8/14/2019 Bldg.Tech.1 - Materials In Building Constuction - Concrete

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8/14/2019 Bldg.Tech.1 - Materials In Building Constuction - Concrete

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8/14/2019 Bldg.Tech.1 - Materials In Building Constuction - Concrete

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8/14/2019 Bldg.Tech.1 - Materials In Building Constuction - Concrete

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Prepared by: ARCH. PAULO C. PINEDA I, uap Pamantasan Ng Lungsod Ng Maynila - COLLEGE OF ARCHITECTURE AND URBAN PLANNING

Building Technology 1 - MATERIALS IN BUILDING CONSTRUCTION

Surface application finishes for concrete consist of: Hardeners Color pigments Special aggregates Sealers Abrasive materials Waterproofing agents, andfillers and patchers

2. PROPORTIONING OF CONCRETEBriefly stated, the principles of proper proportioning are as follows:

a) Use good quality materials: Portland cement, water, and aggregate.b) Determine the strength of the concrete using the water-cement ratio. (The strength increases as the water-cement ratio decreases).c) Determine the consistency of the mix using the slump test using as dry a mix as practicable.d) Add correct proportions of aggregates to the cement and water as will give a mix of the desired consistency.e) Make a mix thats workable, not harsh.The strength of a workable concrete mix depends upon the water-cement ratio.

The economy of the mix depends upon the proper proportioning of the fine and coarse aggregates.

There are several methods of proportioning concrete:

2.1. Proportioning by arbitrary proportionsProportioning concrete by the arbitrary selection of the proportions is the oldest, the most commonly used, the most convenient and the least scientific method.

In this method, the aggregates are measured by loose volume, that is, its volume as it is thrown into a measuring box.

One sack of cement is taken as 1 cu.ft.

Enough water is used to give the desired consistency.

Common mixes expressed in proportions by volumes of cement to fine aggregate to coarse aggregate are as follows:

CONCRETE PROPORTIONS

Class AA 1 : 1.5 : 3 For concrete under water, retaining walls

Class A 1 : 2 : 4 For suspended slabs, beams, columns, arches, stairs, walls of 100mm (4) thickness

Class B 1 : 2.5 : 5 For walls thicker than 100mm (4), footings, steps, reinforced concrete slabs on fill.

Class C 1 : 3 : 6 For concrete plant boxes, and any non-critical concrete structures.

Class D 1 : 3.5 : 7 For mass concrete works.

8/14/2019 Bldg.Tech.1 - Materials In Building Constuction - Concrete

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