Accredited laboratory

Construction testing laboratory

The laboratory of NJN Ltd is accredited by the Executive Agency Bulgarian Accreditation Service (BAS) and carries out testing of concrete and aggregates to European and national standards. Our test reports are recognised by the MRDPW, DNSC and the construction supervision authorities in Bulgaria.

EN ISO/IEC 17025 Certificate No 7 ЛИ ИА БСА
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Services

Main areas of testing

Our laboratory works in two main areas — concrete testing and aggregates testing — covering the full range of parameters required by the European standards.

Concrete
Concrete testing
The laboratory carries out a full range of concrete tests to the EN 12350 series (testing of fresh concrete mixes) and EN 12390 series (testing of hardened concrete). The scope includes determination of consistency, water-cement ratio, air content and temperature of fresh concrete, and for hardened concrete — compressive strength, flexural and splitting tensile strength, water impermeability (water absorption under pressure), freeze-thaw resistance and depth of water penetration. Samples are taken on construction sites or at the manufacturing plant. The laboratory is equipped with calibrated presses, moulds and a climatic curing chamber for maturing samples under standard conditions.
EN 12350 — fresh concrete EN 12390 — hardened concrete EN 206 — specification On-site sampling
Aggregates
Testing of rock and aggregate materials
The laboratory tests aggregates for concrete to EN 12620 and for bituminous mixtures and road pavements to EN 13043. The test methods cover the EN 932 series (general properties of aggregates) and EN 933 (geometrical characteristics). The tests include particle size analysis (sieving), particle shape (elongation and shape index), fines content, content of chlorides, sulfates and organic impurities, carbonate content, fragmentation resistance (Los Angeles) and freeze resistance. The laboratory works with quarries, crushing plants and concrete mix producers in Southern Bulgaria.
EN 932 — general properties EN 933 — geometrical characteristics EN 12620 — aggregates for concrete EN 13043 — aggregates for roads
Tests

Scope of accreditation

The full scope of accredited tests under BAS Certificate reg. No 7 ЛИ (valid until 26.04.2028), Order No А 156/26.04.2024.

Concrete mix
Concrete mix (fresh concrete)
Testing of fresh concrete mixes immediately after preparation — on site or at the plant:
  • Slump (БДС EN 12350-2)
  • Density (БДС EN 12350-6)
  • Air content (БДС EN 12350-7, item 6)
  • Flow (БДС EN 12350-8)
Hardened concrete
Hardened concrete
Testing of hardened concrete under standard curing conditions:
  • Compressive strength (БДС EN 12390-3)
  • Flexural tensile strength (БДС EN 12390-5)
  • Density (БДС EN 12390-7)
  • Depth of water penetration under pressure (БДС EN 12390-8)
  • Water impermeability (БДС EN 206/NA, Annex NA.N)
  • Freeze-thaw resistance — direct method: mass loss and compressive strength (БДС EN 206/NA, Annex NA.O.1)
  • Freeze-thaw resistance — accelerated method: mass loss and reduction of ultrasonic pulse velocity (БДС EN 206/NA, Annex NA.O.2; БДС EN 12504-4)
Geometrical characteristics
Geometrical characteristics of aggregates and rock materials
Tests for aggregates for concrete and mortars, rock materials for roads, crushed stone and fine fillers:
  • Particle size distribution (БДС EN 933-1)
  • Fines content (БДС EN 933-1)
  • Flakiness index (БДС EN 933-3)
  • Shape index (БДС EN 933-4)
  • Percentage of crushed, totally crushed and totally rounded particles (БДС EN 933-5)
  • Shell content (БДС EN 933-7)
  • Sand equivalent (БДС EN 933-8+/A1)
  • Particle size distribution of fine fillers (БДС EN 933-10)
  • Constituents of coarse recycled rock materials (БДС EN 933-11)
Physico-mechanical properties
Physico-mechanical properties of aggregates and rock materials
Tests for strength, density and durability characteristics of aggregates and rock materials:
  • Resistance to wear — micro-Deval (БДС EN 1097-1)
  • Resistance to fragmentation — Los Angeles (БДС EN 1097-2, item 5)
  • Crushing under static load (БДС EN 206/NA, Annex NA.Q)
  • Fineness modulus of sand (БДС EN 12620+A1, Annex B)
  • Loose bulk density and percentage of voids (БДС EN 1097-3)
  • Water content (БДС EN 1097-5)
  • Particle density and water absorption (БДС EN 1097-6)
  • Freeze-thaw resistance (БДС EN 1367-1; БДС EN 13450, Annex F)
  • Resistance to weathering — magnesium sulfate value (БДС EN 1367-2; БДС EN 13450, Annex G)
Process

How the laboratory works

The process from enquiry to receipt of the test report is optimised for speed and reliability, in full compliance with the requirements of EN ISO/IEC 17025.

01
Enquiry
The client sends an enquiry by phone or email with a description of the desired tests and the type of samples
02
Sample acceptance
Samples are accepted at the laboratory or taken on site by our specialists following an established procedure
03
Testing
Tests are carried out by qualified personnel using accredited methods with calibrated equipment
04
Report
Issuance of an official test report with the results, the measurement uncertainty and a reference to the methods
Accreditation

Accreditation under EN ISO/IEC 17025

The laboratory is accredited by the Executive Agency Bulgarian Accreditation Service (BAS) — the national accreditation body of Bulgaria, a full member of EA and ILAC.

№ 7 ЛИ
Accreditation certificate
The laboratory holds Accreditation Certificate No 7 ЛИ, issued by BAS. The certificate attests accreditation under EN ISO/IEC 17025 — the international standard for the competence of testing and calibration laboratories. The current scope of accreditation is publicly available on the BAS website.
2021
Year of accreditation
The laboratory has been accredited since 2021 and successfully passes the surveillance and re-accreditation assessments of BAS. The accreditation is confirmed through periodic assessments by BAS teams, including technical assessors — specialists in the field of concrete and aggregates.
ILAC
International recognition
BAS has signed the mutual recognition arrangements of ILAC (International Laboratory Accreditation Cooperation) and EA (European Accreditation). The test reports issued by our laboratory are automatically recognised in more than 100 countries worldwide, without the need for additional checks or repeat testing.

Do you need laboratory testing?

Contact our laboratory for a quote and information on turnaround times. We work with concrete producers, construction firms, designers and investors in Southern Bulgaria and across the country.

Send an enquiry +359 38 585 804
Documents

Documents for download

PDF
Application
Test application form