The sale, to Indian steel tycoon Lakshmi Mittal, was a condition set by Britain's Competition Commission to allow the two firms to combine their building materials activities.
Lafarge and Anglo said on Friday they would sell a number of construction materials operations in Britain as well as Anglo unit Tarmac's 50 percent interest in Midland Quarry Products, one of the UK's main suppliers of hard rock and asphalts.
Nomura analysts said the deal could be seen as a positive for investors fretting over a potential rights issue at the Mittal family's debt-burdened flagship asset, ArcelorMittal , the world's largest steelmaker.
Spending $450 million on construction material assets now does not necessarily sound like someone who is thinking about imminently piling in a few billion dollars into his steel business as part of an equity raise, they said.
Anglo, refocusing on core mining activities, struggled for more than three years to find a buyer for Tarmac before agreeing last year to a joint venture with France-based Lafarge's British cement, aggregates, concrete and asphalt businesses.
The price for the assets, which include one of the UK's largest cement plants, includes up to 30 million pounds contingent on future performance.
A Lafarge spokeswoman said the company would receive around 160 million euros ($205 million) from the sale of its British assets, which it would use to cut its debt.
She added that with this deal, Lafarge had raised nearly 650 million euros from asset sales this year against a target of at least 1 billion euros.
The French company has been shedding non-core assets and refocusing on its cement and concrete business after the debt it racked up to acquire Middle Eastern cement maker Orascom in 2007 led to the loss of its investment-grade credit rating last year.
Britain's Competition Commission began looking into the proposed venture, which would have rung up annual sales worth 1.8 billion pounds ($2.9 billion) in 2010, after the tie-up was challenged by the country's consumer affairs watchdog, the Office of Fair Trading, in September last year.
Lafarge's Hope cement plant in northern England is one of the largest in Britain, and regulators hoped its sale will bring in a new player to maintain the current level of competition. The UK cement market is dominated by Lafarge, Tarmac, Cemex and HeidelbergCement's Hanson.
Lafarge shares were up 0.2 percent at 45.72 euros on the CAC40 index in early trade, while Anglo American was trading 0.3 percent higher at 1,695 pence on London's FTSE100 index. ArcelorMittal shares were 0.1 percent higher.