Using Portland Cement for rocks?

I wonder if anyone in this forum has any experience using cement either for backgrounds or artificial rocks in their planted aquariums?

I have found a few articles on how to use Portland Cement for artificial rocks. But I have a concern that it might increase the water's pH and hardness and limit the plants I can grow.

Is there a way to cure Portland Cement so that it becomes mostly inert?

Or is there another material I can use that is more suitable for freshwater planted aquariums?

Thanks for any info!