The Yellow Book is not dead, but it is certainly limping.
The trackability of on-line ads makes it a FAR better option.
BUUUUT, just like anything, you should get the help of someone with experience.
Some basic tips:
1. For your type of business, you should only be doing geographic-targeted online ads on google. Not blanket ads which are more expensive and seen by the world.
2. Set up a campaign that lead to different landing pages on your website. This will give you the best tracking evidence. After watching your stats for 1-2 months, completely shut down the lowest performers and plug their money into the higher performers. For the middle performers, make minor tweaks to see if you can improve numbers.
3. Organic performance on Google is higher cost up-front but your results are forever. We have all but stopped our PPC (pay per click) ads now that our organic has gained momentum. WARNING: Be careful of shady tactics. These will get you banned from major search engines.
4. Link juice offers to new customers-- every time you sign on a new customer, offer some kind of freebie that doesn't cost you much for a link from their site to yours. Inbound links greatly increase your organic performance. You could even use small discounts and mark the dollars lost as marketing costs.
5. THIS ONE IS SHAKY KNOWING YOUR TYPING HISTORY: Try writing some self-help or how-to articles about concrete and posting on your site. If your keyword density is the right percentage it will also help your organic ranking.
6. Make your search terms very targeted. Not "Concrete". If you specialize or have higher margins on a certain type of concrete work, make that 80% of your on-line focus.
NOTE: "Organic" ranking is the links that you see in the middle of Google searches. Not the paid ones at the top and on the side.
As stated, all of these tips are SEO 101.
Paying for clicks is ok, but growing your site organically is no doubt a better investment.