Laravel collection union during each not working - laravel

Question

I have a probleme with union() that not insert my new collection
During my each I have the $mean collection with witch I search the slices() I test and have some $_availabaleSlices to insert into my $slices (id: 4 then id:7)
But after the whole code passed I only have the first $_availabaleSlices inside the $slices.
What I have made wrong ?
The code
$slices = new Collection();
Means::whereIn('id', $meansId)
->get()
->each(function ($mean) use (&$slices, $weight) {
$_availabaleSlices = $mean->slices()
->betweenWeight($weight)
->get();
if (0 < $_availabaleSlices->count()) {
dump('NEEDED',$_availabaleSlices->toArray());
dump('BEFORE',$slices->toArray());
$slices = $slices->union($_availabaleSlices);
dump('AFTER',$slices->toArray());
}
});
dd('RESULTS', $slices->toArray());
The Results
"NEEDED"
array:1 [
0 => array:5 [
"id" => 4
"deliveries_mean_id" => 3
"weight_min" => 250.0
"weight_max" => 600.0
"deleted_at" => null
]
]
"BEFORE"
[]
"AFTER"
array:1 [
0 => array:5 [
"id" => 4
"deliveries_mean_id" => 3
"weight_min" => 250.0
"weight_max" => 600.0
"deleted_at" => null
]
]
"NEEDED"
array:1 [
0 => array:5 [
"id" => 7
"deliveries_mean_id" => 4
"weight_min" => 150.0
"weight_max" => 700.0
"deleted_at" => null
]
]
"BEFORE"
array:1 [
0 => array:5 [
"id" => 4
"deliveries_mean_id" => 3
"weight_min" => 250.0
"weight_max" => 600.0
"deleted_at" => null
]
]
"AFTER"
array:1 [
0 => array:5 [
"id" => 4
"deliveries_mean_id" => 3
"weight_min" => 250.0
"weight_max" => 600.0
"deleted_at" => null
]
]
"RESULTS"
array:1 [
0 => array:5 [
"id" => 4
"deliveries_mean_id" => 3
"weight_min" => 250.0
"weight_max" => 600.0
"deleted_at" => null
]
]

Answer 1

Found the solution. I needed to use ->merge() and not ->union().