Importance of Correct Proportion in Concrete Pastes

Concrete is widely used in the construction industry. To put it simply, it is a mixture of paste and aggregates. The paste is composed of cement and water and the aggregates used could both be fine and coarse or large in dimension. A chemical process called hydration helps the paste to harden and gain strength to metamorphose into a rock-like mass called concrete in course of time. Initially, that is when it is newly mixed the paste remains soft and malleable. Gradually, as it dries up it gets hardened and becomes immensely strong and durable. It is because of this peculiar property, it is conveniently used to construct bridges, skyscrapers, sidewalks, houses, dams and superhighways, etc.

Interestingly, concretes can exhibit different properties depending on its compositions. Mixing water to cement, chemical admixtures and aggregates leads to primary construction materials for buildings. These concrete and cement standards allow laboratories all over the world to conduct testing and evaluation of the concrete mixtures to verify their strength and safety. As such, cement aggregate concrete testing is a common phenomenon practiced across the construction industry.

The testing and evaluation procedure mentioned above proves helpful to identify various properties of concrete like strength, elasticity, hardness and functionality. Any seasoned professional involved with the building and construction industry knows the importance of right proportion for a concrete paste. A mixture that lacks enough paste to fill the voids between the aggregates proves difficult to place and comes up with rough surface and porous concrete. On the other hand, mixture having excess of cement paste is easy to place and comes up with smooth surface. However, it proves to be more costly and is prone to get cracked.

Thanks to the dedicated effort of construction materials testing company in Singapore, task has become less cumbersome and less complicated for project owners, contractors and technical experts associated to construction business. These testing entities depend largely on latest scientific breakthroughs and usually employ a string of scientists, engineers and other trained experts. These players undoubtedly provide impressive quality of service at much reasonable price.

Selecting the Right Aggregates for Concrete

All categories of concrete are prone to shrink. Shrinkage potential of a concrete mixture is perhaps one of the most crucial topics to consider while executing a construction project. Concrete shrinkage results in loss in volume, which in turn may facilitate cracking. The feature of concrete may also result in developing curling or warping issue. These problems diminish the load-carrying capacity of a structure and even lead to the problem of joint stability such as spalling. These unwanted factors usher in a potential health and safety issue. In order to overcome all these potential hazards, it is crucial to understand concrete shrinkage.

Concrete aggregates experience a change of volume because of factors like loss of moisture or decrease in temperature. Similar to most substances on earth, concrete has the tendency to expand and contract with change of temperature. If the surface of a concrete slab is cooler than the bottom, the concrete structure contracts resulting the slab edges to curl upward. Likewise, if the surface is allowed to dry and the bottom is kept moist, then the concrete slab warps upward.

However, to avoid this discrepancy, cement aggregate concrete test proves to be helpful. As such, the necessity of using the right type and quality of aggregates in construction projects is paramount. The fine and coarse aggregates usually occupy 60 to 75 per cent of the concrete volume. Moreover, these ingredients strongly influence the concrete’s hardened properties. Fine aggregates usually consist of naturally found sand or crushed stone.

Some natural aggregate deposits also consist of gravel and sand that can be readily used in concrete after conducting a minimal processing. This variety of aggregate deposits is known as pit-run gravel. Natural gravel and sand is scoured from river or seabed. Chips of stone are produced by crushing quarry rock, boulders, cobbles or even large-size gravels. There is no second opinion about maintaining certain standards for aggregates. Apart from being clean, these must be hard and strong and should not contain any absorbed chemical. Moreover, these particles should contain adequate amount of clay or other fine material to facilitate hydration and bond of the cement paste.