Can cement be waterproof / 水泥可以防水吗

Can cement be waterproof?

A friend came to visit yesterday,
He intends doing waterproof by himself,
He went to see the penetrating water repellent and said there are many models, and asked me which one should I buy?

I don't know this, because I have used the waterproofing agent before, I have forgotten its brand, and it has been for so many years.

We Suddenly talked about cement,
My friend asked if I could use cement + water, that is, cement water for waterproofing?
Because he thinks that cement will harden when exposed to water, should it also be can waterproof?

His thought reminded me decades ago.

There was no waterproofing agent at that time,
We are use cement for waterproofing,
but the effect is not good.

And has very high requirements for the quality of construction,
And need do it many times.

Now doing waterproof,
Use professional waterproof materials,
As long as the construction is 3 times,
Base coat + middle coat + top coat,
Construction is divided into 3 times.

And the cement waterproof in the past,
It doesn't mean using cement,
Refers to the use of cement mortar for waterproofing,
Cement + sand + water must be constructed in a certain proportion,
There are requirements for the composition of the material, and the ratio must be correct will to use it.

Therefore, cement mortar waterproofing has very high requirements for the quality of construction, including post-construction maintenance. It should be no one in modern times.
It's too much work, and it may not be done well.

If it leaks,
Brush cement water, that is, cement + water, it will be completed after brushing dozens of times.
The cement water will be sucked in, and after hardening, it achieves the waterproof effect.

But the time limit for this effect is very short,
Because after the cement hardens, it rains,
Soaked in rain for a long time,
The cement block will slowly spit white,
That is, some of the ingredients inside will be diluted by water,
The strength of cement will gradually deteriorate,
Finally, the whole is broken.

The hardness of the cement block is not very large,
When encountering water or acid,
Will melt away, that is, vomit white.

Spit white is the white powder seen on the wall,
That is the cement in concrete or cement mortar,
After encountering water, vomited out.

Therefore, cement will harden when exposed to water, that is the initial stage,
When it hardens, it will dissolve when exposed to water, and part of the substance inside will slowly spit out, commonly known as vomiting.

Cement is mainly made of two materials, clay and limestone, which are fired at high temperatures and mixed in a certain proportion.