Struyk, a concrete-paving manufacturer, will be integrated with CRH's existing Dutch paving operations, establishing the company as the market leader in the Netherlands.
Wessem, a brickmaker, will be bolted on to CRH's three existing Dutch brick factories. The Wessem purchase will give CRH a combined capacity of 110 million bricks a year.
Combined trading profits for the two companies were pounds 6.8m in 1991.
Brian Hill, CRH's director with responsibility for continental Europe, said: 'In the course of 1992 we have strengthened our strategic position in the Netherlands by bolt-on acquisitions in three of our core business areas.
'The Braks and Monster acquisitions previously announced reinforce our strong position in the Dutch builders' merchanting industry.
'The addition of Wessem to our clay brick group consolidates our leadership of the quality brick sector, while the acquisition of Struyk significantly strengthens CRH's presence in concrete products on the European mainland.'
CRH shares closed unchanged at 205p yesterday.