Striking of vertical concrete elements: An analysis using the maturity method

• Differences in estimated striking times proposed by existing standards and authors are analyzed.
• A methodology for the striking of vertical concrete elements is presented.
• An experimental program is developed in order to validate the proposed methodology.
• A minimum resistance and maturity index to formwork removal it is proposed.

For the construction of vertical concrete elements, temporary structures called formworks are generally used. These represent one of the major costs for construction companies, and can rise up to 60% of the total cost of the project.The existing standards and authors that refer to the striking of vertical formworks (columns and walls), present many differences in estimated striking times; moreover, there is no universally accepted method to predict these. Generally, the mechanism and time of striking are arbitrarily decided at the construction site and there is no theory to relate environmental and concrete factors with the optimal formwork striking times.In this article, a methodology for striking vertical concrete elements by means of the Maturity Method is presented, which takes into consideration the temperature variations between pouring and striking of concrete. This methodology can predict the minimum striking time independently from the type of concrete, by continuously measuring its maturity index at the construction site. An experimental program was carried out and the results show that for the studied dosage the recommended striking strength is 2 MPa.