Details about R-value and U-value of Concrete Slab

The conduction of heat regarding the materials utilized in its construction is measured with the thermal conductivity coefficient alias k-value (W/m.K), of the materials used in its construction. It belongs to the rate at which heat moves through a material among points at dissimilar temperatures.

The thermal resistance alias R-value (m2K/W), is computed by dividing the thickness of the material (in metres) with the k-value. From this the thermal transmittance alias U-value (W/m2.K) concerning a building material is measured like the inverse of the sum of the R-values of the component parts and adjoining air layers.

R-value stands for the estimation of concrete slab (or other material) strength to counter heat flow i.e. it calculates the potency of insulation or thermal resistance. However, U-value stands for the estimation of heat transmission throughout concrete slab from ground into the closed space or oppositely.

Since, thermal insulation fluctuates contrariwise with density, lower density concrete offers superior insulation as compared to greater density concrete. With the purpose of determining the strength of the reinforced concrete slab to withstand heat transfer, it is necessary to estimate R-value and U-value of the reinforced concrete slab under consideration.

The method for estimating R-value for Concrete Slab: A perfect R-value for a normal concrete slab is computed with an R-value, the thermal resistance per inch of thickness, among 0.1 and 0.2 and multiplying it times the slab thickness. The value of R is determined with the following equation provided by ASTM C 168:

Here, the temperature variation (among exterior and interior of concrete slab) is provided in degrees Fahrenheit, the area is given in square feet, the time in hours, and the heat loss in Btus.

ASTM C 168 also offers two supplementary expressions to measure R-value and is available in ASTM C 168 document.

The R-value imperial unit and metric unit are given below:

Computation of u-value for Concrete Slab

The U-value for a concrete slab (and any other building material) stands for the inverse of its R-value and is computed with the formula given below:

The U-value unit is the inverse those of R-value:

Note: There is difference among the American Standard and European Standard for R-value and U-value. Therefore, to transform an American R-value into a European U-value, divide 1 with the R-value, then multiply the result by 5.682 whereas transforming a European U-value to an American R-value, multiply with 0.176, then divide 1 by the result.



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Published By
Rajib Dey
www.constructioncost.co
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Benefits of developing precast concrete homes

Precast Concrete Homes is now considered as a very popular construction method all through the globe as they are exceedingly solid and durable. Various precast concrete panels are used to develop a building. It is possible to build a standard 4 bedroom home just in 8 weeks. Any building can be constructed 16 weeks quicker as compared to brick veneer. This construction method facilitates the builders to complete more homes in each year.

Precast Concrete Homes are formed with the concrete walls which offer superior thermal and acoustic insulation to make the home stronger. They contain good resistance capacity to cyclones, floods, earthquakes and ground movements. Besides, they are also mold and mildew resistant related to a customary wood or brick home. They are also very useful for bushfire prone areas because they surpass the Australian Bushfire Standard (AS3959) for the utmost “Flame Zone” category.

Total precast homes contain no beams and columns in the basement which offers stretched clear spans for a very flexible design. Precast floors are very useful if they are amalgamated with radiant heat.

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Published By

Rajib Dey

www.constructioncost.co

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How to Build Disaster Resistant Home

The Precise Aluminum Forming System has been utilized very effectively for concrete homes, apartments, warehouses, prisons, as well as in the earth sheltered industry due to the systems versatility and ease of use. Almost any style home can be built out of concrete, including multistory home.

The Precise Concrete Forms will enable you to form and pour the walls, beams, columns, deck, and roof in one continuous pour per level. The window and door openings are cast in place simultaneously with the walls and ceilings. With the rising amount of severe weather, all concrete structures are a definite alternative. The modular design of the Precise System permits unlimited configurations and architectural designs. Precise forms are available in the attractive smooth finish or our popular brick patterns. A pitched ledger is available for homes with a pitched roof.

The Precise Forming System is simple to operate. Few tools are required and unskilled laborers are easily trained. Developers are setting and pouring a unit a day. Entire subdivisions have been built using the Precise Forming System.

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Published By

Rajib Dey

www.saudiarabia.quantity-takeoff.com

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