Author: Bruce Raath

What do water striders and concrete cracking have in common?

What do water striders and concrete cracking have in common?

Why does the surface of the water in a glass curl up at the edges and form a meniscus? The truth is, the water wants to escape but is held back by gravity. In a small diameter glass tube, the water will rise much higher because there is less water and gravity does not exert such an influence. The water has little attraction to the air above it and the effect is known as capillary attraction. [rml_... »

Why do we drill concrete cores?

Why do we drill concrete cores?

Assessment of concrete strength has traditionally been done by making and crushing of concrete cubes. This test gives little information regarding the strength of the concrete in the structure never specified. The strength specified on a drawing or a [rml_read_more] project specification is a cube strength which cannot consider any poor workmanship by the contractor, e.g. poor compaction, loss of ... »

Creative Minds Converge in Kenya

Creative Minds Converge in Kenya

I was indeed fortunate to be invited to attend a conference in Nairobi Kenya on the subject of “Innovation – Science – Engineering – Education.”  The famous quote from Nelson Mandela “Education is the most powerful weapon which you can use to change the world” was used in the context of Construction, to introduce a paradigm shift necessary in engineering education to make engineers more aware of e... »

Is concrete cracking the result of shrinkage only?

Is concrete cracking the result of shrinkage only?

Take a hypothetical example of a rugby pitch (or soccer if you prefer). Bring in a sheet of glass the same size as the pitch by using at least four powerful helicopters and place it on the grass. Raid the kitchen cupboard for the “Spray and Cook” and spray the surface of the glass. »

How much water is enough for Concrete workability?

How much water is enough for Concrete workability?

Take two buckets with a capacity of about 10 ℓ each. Fill one bucket to the top with marbles with a diameter of approximately 10 mm and the other with marbles about 25 mm diameter. Fill each bucket of marbles with water to the brim. Which bucket will take the most water to fill? »

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