M&A speculation surrounding CRH and a broker upgrade for Balfour Beatty were giving the UK construction and materials sector a lift on Friday.Building materials firm CRH was 2.5% higher, extending gains made on Thursday after confirming speculation that it was in talks to buy some of Lafarge and Holmium's assets ahead of their proposed merger.Mike van Dulken from Accendo Markets said the potential purchase "could bolster CRH's market presence in the region easily thanks to overlapping business allowing simple integration of new businesses with existing operations".Balfour Beatty was up nearly 5% as the stock continued to rise following a well-received update the previous session after a less-than-expected profit warning from its UK construction division.Numis Securities upgraded its rating on the stock from 'hold' to 'add', saying that the KPMG review into the business "should draw a line under issues" and the company is "turning the corner".James Halstead, Henry Boot, Galliford Try, Michelmersh Brick, Polypipe and Tyman were also in demand in London.Building services firm T Clarke was also extending gains after a well-received update on Thursday, in which it said that market conditions were improving, particularly in London.On a negative note, glass fibre insulation group Superglass was bucking the trend with shares down 6% after the announcement that non-executive director David Gray was stepping down in April after six years. Top performing sectors so far todayFood Producers & Processors 8,168.75 +2.52%Construction & Materials 4,477.10 +2.50%Personal Goods 26,663.32 +2.09%Fixed Line Telecommunications 4,873.80 +2.05%Household Goods & Home Construction 12,998.14 +1.57%Bottom performing sectors so far todayMining 13,550.28 -3.44%Oil Equipment, Services & Distribution 15,365.52 -3.11%Industrial Metals & Mining 1,705.80 -1.08%Automobiles & Parts 8,765.41 -0.98%Chemicals 11,837.66 -0.82%