<?php
        $paged = ( get_query_var( 'paged' ) ) ? get_query_var('paged') : 1;
        $cat_id = 42;
        $child_categories=get_categories(
            array( 'parent' => $cat_id )
        );

        foreach ( $child_categories as $child ) { ?>
          <!-- loop through child categories and make columns -->
            <div class="col-sm-4">

            <!-- category title -->
            <?php
              $string = $child ->cat_name;
              $className = str_replace(' ', '', $string);
             ?>
             <h2 class="cat-icon <?php echo $className; ?>"><?php echo $child ->cat_name; ?></h2>

             <!-- query -->
             <?php  $args = array(  'category_name' => $child->cat_name, 'posts_per_page' => -1, 'paged' => $paged, 'orderby' => 'title', 'order' => 'ASC'  );
              $loop = new WP_Query( $args ); ?>

            <!-- loop to create buttons -->
            <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
              <?php get_template_part("home", "service-button"); ?>
            <?php endwhile; ?>


          </div>

        <?php } ?><!-- end foreach loop -->