<?php
		$images = get_field('portfolio_gallery');

				if( $images ): ?>
					<ul class="portfolio-slider">
				        <?php foreach( $images as $image ): ?>
				            <li>
				                     <img src="<?php echo $image['sizes']['large']; ?>" alt="<?php echo $image['alt']; ?>" />
				            </li>
				        <?php endforeach; ?>
				    </ul>
				<?php endif; ?>