In 1994, Dave Grohl founded the Foo Fighters from the rubble of a tragedy. Following former Nirvana bandmate Kurt Cobain’s highly publicized death, Grohl found himself in a silent Seattle — Nirvana was over, and there were no more shows to play. 23 years later, the Foo Fighters have released their ninth-studio album titled “Concrete and Gold.” The name suits the band’s sonic mix of hard, grungy rock — which carries the tone of Grohl’s former fame. The album as a whole highlights his lyrical poeticism and demonstrates his tremendous growth and maturity as a songwriter. If hard rock past, fraught with hardship, is the concrete the Foo Fighters are built upon, then they have managed to spin concrete into gold. “Concrete and Gold” is another solid step for the Foo Fighters, continuing their track record of delivering chart-topping alternative rock albums since their formation over a decade ago. Previously released singles such as “Run” and “The Sky is a Neighborhood” are certainly no-fail rock tracks, but it’s the more experimental pieces that shine on this record — demonstrating progress for the band. For example, the album starts quietly — acoustically, to be exact — and Foo Fighters songs are typically anything but hushed. The initial calm of the opening track “T-Shirt” does not last long, though — after 28 seconds, the sound explodes, and the band’s characteristic crunchy guitar riffs and pounding drum beats are back in full force. Three tracks in, the Foo Fighters introduce a highly unexpected collaboration into the mix. On “Make It Right,” the smooth guest vocals heard behind the beating cymbals and jazzy guitar lines is none other than popstar Justin Timberlake. In terms of music matches, the Grohl-Timberlake pair was certainly not on anyone’s radar as a potential combination. Still, it somehow works. A bouncing melody line — which takes cues from old-school rock bands Led Zeppelin and Pink Floyd — gives Timberlake’s falsetto harmonies a platform to shine. Later on in the album, the guest star role is filled by another boy band sensation — on “Sunday Rain,” Paul McCartney steps in as the drummer. McCartney donates more than simply beats to the track, but rather leaves his musical mark on the piece as a whole. “Sunday Rain” sounds like a Foo Fighters chart-topper, dipped — or soaked — in the Beatles’ “White Album.” Again, the Foo Fighters find a way to make it function. In fact, “Sunday Rain” and “Make It Right” could easily be the best songs on the album. Perhaps these collaborations were the solution to the ever-present question that haunts the rock genre as a whole. How does a rock band keep up with the times of electro-pop and hip-hop without losing the integrity of their band? The Foo Fighters are already a rarity — a surviving rock band quite literally formed from the ashes of another, more-famous group that was cloaked in the chaos of artistic angst and pop culture speculation. It’s a commonly known fact that rock bands often break up, citing dramatic differences and lives gone a little too wild. It’s another commonly known fact that some rock bands “sell out,” trading in their Telecasters for technology and their bass guitars for “beats.” The Foo Fighters have skillfully avoided this fall from grace, and they have an album full of guest artists to thank for it. Instead of going pop, they made pop — in the form of Justin Timberlake collab jams — rock. The album closes with the title track, “Concrete and Gold.” Layered on a scratchy, echoing guitar riff, Grohl sings, “Our roots are stronger than you know / Up through the concrete we will grow.” In just one line, he summarizes his own band’s strength. With their feet firmly set in the history of rock music but their eyes towards the future, the Foo Fighters have maintained their roles as prominent rock-and-roll icons. The band is back in full action after a three-year album drought, and there are no signs of them stopping.