House Doctor

ANYTHING CAN be interesting if you get into it deeply enough. All right, so a 600-page book called Sewage Plant Design and Practice doesn't exactly leap off the shelf at you but, in the immortal words of Alan Shearer, have you ever thought it could be you?

After all, if you knew your sludges from your effluents, then you might find the latest musings of the world's top sewer bods a riveting read.

The reason I mention this is that I was at a conference on building materials - and yes, there was actually a paper on paint drying - but the high point for me was the conversation I had with the bloke next to me at lunch. When we sat down for our rubber chicken and he told me he was in polymer concrete I naturally feared the worst, but, when I asked him what exactly polymer concrete was, he launched into a tale of sex, violence, wildlife and building materials that left me want- ing more.

It turns out that every year millions of frogs, gripped by the urge to have sex with one another, hop across busy main roads, where, unsurprisingly, they come to a sticky end. Quite why they have to cross the road, rather than just do it in the lay-by like the rest of us, I wasn't too clear about, but, anyway, the nice people who care about frogs decided to install tunnels so the frogs wouldn't get run over. A kind of frog subway. Seems like a sound enough idea; you could have homeless frogs entertaining the others by busking, and that sort of thing.

Trouble was, the first frog tunnels they put in were ordinary concrete drain pipes, and the frogs didn't like going through them; they just carried on hopping across the road and getting run over. So the pipes were investigated by some frog experts who found that the ordinary concrete was sucking the slime off the frogs' feet and they were sticking to the pipes. And the frogs didn't like going into the pipes because it was dark inside and they got claustrophobic; and they actually liked it best if they could see the moon - for navigation purposes or something.

After some experimentation, it was found that the best pipes for frog tunnels were polymer concrete drainage channels with metal grilles on top - just like you drive over every time you enter a petrol station. The polymer concrete uses resins instead of cement to bind the stone aggregate together, which makes it smooth and shiny - so the frogs' feet don't stick to it - and the metal grilles allow them to keep an eye on the night sky. (The reason why you drive over a drainage channel every time you fill the car up is to stop petrol station disasters from flooding the highway - but that's another story.)

So there you go - if I'd said polymer concrete to you five minutes ago, you would have turned the page or gone back to sleep. But now, whenever you hear the term, you will automatically think about our amphibious friends and marvel at the wacky world of building materials. You see, anything can be interesting if you know enough about it.

Struck Off - The First Year of Doctor on the House, by Jeff Howell, is available from Nosecone Publications, PO Box 24650, London E9 7XQ. Price pounds 9, inc postage.

Jeff@doctoronthehouse. demon.co.uk