Laboratory Testing of Construction Materials

SAŽETAK:
                                           
Tvrdoća je  važno  svojstvo  metalnih  materijala, koje daje  dosta informacija o materijalu, na osnovu kojih se mogu odrediti ostala  mehanička svojstva. U ovom radu su predstavljeni rezultati ispitivanja tvrdoće precipitaciono ojačanog nehrđajućeg čelika 17-7PH sa modifikovanim hemijskim sastavom u stanju nakon termičkih tretmana TH1050 i RH950. Regresiona analiza je pokazala koje su varijable statistički značajne za predviđanje vrijednosti tvrdoće  HV10 u čeliku 17-7PH sa modifikovanim hemijskim sastavom.

Ključne riječi: čelik 17-7PH, tvrdoća, regresija, precipitaciono ojačavanje

ABSTRACT:

Hardness is an important property of metallic materials, which gives a lot of information about the material on the basis of which to define other mechanical properties. In this paper is presented the results of tests of hardness of precipitation hardened stainless steel    17-7PH with modified chemical composition, heat treated in conditions TH1050 and RH950. Regression analysis showed which variables are statistically significant in predicting the value of the hardness HV10 of the steel 17-7PH chemically modified composition.

Keywords: steel 17-7PH, hardness, regession, precipitation hardening

Natural slates for roofing and cladding in the commercial definition have different but often marine genesis.
They are easily cleavable and suitable to use for discontinuous roofing and external wall cladding. These finegrained
shales have mostly a (transverse to the bedding) slaty cleavage or in the case of the parallel slate a lithostatic
cleavage parallel to the stratification.
In the worldwide view the high quality slate deposits are Proterozoic and Paleozoic and originate e.g. from
Caledonian and Hercynian orogenies (Fig. 1). In addition there are also unfolded deposits of parallel slate in old
cratons.
The national requirements and methods were very diverse. The discussion in favour of a common European
standard (EN 12326) during more than 10 years accompanied by a scientific research generated results which are
explained and criticised.
The analyses of petrographic fabrics give information on the fissility of slate and the efficiency of the slate
manufacturing but do not clarify the geological genesis. This paper publishes a scheme for estimation of the fabric
of slate (Fig. 2), the microscopic measurement of number (Fig. 3) and thickness of mica layers, and the mass value
(= number of mica layers per mm x thickness of layers in mm x 10; Fig. 4) and their pros and cons.
The exact definition of the fine-grained mineralogical composition is difficult; therefore a calculation of the
slate’s norm minerals (slatenorm) like in the CIPW-norm for magmatic rocks could be helpful.
The ternary diagram for applied properties (e.g. thickness and fissility) from Le Corre (1970; see Fig. 5) is not
applicable to several oversea slates. This paper originates a new alternative diagram (Fig. 6) which, apart from the
quartz content, uses the parallel texture as well, specified in the number of mica layers per mm.
The requirements of the thermal cycle resistance (i.e. oxidation resistance of the metallic minerals) given in the
EN 12326 are with the classifying of T1, T2, and T3 too low and imprecise, therefore this paper proposes a subdivision
of T1 in a, b, and c. The microscopic petrographic analysis on polished thin sections can describe the oxidation
resistance of the metallic minerals as follow (Fig. 7):
T1a, containing very little pyrite framboids and small monocrystals or stable minerals of the mixed crystals of
ilmenite/titanomagnetite/magnetite, is stainless.
T1b (Plate 1: Fig. D) and T1c containing pyrrhotite and bigger accumulations of micropyrites shall be deemed
to be not stable, whereas the cristallinity of these metallic minerals with regard to the reaction rate are important.
T2 (Plate 1: Figs. E and F) and T3 are exceptions of the types T1b and T1c with the same characteristics but in
combination with other unstable minerals like carbonates or unfavourable technical properties like e.g. higher water
absorptions (> 0.4 M.-%). Big metallic minerals, which penetrate the slate pose a risk of forming holes representing
code T3 (Plate 1: Fig. G), because of the different thermal expansion.
EN 12326 gives simple requirements according to other not weather resisting minerals like carbonates and
non-carbonate carbon. In addition the petrographical properties and the integration of these minerals (Plate 2:
Figs. C to G) in the slate fabric are important for the durability.
The petrographical methods can be used only in sum for the control of the origin of the slate (Plate 1: Fig. C).
A decision with only one method like e.g. the mass value is not suitable.
The Europe-wide harmonised test methods of the EN 12326 enable scientific correlations between the modulus
of rupture and the water absorption (Fig. 8) or alternatively the parallel texture (i.e. mica layers/mm; Fig. 9).
The grain (definition given in the EN) results in an anisotropic bending strength like in Fig. 10.
The CE-marking (German form: Fig. 11) should inform the user about all main slate properties, but in fact the
user need further information about the risk of oxidation given in a distinction between T1a (no risk) and T1b, c
and in several petrographical tests proposed in this paper.

Spectro Analytical Labs is pioneer in providing Material Testing, Inspection, Non Destructive analysis of various structures. Spectro provides reliable acerate & reproducible test results. The Analysis is conducted in compliance to various is standard including, IS, ASTM, BIS, ISO etc. Spectro owe its credibility to accreditation received from NABL & also a world - class  sophisticates Laboratory.

Service quality in a construction technology laboratory can result in an improvement in construction companies’ competitiveness. This research aims to evaluate the service quality provided by a construction technology laboratory, specifically in the segment of performing testing through the rupturing of concrete samples. For this research, a survey was conducted using a structured questionnaire that was created based on a literature review regarding the surveying of laboratory customers at a university in the south of Brazil. Our research was both exploratory and quantitative, and the data were analyzed by applying multivariate data analysis. The conclusions of this study show that the dimensions of quality services are: communication, reliability, responsiveness, credibility, and tangibility. These five dimensions together provide a high explained variance standard of 79.75%. Having a suitable number of attendants available to serve customers and presenting agility in the construction laboratory is one of the managerial research contributions. Moreover, through information availability, this research generates greater traceability that can be used both by customers and by institutional management. Constantly and thoroughly monitoring the customer service cycle is another relevant factor that can improve the quality of the services provided.