How do you reduce the weight of concrete?
Lightweight concrete is made by replacing some (or all) of the normal weight aggregate (crushed limestone, granite, quartz, etc.) with a lightweight aggregate (expanded clay, shale or slate) to reduce the overall weight of the piece.
What is meant by mass concrete?
Mass concrete is defined by the American Concrete Institute as: “any volume of concrete in which a combination of dimensions of the member being cast, the boundary conditions, the characteristics of the concrete mixture, and the ambient conditions can lead to undesirable thermal stresses, cracking, deleterious chemical …
How do you lighten concrete weight?
Using less sand can make the product lighter, but it can also make the concrete weaker structurally. A simple recipe for basic lightweight concrete is to combine 8 parts sand, 8 parts cement and 8 parts perlite to 5 parts water.
What is the thickness of mass concrete?
Mass Concrete: When It Applies Although no specific thickness is given, a member thickness of three feet is often used as the threshold dimension for when mass concreting procedures are to be set in motion.
What is normal weight concrete?
As mentioned earlier, normal concrete can weigh between 140 to 150 Lbs/ft³ due to the presence of denser aggregates in their natural state.
When can I remove formworks?
between 24 hours and 72 hours
Formwork should only be removed when the underlying concrete is strong enough to support its own weight and loads placed on it. This is usually between 24 hours and 72 hours, depending on the type of concrete project. Some formwork is designed to be permanent.
Where is mass concrete used?
Mass concrete is usually associated with large, poured in-situ concrete structures such as dams, bridge piers, foundations to very tall buildings and other large volume placements which are at least 1m-deep. In many cases, mass concrete is unreinforced and therefore strong in compression but weak in tension.
What is the grade of mass concrete?
Different types of concrete grades and their uses
| Concrete Grade | Mix Ratio (cement : sand : aggregates) | Compressive Strength |
|---|---|---|
| M10 | 1 : 3 : 6 | 1450 psi |
| M15 | 1 : 2 : 4 | 2175 psi |
| M20 | 1 : 1.5 : 3 | 2900 psi |
| Standard Grade of Concrete |
How much does light weight concrete weigh?
With a standard thickness of 1.5 inches, normal weight concrete weighs about 18 lbs per square foot while lightweight concrete weighs 14.5 lbs per square foot.
What are the advantages of reducing the W C ratio?
Advantages of Low Water-Cement Ratio Reduced drying shrinkage and cracking. Less volume change from wetting and drying. Lower permeability. Creates better bond between concrete and reinforcement.
How long is concrete workable?
Under normal conditions, concrete has a useable life of about 11⁄2 hours. However in summer it will lose workability more rapidly. Ideally, it should be placed and completely finished within 1 hour of discharge from the truck-mixer.
How heavy is 1m3 of concrete?
One cubic metre of concrete weighs 2.5 Tonnes. Typically, 1m3 of concrete is made up of 350Kg of cement, 700Kg of sand, 1,200Kg of chippings and 150 Litres of water.
What should I Change my concrete mix for mass concreting?
Many recommended changes to the concrete mix for mass concreting reduce or slow the heat of hydration to limit temperature change and thereby lower the amount of crack formation. It is critical to reduce the quantity of cement in the mix.
What are the main concerns with mass concreting?
Another core concern with mass concreting is the potential formation of cold joints in the element. This is a problem more common to building structures as the use of higher strength concretes will rapidly accelerate the setting time of the concrete. Nighttime foundation mat placement with multiple points of placement.
What makes mass concrete different from other concrete?
ACI 207.1R states that the only characteristic that distinguishes mass concrete from other concrete work is thermal behavior that may cause a loss of structural integrity and monolithic action.
What happens when you reduce the amount of water in concrete?
Many important characteristics of concrete are influenced by the ratio (by weight) of water to cementitious materials (w/cm) used in the mixture. By reducing the amount of water, the cement paste will have higher density, which results in higher paste quality.