Custom tax_query not working

Hi, guys

I’m trying to create a page template with a custom taxonomy query that only shows posts from a specific category (the category name is “blog”), but I can’t make it work.

This is the code I have so far:

<?php $category_posts = new WP_query( array(
	'orderby' => 'post_date',
	'paged' => $paged,
        'tax_query' => array(
            array(
                'taxonomy' => 'category',
                'field'    => 'slug',
                'terms'    => 'blog'
            )
        )
) ); ?>

<?php if ( $category_posts->have_posts()) : ?>

		<?php while ( $category_posts->have_posts() ) : $category_posts->the_post(); ?>
			<?php get_template_part( 'content', get_post_format() ); ?>
		<?php endwhile; ?>

The above displays posts from all categories and I don’t understand why. Any help you can provide in this regard is much appreciated!

Luis