La muratura deve essere rinforzata.

Because muratura is a feminine singular noun in Italian, so it takes the feminine singular definite article la.

This is just a property of the noun itself; grammatical gender in Italian does not always match anything logical in English. You simply learn la muratura as the normal form.

Because the subject is la muratura, which is grammatically singular.

So the verb dovere must also be singular:

• la muratura deve = the masonry must
• le murature devono = the masonry structures / the walls must

Even if muratura refers to a large structure, it is still grammatically singular here.

Because this sentence is in the passive voice.

• deve rinforzare = must reinforce
  This would need an agent, someone or something doing the reinforcing.
• deve essere rinforzata = must be reinforced
  This focuses on what needs to happen to the masonry, not on who does it.

So the structure is:

• deve = must
• essere = be
• rinforzata = reinforced

This is the normal way to form a passive construction with a modal verb in Italian.

Because in a passive construction with essere, the past participle agrees with the subject in gender and number.

Here the subject is la muratura, which is feminine singular, so we get:

• masculine singular: rinforzato
• feminine singular: rinforzata
• masculine plural: rinforzati
• feminine plural: rinforzate

Since muratura is feminine singular, rinforzata is the correct form.

Grammatically, it is the past participle of rinforzare.

In this sentence, it is being used as part of the passive verb phrase:

• essere rinforzata = to be reinforced

Past participles in Italian often behave a bit like adjectives because they agree in gender and number, but here its main role is verbal, not just descriptive.

Yes, but it is less direct and can sound less natural depending on context.

A more standard way to keep the same meaning would be:

• La muratura deve essere rinforzata

You may also hear:

• Si deve rinforzare la muratura = The masonry must be reinforced / One must reinforce the masonry

That version uses si impersonale/passivante and is very common in technical or formal language. It shifts the structure slightly, but the overall meaning is similar.

Yes. That is a very common alternative, especially in technical, practical, or written contexts.

• La muratura deve essere rinforzata = The masonry must be reinforced
• La muratura va rinforzata = The masonry needs to be reinforced / should be reinforced

Va + past participle is often used in Italian to express necessity in a concise way. It is very natural in instructions, reports, and technical descriptions.

Because the sentence does not mention the agent.

Italian, like English, often uses the passive when the important thing is the action or necessity, not who performs it.

So:

• La muratura deve essere rinforzata = The masonry must be reinforced

If you wanted to add the agent, you could say:

• La muratura deve essere rinforzata dagli operai = The masonry must be reinforced by the workers

But very often that extra information is unnecessary.

Usually it expresses necessity or requirement.

In a sentence like this, especially in a technical or construction context, deve usually sounds fairly strong:

• it is required
• it is necessary
• it needs to be done

So it is usually stronger than a mere suggestion.

Sometimes, depending on context, but not always exactly.

Muratura usually refers to masonry, brickwork, or a masonry structure/wall construction, rather than just a simple everyday wall.

So although English may sometimes translate it as wall in context, the Italian word is often a bit more technical and refers to the material or type of construction.

The infinitive is rinforzare, meaning to reinforce.

Here is the chain:

• rinforzare = infinitive
• rinforzato / rinforzata / rinforzati / rinforzate = past participle forms agreeing with gender and number

So in this sentence:

• deve essere rinforzata = must be reinforced

The normal word order is:

• La muratura deve essere rinforzata

That is the most natural and neutral order.

Italian does allow some flexibility for emphasis, but in an ordinary statement, especially a technical one, this standard order is best. An English speaker should generally stick to this pattern unless there is a specific reason to emphasize something.