Concrete & Masonry

Cement Mixes

Typically, to make concrete, about 10 to 15 percent cement is used with 60 to 70 percent aggregates (sand, gravel, crushed stones) and 15 to 20 percent water. For aggregates, it is preferred that there is a variety of sizing in the materials.

Recycled (reusing) concrete

Crushed concrete can be re-used as an aggregate in new concrete.

Unreinforced or Minimally Reinforced Masonry

Many large unreinforced or minimally reinforced masonry buildings have heavy columns and beams but this alone might not be enough to withstand seismic forces.

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Masonry building in Bali

Learn about unreinforced masonry buildings and earthquakes with EERi's Unreinforced Masonry Building and Earthquakes Guide

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Minimally reinforced concrete structure in Palau Lombok

This type of housing can rapidly collapse due to partial or total failure of the columns or walls. The pressure of raising or passing water and the impact by floating debris makes this type of housing highly vulnerable.

When creating concrete pillars, columns, or walls, it is recommended that rebar (reinforcing steel) is incorporated as it makes concrete much stronger. Concrete is strong in compression (pushing toward center) but weak in tension (pulling away from center). The tensile capacity of concrete is only about 10% of the overall compressive strength. Steel reinforcement such as rebar, however, is strong in tension.

Reinforced Masonry

Below is an example of columns that have been sufficiently reinforced:

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See our Metals page to learn more about rebar and how it is used.

Resources to Review

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