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Canal Comes Alive with Lighted Boat Parade.

Types and Causes of Cracks in Concrete

One of the major causes of cracks in concrete is contraction and cooling due to heat evolution during the process of hydration which leads the concrete towards the setting. Cracks can appear in the section which is smaller and attached to the larger section due to differential expansion and contraction. The rapid drying usually occurs during hot weather when concrete

Concrete Accelerators - Definition, Examples and Effects

Accelerating Admixture - an admixture that causes an increase in the rate of hydration of the hydraulic cement and thus shortens the time of setting, increases the rate of strength development, or both. Accelerating admixtures are added to concrete either to increase the rate of early strength development or to shorten the time of setting, or both. Chemical

Concrete Basic Properties & Concepts

Concrete is made by mixing: Cement, water, course fine aggregates and admixtures (if required). The aim is to mix these materials in measured amounts to make concrete that is easy to: Transport, place, compact, finish and which will set, and harden, to give a strong and durable product. A concrete mix is designed to produce concrete that can be easily placed at the

Properties of Fresh Concrete

Fresh concrete is that stage of concrete in which concrete can be moulded and it is in plastic state. This is also called "Green Concrete". Another term used to describe the state of fresh concrete is consistence, which is the ease with which concrete will flow. The transition process of changing of concrete from plastic state to hardened state. Setting of concrete is

Properties of Hardened Concrete

It is mainly due to the binding properties of cement that the ingredients are compacted together. If the paste has higher binding strength, higher will be strength of concrete. It is mainly the aggregate that provide strength to concrete especially coarse aggregates which act just like bones in the body. Rough and angular aggregate provides better bonding and

Batching, Mixing, Placing and Compaction of Concrete

Is the process of measuring concrete mix ingredients either by volume or by mass and introducing them into the mixture. Traditionally batching is done by volume but most specifications require that batching be done by mass rather than volume. Percentage of accuracy for measurement of concrete materials as follows. When the quantity of cement to

Tests on Concrete

SAMPLING 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

ACI Method Concrete Mix Design & Mix Ratio

Mix design can be defined as the process of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing concrete of certain minimum strength and durability as economically as possible. One of the ultimate aims of studying the various properties of the materials of concrete, plastic concrete and hardened concrete is to

Planning & Site Preparation for Concrete

The most important step in placing concrete is planning. Always plan every step before any concrete is delivered. Proper planning avoids delays, wastage, segregation and problems which develop from these. Proper concrete planning also eliminates problems of Delay, Segregation and Wastage. Workers on the site should always wear protective clothing, strong boots and

Admixtures of Concrete & Cement

A material other than water, aggregates, or cement that is used as an ingredient of concrete or mortar to control setting and early hardening, workability, or to provide additional cementing properties. Admixtures are generally used to alter the properties of concrete (such as increased workability or reduced water content, acceleration or retardation of setting time,

Types and Uses of Special Concrete

Special Concrete means the concrete used or made for special cases, such as: Frequently, concrete may be used for some special purpose for which special properties are more important than those commonly considered. Sometimes, it may be of great importance to enhance one of the ordinary properties. These special applications often become apparent as new

Hot Weather Concreting

ACI 305 “Hot Weather Concreting” defines hot weathers as any combination of the following conditions that tends to impair the quality of the freshly mixed or hardened concrete: The success of many hot-weather concreting operations depends on the steps taken to slow the cement hydration reactions within the concrete and to minimize the rate of evaporation of

Cold Weather Concreting ACI 306

ACI 306 “Cold Weather Concreting” defines cold weather concreting as a period when for more than three (3) consecutive days, the following conditions exist: The average daily air temperature is less than 5°C (40°F) and, The air temperature is not greater than 10°C (50°F) for more than one-half of any 24 hour period. ete placed during cold weather will develop

Creep in Concrete

Concrete creep is defined as: deformation of structure under sustained load. Basically, long term pressure or stress on concrete can make it change shape. This deformation usually occurs in the direction the force is being applied. Like a concrete column getting more compressed, or a beam bending. Creep does not necessarily cause concrete to fail or break apart. Creep

Definition and Types of Concrete Shrinkage

Concrete is subjected to changes in volume either autogenous or induced. Volume change is one of the most detrimental properties of concrete, which affects the long-term strength and durability. To the practical engineer, the aspect of volume change in concrete is important from the point of view that it causes unsightly cracks in concrete. We have discussed elsewhere the

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