Utjecaj sastava i kvalitete betona na oštećenja armiranobetonskih ploča uslijed eksplozivnog djelovanja

master's thesis

• Author: Anđela Matković
• Mentor: Marija Kušter Marić (mentor)
• Granter: University of Zagreb; (Croatian Defence Academy "Dr. Franjo Tuđman"); Zagreb
• Defense date and country: 2021-07-01, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Interdisciplinary Technical Sciences

Abstract

U okviru diplomskog rada analiziran je utjecaj sastava i kvalitete betona na nastanak unutarnjih i
vanjskih oštećenja te promjenu svojstava armiranobetonskih ploča uslijed eksplozivnog
djelovanja. Šest uzoraka armiranobetonskih ploča razlikovalo se prema razredu tlačne čvrstoće
(C30/37 - C50/60) te materijalu vlakana za mikroarmiranje (čelična i sintetska). Vizualni pregled
te nerazorne metode ispitivanja (resipod, ultrazvuk i sklerometar) provedene su prije i nakon
eksplozivnog djelovanja. Vizualnim je pregledom izmjerena oštećena i odlomljena površina, dok
se pomoću nerazornih metoda ispitivanja izmjerila električna otpornost betona, brzina prolaska
ultrazvučnog vala te vrijednost odskoka sklerometra koji su prepoznati kao bitni parametri da
utvrđivanje nastalih unutarnjih oštećenja. Na temelju izmjerenih vrijednosti odskoka sklerometra
i laboratorijski određene tlačne čvrstoće za svaki su uzorak određene eksponencijalna i
polinomna korelacijska krivulja te je tlačna čvrstoća svakog od uzoraka procijenjena pomoću
navedenih korelacijskih krivulja i 10% krivulje. Na temelju analiziranih rezultata ispitivanja dan
je zaključak o postignutom učinku eksplozivnog djelovanja na konvencionalno armirane
betonske ploče te ploče s dodatkom navedenih vrsta vlakana. Kako vojni standard za proračun
eksplozivnog naboja ne prepoznaje mikrorarmirani beton, na jedan od uzoraka s dodatkom
čeličnih vlakana postavljena je približno trostruko veća količina eksploziva s ciljem provjere
prikladnosti vojnog proračuna eksplozivnog naboja za rušenje armiranobetonskih elemenata.

Abstract (english)

In this master thesis, the influence of concrete composition and quality on the occurrence of
internal and external damage and the change of properties of reinforced concrete slabs due to
explosive action is analyzed. Six samples of reinforced concrete slabs differ according to the
compressive strength class (C30/37 - C50/60) and the material of fibers for micro-reinforcement
(steel and synthetic). Visual inspection and non-destructive testing method (resipod, ultrasound
and sclerometer) were performed before and after the explosion. During visual inspection the
damaged and spalled concrete surface were measured, while the non-destructive testing methods
were performed in order to measure the electrical resistance of the concrete, the velocity of the
ultrasonic wave and the value of the Schmidt hammer rebound index, which were recognized as
important parameters for determining the internal damage. Based on the measured values of the
Schmidt hammer rebound index and compressive strength determined in the laboratory,
exponential and polynomial correlation curves were determined for each specimen and the
compressive strength of each of the specimens was calculated using the given correlation curves
and the lower 10th percentile curve. The conclusion about the achieved effect of explosive action
on conventionally reinforced concrete slabs and fiber reinforced concrete slabs was based on the
analyzed test results. Since the military standard for the calculation of explosive charge does not
recognize fiber-reinforced concrete, approximately triple amount of explosives was placed on
one of the samples with the addition of steel fibers in order to verify the suitability of the military
calculation of explosive charge for demolition of reinforced concrete elements.

• Keywords: mikroarmirani beton; beton ojačan vlaknima; beton mikroarmiran čeličnim vlaknima; beton mikroarmiran sintetskim vlaknima; eksplozivno djelovanje; kontaktna detonacija; nerazorne metode ispitivanja; korelacijska krivulja
• Keywords (english): micro-reinforced concrete; fiber-reinforced concrete; steel fiber-reinforced concrete; synthetic fiber-reinforced concrete; blast loading; contact detonation; non-destructive testing; correlation curve
• Language: croatian
• URN:NBN: urn:nbn:hr:249:290250
• Study programme: Title: Military Engineering; Study programme type: university; Study level: graduate; Academic / professional title: MAGISTAR/MAGISTRA INŽENJER/INŽENJERKA VOJNOG INŽENJERSTVA (MAGISTAR/MAGISTRA INŽENJER/INŽENJERKA VOJNOG INŽENJERSTVA)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2022-01-10 11:51:41