The answer to that question is tricky. The true answer is: Well, yes and no. It all depends on what you mean by “cleaning.” If you want to get rid of just some surface dirt, a sweeping or leaf blowing will do the job. If you want to get a deeper level of cleaning, more in-depth techniques have to be used. If old motor oil or rust stains have penetrated deeply into the pavers, still more advanced techniques have to be brought in.
First, you have to access the level of cleaning needed. For light organic dirt, a power washing may suffice. However, bear in mind that unsealed pavers are porous by nature, and liquids penetrate deep into the pores. When the liquid evaporates it leaves behind the solids. Something as simple as rain, over time, will carry grime and dirt deep into the pores. Removing all the grime usually requires specific cleaning agents, with proper application equipment.
For deeper and stubborn stains, power washing alone may not do the job correctly. While a power washer cleans the surface, it will not dissolve out the solids. For example, if a leaky car was parked on the pavers, old motor oil sank deep into the pores. Removing the oil may involve steam cleaning along with specialized surfactants designed just for hard stains.
One aspect to consider is the environmental concerns of the cleaning agents themselves. You may try muriatic (hydrochloric) acid, only to discover you need a gas mask just to stand near the stuff. Furthermore, using acids to clean the pavers may, in fact, eat away the pavers themselves. The end result is a pitted surface, which weakens the pavers by allowing water seepage. In the winter time, the water freezes and expands, eventually cracking the pavers.
So for a hard deep cleaning the answer to the question is “no.” Specialized equipment and cleaning agents are required. More than that, trained skilled technicians who know how to use the equipment are an absolute requirement. You just can’t hire the kid that lives down the block and expect a professional cleaning job. You need trained expertise.
Cleaning, however, is just half the battle. After cleaning, your pavers are super-porous and exposed to the world. They will grime up again in a week if not sealed correctly. A sealer closes up the pores, and does not allow grime to penetrate. Sealers are either solvent based or water based. Again, trained expertise is required to apply a sealer correctly. If applied incorrectly, or if the wrong type of sealer is used, it is all for naught.
Yes, there’s a lot to think about. What first seemed simple turns out to be quite in-depth. Specialized equipment is required, along with the expertise to use it. Confer with professionals in the industry to obtain their input. A good reputable paving company will analyze your pavers, and discuss with you at length what needs to be done.