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Abstract

Among various construction activities, related to concrete pavement technologies, an important role is reserved to industrial floors. For these structures it is necessary to ensure resistance and stability, durability, reliability, and many other properties. In particular, the flatness and the levelness are special requirements that assume a real significance respect to functional performances, especially when the pavement has to allow the movement of vehicles and goods or the storage in elevated stacks or shelves. These geometric properties can be defined in different ways, but in every cases they are referred to pavement surface, that has to be even (without superelevated or depressed areas) and level (horizontal, without grades, curvatures, and waves). The acceptance limits are defined by technical standards, in various countries, together with the suitable methods for measurements and controls. In many cases, however, these methods are considered not really feasible or easy, in particular when a continuous sampling of the pavement, along selected alignments, is needed. In particular, the paper describes the operating procedures to calculate indexes FF and FL, according to ASTM 1155M standard, starting from data provided by a contact profilometer. If the target values are not reach, it is necessary to provide some alternative solutions to avoid the demolition of the slabs or the payment of penalties by the builder, if this is required by the contract. There are two main possible methods for increasing flatness and levelness while other functional surface properties are maintained at the expected levels: the surface grinding and the overtopping with self-levelling and high resistance resins. A case study where the two alternative methods are applied to improve flatness and levelness of a surface is presented. The results of measures made before and after the treatments showed that both the solutions are able to ensure, within certain limits, the fulfillment of the requirements and consequently they can be used for the proposed aims.

6. Conclusions

In the construction of concrete pavements for industrial floors, it is important to ensure some functional properties regarding the surface regularity, that have the same importance as the mechanical and structural characteristics. Goods storage capacity and operational conditions in warehouse and logistic centers, in fact, can be significantly influenced by the conditions of floors’ surfaces. Two parameters are usefulto characterize these important properties:the “levelness”,thatindicates the surface regularity over a distance equal or more than 3 m, and the “flatness”, used to evaluate the regularity over a distance typically equal to 300 mm. The definition of both the two variables is generally based on measurements along some selected alignments (surfaces profiles), that are actually performed by means of special equipment (contact profilometers, usually), and on the calculations ofdifferencesbetweentheheight ofpoints onthe real surface andthose onanideal referenceplan. The evaluation of flatness and levelness, along the selected profiles on a paved surface, can be achieved by means of some indexes established by the technical standards. In particular – following the procedures of the ASTM 1155M – two indexes named FF and FL can be used; these indexes allow to obtain a concise and expressive representation of the functional properties concerning the floors’ regularity. However, considering that measurements can be locally affected by various specific problems and they can be not really representative of the functional performances, it is necessary to perform a statistical process consisting in the calculation of the two basic statistic variables: the mean and the standard deviation of the values in the sample. In this paper, after a revue of the principles regarding the functional performances for industrial floors and some indications to the standard requirements for data acquisition and processing, three surfaces belonging to an industrial concrete floor were presented as a case study. For these test sections, the indexes of flatness and levelness were determined, with the purpose to evaluate the efficacy of two possible improving treatments: the surface grinding and the overtopping with self-levelling and high resistance resins. After the completion of these actions, other measurements and evaluation were performed and the results allowed to compare the different achieved levels of flatness and levelness and to demonstrate the advantages of the experimented treatments.