Clay sales volumes were around 80% of pre-coronavirus levels in July with concrete sales volumes at around 85%.
Sales in June had been 60% of previous while in April the number dropped to just 10%.
Revenues in the half-year to June dropped 36% to £131m, while the company posted a statutory loss of £52mln.
John Hudson, chief executive, said: "We entered the crisis with a strong balance sheet.
“Decisive management action at the outset of the pandemic to control costs and preserve cash ensured the group was adjusted free cash flow positive during the second quarter and we remain in a solid financial position.
"The fundamentals for our markets remain positive, with a substantial housing deficit in the UK and Government policy which is supportive of the role the construction sector will play in the UK economic recovery.”
Shares dropped 3% to 162.8p.