"Cement and Asphalt" Highway PPT Courseware

Description

"Cement and Asphalt" Highway PPT Courseware

What do you know about cement and asphalt?

Take a guess

What happens when you add a small amount of water to cement?

Changes in cement

30 seconds after mixing

The cement turns dark gray in color, becomes fluid, and emits an earthy smell. The beaker is slightly warm

2 minutes after mixing

The cement turns dark gray in color, becomes fluid, and emits an earthy smell. The beaker is slightly warm

5 minutes after mixing

The cement is divided into two layers, the upper and lower layers. The color changes to dark gray, is fluid, and emits an earthy smell. The beaker is slightly warm

after one day

The cement turns light gray and condenses into hard blocks with a shiny surface. no smell

After the cement is added with water and dried, it turns into a hard block and cannot return to the original powdery cement. This is an irreversible change process. In this process, new substances are formed in the cement.

think about it

Irreversible changes have occurred after adding water to the cement. So what will happen to the asphalt when it is heated? What happens after it cools down?

I find:

After solid asphalt is heated, it will change its original shape and form a flowable liquid. When the temperature is lowered, it will change back to its original state. This is a reversible change process.

During this process, no new substances are formed in the asphalt.

summary

Changes in substances are divided into two categories: one is just a change in form, such as salt and sugar dissolving in water; the other is a change that produces new substances at the same time, such as cooking, burning firewood, etc.

Keywords: highway teaching courseware, cement and asphalt teaching courseware, E-education version fifth grade science PPT courseware download, fifth grade science slide courseware download, highway PPT courseware download, cement and asphalt PPT courseware download, .PPT format;

For more information about the "Highway Cement and Asphalt" PPT courseware, please click the Highway ppt Cement and Asphalt ppt tab.

"Cement and Asphalt" Highway PPT Courseware 3:

"Cement and Asphalt" Highway PPT Courseware 3 What we just saw is the picture of building roads and bridges. Students, think about it, what materials are usually used to build roads and bridges? Cement, asphalt, steel, etc. Learning objectives 1. I know that some changes in matter are reversible and some are irreversible..

"Cement and Asphalt" Highway PPT Courseware 2:

"Cement and Asphalt" Highway PPT Courseware 2 Cement and asphalt are often used in paving roads and building bridges. What do we know about cement and asphalt? Guess what happens when you add a small amount of water to cement? Experimental tips: 1. Don’t add too much water, but do it in batches.

File Info

Update Time: 2024-11-22

This template belongs to science courseware E-education edition fifth grade science volume 1 industry PPT template

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