# Complex Method of Airfield Pavement Condition Evaluation Based on APCI Index
## 5 Results
### Input Data for APCI Method  
Data delivered to the model developed method come from measurements and field tests and are the results of the degree of degradation, load bearing capacity, anti-skid properties (friction and texture), evenness and tensile bond strength of surface layer. Each of the above-mentioned tests is carried out in a standardized manner, in accordance with the current normative documents. The evaluation of pavement degradation is carried out on the basis of data obtained during the surface inspection. Experts make inventory of damages and repairs of the surface taking into account the type, number and location of individual damage. The overview is subject to each of the concrete or virtual slab. Its location relative to the element is described with two numbers in the row/band layout. In addition, each slab has its own unique identifier which includes the airfield object symbol in the International Civil Aviation Organization notification, the abbreviated name of the airfield functional element and the location of the slab. In the case of large elements (e.g., runway), the entire hectometer of the surface may be evaluated, which corresponds to a fragment of 100 m length. Damages on the slab occur as spot, linear or surface damage. The legend of damage corresponds to the legend of repairs in which the letter markings are identical to damage. In order to distinguish damages from repairs, repairs are recorded black, while damages are red. The quantities of individual damage and repair are referred to the size of the surface on which they were compiled in an inventory and expressed in units: \(\mathrm{pcs/m^{2}}\), \(\mathrm{m/m^{2}}\) or \(\mathrm{m^{2}/m^{2}}\). For the degradation model, each type of damage or repair enters the characteristic weight determined by experts based on many years of experience. The degradation degree of the airfield functional element is a number of dimensions from 0 to 100, where undamaged surfaces are characterized by a degradation indicator equal to 0, while a completely degraded surface has a degradation indicator equal to 100. The assessment of the load capacity of the airfield pavement is done by using the ACN-PCN method. The test based on the Polish military standard NO-17-A500: 2016 Airport and road pavements-load capacity testing [35] and method description can be found in [36]. The values of the elastic deflections obtained in the Heavy Weigh Deflectometer device, the structural layer and material parameters of individual layers, including their stiffness (elasticity module) and bending strength, are considered. In addition, the assessment parameter is taken into account directly under the construction of the assessed element. For information on structures and material parameters of individual layers, full diagnosis is performed by core and ground drilling and a soil substrate probing. Bending strength is converted from the obtained results of splitting tensile strength testing (Brazilian method) of cylindrical samples taken from the structural layers of the pavement. Relationship between splitting tensile strength and compressive strength was described in [37]. The result of the surface load capacity assessment is a commonly used PCN and/or number of allowable air operations for an aircraft with an ACN. In the APCI indicator model, the load capacity is taken into account by the load capacity indicator (\(N\)), which is determined depending on Equation (10). \[N=\left(1-\frac{L}{L_{p}}\right)\cdot 100, \tag{10}\]  
where: \(L\) is number of allowable air operations obtained in load capacity test [-], and \(L_{p}\) is a designed number of air operations [-].