The available RPM packages ignore the packages that are available/installed within RHSCL. If I want to install zabbix-web-mysql, RPM always wants to install the packages php-* and httpd-*.
But through RHSCL i've already installed the packages httpd24-* and php55-*. Maybe the dependencie should be completly removed? Since it's also not trying to install MySQL.
RHSCL is supported by Redhat and publish newer PHP, Apache and Maria releases through this channel.
You can find here a list of the included packages: