sheet (Provides smooth surface to keep slump cone vertical).

5-Trowel. (Used to Fill the concrete in cone).

6-Hand Level (after removal of cone Hand level is placed horizontally over the Slump cone to measure vertical displacement of concrete.)

Testing Procedure

Place the slump cone on leveled sheet and fill the cone with concrete in 3" consecutive layers with Roding to compact concrete until it fills up to the top of cone. During filling of concrete cone should be in hold with placing of feet on lower pedestals and may be lifted above holding the hooks fixed in the middle of the cone. Now after removal of cone place the cone near settled concrete and place the hand level on the top of cone extending up to the top of concrete and then measure vertical displacement with measuring tape.

What should be the slump of concrete.

Although the slump test is not entirely satisfactory since it gives widely varying results and also does not give a true measure of workability but it is of value in the field as a control test and is useful in comparing the consistence of successive batches of concrete made with the same ingredients ,and is one of the simplest tests to carry out at site. Provided no change is made in the aggregate or it's grading ,slump tests will indicate whether correct water and cement contents are being maintained. For a given slump  and aggregate grading, water required for the unit volume of concrete is constant irrespective of the change of the cement content.

The amount of the slump depends not only on the amount of water in the mix but also on the nature of aggregates ; rounded stones give a greater slump than angular stones for the same mixture.  

Recommended values for slump in Millimeters.
S No	Types of Work	With Vibrations	Without Vibrations
1	Mass Concrete, Large sections, roads	10 to 25	50 to 75
2	Foundations ,Footings ,Sub-Structures, Walls and other heavy sections.	26 to 50	40 to 115
3	Thin Sections such as slabs ,columns, beams with congested reinforcements	40 to 80	100 to 175

 

How slump is recommended ?

This is very important to understand about the practical recommendations of slump and here is the details which includes Selections of materials and proceeding with job mix formula with number of hit and trial tests to obtained required strength of concrete. During each test of job mix slump test has been conducted and recorded in laboratory and when that slump is recommended on which designed strength of concrete has been obtained.  

Types of Slump

There are three types of Slumps .

True slump refers to common drop of the concrete mass evenly all around without collapse.

Shear slump indicates that the concrete lacks cohesion. It may undergo segregation and bleeding and thus is undesirable for the durability of concrete.

Collapse slump indicates that concrete mix is too wet and the mix is regarded as harsh and lean.

This Blog contains supporting images which are property of Google only.

Effect of water-cement ratio on strength of concrete

 

The workability of concrete increases as water content of mix increased, water lubricates the mixture of concrete. But increase in water content causes the decrease in strength of concrete .Excessive use water weakens the concrete ,produces shrinkage cracks and decreases density of concrete.

 Water occupies the space in concrete and as it evaporates it leaves voids and cracks which decrease the strength of concrete. The volume of water voids may be as much as 10 percent of the total volume of concrete. An excess of 10 percent of water may reduce the strength by about 15 percent and an excess of 30 percent of water may reduce the strength up to 50 %. Lower the water content the stronger the concrete but quantity of water must be sufficient to produce a workable mix required for particular method of compaction to be adopted for concreting.

Concrete made with low water cement ratio is unworkable. If stiff or dry concrete is used then honey-combing will result decrease in density and strength. An unworkable concrete results in incomplete compaction giving rise to air voids. If 5% Air voids exists in concrete may cause 30 % strength loss and 10 % air voids may cause as much as 50 percent strength loss.

Water Cement Ratios Adopted for different mix of Concretes.
S No	CONCRETE MIX	WATER CEMENT RATIO	QUANTITY OF WATER IN LITERS	REMARKS
1	(1:1:2)	0.42 TO .54	21 TO 27	For vibrated concrete ,the quantity of water may be reduced by about 20 %
2	(1:1.5:3)	0.52 TO 0.60	26 TO 30
3	(1:2:4)	0.58 TO 0.64	29 TO 32
4	(1:3:6)	0.68 TO 0.72	34 TO 36
5	(1:4:8)	0.90 TO 0.94	45 TO 47

Therefore there is an optimum value of water cement ratio for every mix which should only be decided after properly adopting of job mix formula, and water content has to be restricted within certain minimum limits. Concrete should be plastic to be worked around the reinforcement rods.

Sometime strength has to be sacrificed by adding more water to obtain higher degree of workability where concrete has to be placed in narrow and thin RCC sections.
The best mix is the one which gives the maximum workability with minimum amount of water .An increase in water content must be accompanied by proportionate increase of cement if strength is to be maintained.

Hydration of cement is incomplete without an adequate quantity of water, Less water impedes complete setting of cement and decreases the strength of concrete. The amount of water required to complete the hydration of cement is about 25 % of the weight of the cement.
Generally the water cement ratio for Concrete (1:2:4) mix is 0.60 ,Concrete (1:1.5:3) mix is 0.50 and for concrete mix (1:1:2) mix is 0.45.  

Water Cement Ratio Formula

 

The Ratio between weight of water and weight of cement is called water cement ratio.

Formula of water cement ratio is given below

WCR =  W/C

Water Cement Ratio = Weight of Water / Weight of cement

Water cement ratio is mathematical expression having no units but it can be expressed in percentage for example if we find WCR =.6 using job mix formula ,the amount of water may be calculated from formula as below.

 WCR =  W/C

Water Cement Ratio = Weight of Water / Weight of cement---------Eq.no.1

Putting Values in Eq.no.1 considering Weight of One bag of cement.

 0.6= (Weight of water /50 Kgs)

Weight of water = 0.6 x 50 Kgs = 30-Kgs

Here we knows that 1Kg = 1 Liter

So we can say according to designed WCR 30-Liters or 30-Kgs of water will be added to concrete mix.

WCR is designed formula for use of water in concrete mix with respect of weight of cement and it is very important for workability and strength of concrete. More water in concrete improves workability (Ease in concreting) of concrete but on other hand it decreases the strength of concrete.  

Roughly Water Cement Ratio for Concrete (1:2:4)  = 0.60

                                                  Concrete (1:1.5:3)  = 0.50

                                                     Concrete (1:1:2)  = 0.45

This Blog contains supporting images which are property of Google only.

Exercises to lose weight fast at home

 There are several exercises to lose weight if doing on quotidian routine. Listing some exercises to lose weight fast and which are as follows.

1- Walking.

When you want to lose weight, Multiple experts suggest quick walking as a calorie­ burning cardio exercise. But what's the right quantum of walking each day to help you achieve your weight loss it depends on weight and age of person. Try not to skip farther than one day in a row. Thickness is good for burning calories and helping your metabolism, as well as for making new habits. On your non ­walking days, try strength training exercises. However, take a day off, If you find yourself worn out. But be sure to get back walking the following day. Notwithstanding, the Experts recommends you should spend 60 to 90 nanoseconds most days of the week in moderate­ intensity physical exercise while not eating farther calories than you expend all day, If you've hit your weight loss mark and are working on maintaining your weight. At a fast walking speed, you would burn 100 to 300 calories in 30 nanoseconds ( depending on your weight) or 200 to 600 calories in an hour. By walking for 30 nanoseconds or farther at a time, some of those calories will be from stored fat. During the first 30 nanoseconds of exercise, your body is burning sugars stored as power. These are used up after about 30 nanoseconds. To keep going, your body releases fat from your fat cells and burns it for energy. This stored fat is exactly what you want to lose, and it's a good reason to construct up your walking ceaselessness so you can walk for additional than 30 flashes at a time. 

2- Running.

Running is a casual preference, as it burns fresh calories requires multiplex  different muscles to work hard together.

In particular, high- intensity interval training involving running streamlets the most calories per second by using prismatic muscles at their maximum power.  

Multiplex studies have exposed that running increases run. This has led to the hourly- repeated watching “ If exercise were a lozenge, it would be the most popular lozenge in the world. ” Worth noting It would also be the least priceless, with little to no cost.

 3-Cycling

Stable, modest cycling burns about 300 calories in 60 flashes, but you can burn additional than that if you increase the intensity. In fact, according to the Harvard Health Letter, a 155-pound person can burn as beaucoup as 298 calories in a 30- flash bike lift, if they pedal at a 12-to-13.9 afar-per-hour pace.

4- Swimming

Swimming is an competent way to burn calories. A 73-KGs person burns much 423 calories an hour while swimming legs at a low or moderate pace.  

That same person may burn up to 585 calories an hour swimming at a additional vigorous pace.

5-Weight training

Weight training is an crucial a part in case you're new to weight schooling, don't forget operating with a health specialist or trainer to examine right shape and approach to assist keep away from the hazard of harm and get the most blessings.

Heat up with 5 to 10 mins of stretching or brisk walking. Then pick out a weight or resistance stage heavy sufficient to tire your muscle tissue after 12 to 15 repetitions.  

With the right weight,a unmarried set of 12 to 15 repetitions can construct muscle successfully in the majority and may be as powerful as more than one units of the same workout,to give your muscle tissues time to recover, relaxation one complete day among exercising every unique muscle group, and don't forget to complement weight schooling sporting activities with aerobic hobby. 

 

The department of fitness and Human offerings recommends incorporating  energy education physical games of all of the primary muscle companies into a health routine as a minimum two instances a week while getting at the least 150 minutes of mild cardio interest or seventy  five minutes of vigorous cardio interest per week, or a combination of moderate and energetic activity

Chest press

The chest press is an exercise you may do with dumbbells to bolster the pectoral muscular tissues in the the the front of your chest, a number of the shoulder muscle groups and the triceps muscles in the again of your higher palms.
misinform your lower lower back together along with your knees bent and a dumbbell in every hand. keep your top fingers perpendicular for your frame and maintain your forearms perpendicular to the ground. Slowly press the weights upward till your elbows are almost immediately. Be careful to keep away from locking your elbows right right into a immediately function.
you may feel anxiety at some stage in your top chest. move returned to the start position slowly, being careful not to drop your elbows underneath the surface of the bench. Repeat.
even though the chest press is normally finished mendacity on a weight bench, you may additionally strive it mendacity at the floor.

Bent-over row with dumbbell

The bent-over row is an exercising you can do with a dumbbell to reinforce the muscle tissues for your top again and the again of your shoulder.
begin with one knee resting on a weight bench. Lean forward, helping yourself together with your hand. preserve a dumbbell on your other hand, letting your arm cling immediately underneath your shoulder. Slowly raise the load until your elbow strains up just below your shoulder.
you may feel tension in the lower back of your shoulder and the muscular tissues throughout your upper back. Then slowly lower the load to the beginning function. Repeat.
you can additionally do the bent-over row with out a weight bench. Stand along with your toes effectively apart. Then bend your knees and lean forward at the hips.

Triceps extension

 The triceps extension is an workout you could do with a dumbbell to reinforce the triceps muscle within the back of your top arm.

Lie in your back with a dumbbell to your hand. factor your higher arm towards the ceiling, along with your elbow bent to ninety degrees. Slowly straighten your elbow, shifting the burden upward. keep away from the use of momentum to force your elbow directly.
you may sense tension in the muscles in the returned of your top arm. Then slowly decrease the weight to the beginning role. Repeat. If important, use the other hand to help hold your arm in a 90-degree role during every extension.
you can do triceps extensions lying on a weight bench or on the floor.

Biceps curl with dumbbell

The biceps curl is an exercising you may do with a dumbbell to strengthen the biceps muscle within the front of your top arm.
Rise up straight with your toes approximately shoulder-width apart and your knees slightly bent. hold the dumbbell with your palm dealing with upward. Slowly curl the load up by bending your elbow, keeping your elbow near your frame.

Then slowly decrease the burden to the starting role. you'll experience tension within the muscle groups inside the front of your higher arm. Repeat. For nice results, do not swing your arm or elbow,keep your wrist instantly and inflexible.

For a center and balance venture, paintings each biceps on the identical time via alternating fingers at some stage in the exercise.

Knee extension

The knee extension is an exercise you may do with an ankle weight to bolster the quadriceps muscle in the the front of your thigh.
secure an ankle weight in your ankle. Then take a seat on a chair or weight bench, together with your ft dangling in a at ease function. Slowly straighten your knee, pause after which return to the starting function. Repeat. hold your moves smooth and managed, and be careful not to snap or lock your knee into extension.
you could do the identical workout with a knee extension system.

Pushup

Weight education includes physical activities that use your own frame weight for resistance. The pushup, as an instance, strengthens the pectoral muscle mass inside the the front of your chest, the shoulder muscles and the triceps muscle mass in the again of your top hands.
position yourself in your palms and feet with your eyes facing the floor. vicinity your fingers slightly greater than shoulder width apart and your feet comfortably apart. 

Slowly bend your elbows and lower your chest till your chin reaches the floor.

you may experience tension inside the muscles in your again, abdomen and higher fingers. Then slowly go back to the starting position. 

Repeat If a pushup is tough so that you can do, strive a modified pushup. in this exercising, perform a pushup while keeping your knees at the ground.

whilst you're doing pushups, be careful no longer to allow your again or hips sag down or arch up. maintain your moves clean and managed.

Squat

The squat is a body resistance workout that strengthens several muscular tissues, consisting of the quadriceps muscle tissue within the front of your thighs and the hamstring muscle tissues in the returned of your thighs.
Stand along with your feet barely more than shoulder-width apart and your feet pointing in advance. Slowly descend, bending thru the hips, knees and ankles. keep your again in a impartial role, and do not allow your knees roll inward or outward.
Stop when your knees reach a ninety-degree perspective. you'll feel tension in your legs and buttocks. Then return to the beginning role. Repeat. in case you cannot bend your knees to a ninety-diploma angle, sincerely pass as little as you could.
For a greater challenge, keep dumbbells at your sides with your hands facing your frame whilst you squat.

  Pilates.

Pilates aims to make stronger the body in an even way, with particular emphasis on core strength to improve general fitness and wellbeing.

This Blog contains supporting images which are property of Google only.