try this. i am not sure it would work for masonary layout or not. but it would give you an idea on how to make rows and columns within loop.
if ($news->have_posts() ) : while ($news->have_posts() ) : $news->the_post();
//$value = $news->current_post;
if($value % 3 == 0){
?>
<div class="row">
echo "<div class="col-lg-4">";
<div class="height <?php foreach(get_the_category() as $category) { echo $category->slug . ' ';} ?>">
<div class="text">
<h5><?php the_time('F jS, Y'); ?></h5>
<h4><a href=""><?php the_title(); ?></a></h4>
<?php the_excerpt(); ?>
</div>
</div>
<?php
//$i++;
//print($value);
}
echo "</div>";
if($value % 3 !== 0){
echo "<div class="col-lg-4">";
echo "</div">
}
endwhile; endif;