Laravel sum query using join and distinct

   $idsDue = Amortization::distinct()
                           ->select('loan_id')
                           ->where('payment_status',0)
                           ->where('schedule', '<', date('Y-m-d'))
                           ->where('past_due', '<=', 30)
                           ->get();

    $oneToThirtyDue = Loan::select('loan_type',\DB::raw('SUM(loan_balance) as total_val'))
                                  ->whereIn('id',$idsDue)
                                  ->groupBy('loan_type')
                                  ->orderBy('loan_type')
                                  ->get();