I mixed 1:1.5:3 by hand and using a bucket. I mixed the concrete on a plastic sheet but on hard soil not a concrete surface. I am not sure what I have done wrong. The portland cement bag suggested 1:4:3.5. It seems like that people here use more sand than coarse aggregates. I created this pad for a small sliding gate motor. Is it going to have problems? What went wrong? Too little sand?
If you want no holes, you have to compact it, easiest is with vibration but that needs a special tool. Or you can poke a stick in and out of it for a while. I've had great success by fastening a bit of wood plank on the business end of a vibrating sander and using that as a vibrating float.
Don't worry though, you're not building a suspension bridge, it's not going to come apart. If it was a thin load-bearing shape like a slab, then it would be worrying to have it "pre-fractured" like that, but this is a big chunky block whose only job is to be heavy and take a few screw anchors.
If the holes are an aesthetic problem, you can always cover it with a mortar made with a mix of fine sand and cement, apply like plaster.
For next time:
Since this is not a load bearing item like a slab, you can put in a bit too much water so it flows better. It will be a bit weaker, and have a bit more cracks, none of it matter for what is basically a concrete boat anchor. Or you could mix in some concrete plasticizer, which makes it a lot easier to work with without compromise in solidity, but that's a bit expensive and way overkill for this job.