Characterising Penetrometer Tip Contact during Concrete Condition Assessment

Concrete condition assessing penetrometers need to be able to distinguish between making contact with a hard (concrete) surface as opposed to a semi-solid (corroded concrete) surface. If a hard surface is mistaken for a soft surface, concrete corrosion may be over-estimated, with the potential for triggering unnecessary remediation works. Unfortunately, the variably-angled surface of a concrete pipe can cause the tip of a force-sensing tactile penetrometer to slip and thus to make this mistake. We investigated whether different shaped tips of a cylindrical penetrometer were better than others at maintaining contact with concrete and not slipping. We designed a range of simple symmetric tip shapes, controlled by a single superellipse parameter. We performed a finite element analysis of these parametric models in SolidWorks before machining in stainless steel. We tested our penetrometer tips on a concrete paver cut to four angles at 20∘ increments. The results indicate that penetrometers with a squircle-shaped steel tip (a=b=1,n=4) have the least slip, in the context of concrete condition assessment.

AN AUTOETHNOGRAPHIC ACCOUNT OF TWO INDONESIAN ACADEMIC RETURNEES EXPERIENCED OF REVERSE CULTURE SHOCK

In this article, we use an autoethnography approach to reflect on our emotional experiences of re-integrating in academic community in two different universities. We start to explore our experience of implementing new knowledge in teaching and researching, demonstrating how we as junior lecturers often making confrontations with the ‘conventional’ and ‘traditional’ sounded educational system which have been practiced by senior colleagues. In this sense, there has been a conflictual emotion which we should address, utilizing our new knowledge or returning back to the existing norms. Whilst exploring our experiences of dealing with conflictual emotional beliefs, we also examine issue such as identity construction as being an academic returnee responding to the confrontation in academic environment. This study results may resonate the concrete condition of academic returnees re-integrating to their academic milieu in other part of the countries.

Cartridge Music in the Quarantine: Presence, Absence, Contingency Setups and (De-)territorialised Performances

Between the end of May and the beginning of June, 2020, we performed individually, filmed, synced together, edited and presented a quarantine version of John Cage’s Cartridge Music. Uploaded on YouTube, the performance was broadcast on 1 June, as part of the 4th Research Colloquium of the Postgraduate Programme in Music of the Federal University of Paraíba. Stranded at home since March, unable to reach our respective faculty offices/studios, and mostly left with domestic gear, kitchenware, sound-producing car equipment and our children’s toys, we put together an emergency version of the piece, characterised by three dramatically different setups, each with its own spatialities and soundworlds. Importantly, our use of the signifier “emergency” here is meant to refer much more to the concrete condition of our existences in this particular situation, than to the contingential circumstances of this specific musical activity. In this paper, we discuss the piece by considering its preparation, performance, presentation the (de-)territorialisation of performance and on the territorial metaphors embedded in collaborative artistic interaction, we question the notions of “place” and “venue” in the context of a collective performance that happened in three different locations and of a subsequent première that did not happen in any tangible physical place at all. However, and in spite of the substantial de-territorialisation of our gig, we also consider a set of persisting spatial narratives that inscribe the performance in terms of both visually and aurally perceptible power relations. Finally, considering the inherent criticalities of the field(s) of “experimental”, “avant-garde” or simply “contemporary” music, we assess the gains and losses of such a dematerialised and yet ubiquitous performance in terms of audience participation and appreciation.

IDENTIFIKASI DEGRADASI MUTU BETON PADA STRUKTUR BANGUNAN GEDUNG DI JAKARTA

Concrete quality degradation is a concrete quality downgrade from the perspective of concrete tension. Concrete quality degradation on concrete structure can happen either on new buildings (buildings that are still being constructed/in construction phase) or existing buildings (buildings that are already operational/in operational phase). The possible causes of concrete quality degradation on new buildings are, among others: incorrect implementation process such as readymix concrete quality that isn’t according to plan, lack of compacting, inadequate maintenance. Concrete quality degradation examination is done by examining concrete tension. On new buildings, one of the ways concrete tension can be identified is through test object examination. Concrete is a construction material that has a unique tension trait, where if it’s examined with a number of test objects, the value will spread around one particular average value. The value number depends on the field implementation perfection level. If the concrete tension of test object isn’t according to plan, installed concrete assessment with destructive and non destructive method can be performed. This research is done to identify the amount of concrete quality degradation on building structure based on tension value of concrete test object at the construction phase. Analysis results show the occurrence of a large concrete quality degradation, necessitating the determination of characteristics and categories until the worst possible concrete condition for concrete condition assessment needs. AbstrakDegradasi mutu beton adalah penurunan kualitas beton dilihat dari kuat tekan beton. Degradasi mutu beton pada struktur beton dapat terjadi baik pada bangunan baru (bangunan yang sedang dibangun/tahap konstruksi) maupun bangunan existing (bangunan yang sudah beroperasi/tahap operasional). Penyebab degradasi mutu beton pada bangunan baru diantaranya ada bagian pada proses pelaksanaan yang kurang tepat seperti mutu beton readymix tidak sesuai rencana, kurangnya pemadatan, perawatan beton kurang baik. Pemeriksaan degradasi mutu beton dilakukan dengan memeriksa kuat tekan beton. Pada bangunan baru, kuat tekan beton dapat diketahui salah satunya melalui pengujian benda uji. Beton adalah suatu bahan konstruksi yang mempunyai sifat kekuatan tekan yang khas, yaitu apabila diperiksa dengan sejumlah besar benda uji, nilainya akan menyebar sekitar suatu nilai rata-rata tertentu. Besar atau kecil nilai bergantung pada tingkat kesempurnaan pelaksanaan di lapangan. Apabila kuat tekan beton dari benda uji tidak sesuai rencana maka dapat dilakukan pengujian beton terpasang dengan metode non destruktif dan destruktif. Penelitian ini dilakukan untuk mengetahui besarnya degradasi mutu beton pada struktur bangunan gedung bertingkat berdasarkan nilai kekuatan tekan benda uji beton pada tahap konstruksi. Hasil analisis menunjukkan terjadi degradasi mutu beton yang besar, sehingga perlu ditetapkan karakteristik dan kategori sampai kondisi beton terburuk untuk kebutuhan penilaian kondisi beton.

CALCULATION OF THE BENDING ELEMENTS WITH ALLOWANCE FOR THE PHYSICAL NONLINEARITY OF THE STRAIN

An algorithm of the reinforced binding elements calculation with allowance for the physical strain of concrete and reinforcement has been suggested. The three linear diagram of the concrete condition and the two linear of the tensile reinforcement that correspond to the recommended norms in Russia have been used. The task has been solved by the method of linear approximation. The finite difference method has been used at each approximation that allows to define the beam rigidity individually for each dot j =1,2 , dotted on the beam with some small spacing. A method of determining the deflection curve bending, the bending moment, the rigidity as well as the compression areas of the reinforcement suitable for any deformation of the concrete most tensile fabric from 0 to limiting value ε_b2 has been suggested. A solution for the continuous three-span beam has also been introduced.

Determination of the Influence of Carbonation of Concrete and Corrosion of Steel on Reinforced Concrete Condition

Almost all reinforced concrete structures which are exposed to weather effects are threatened by corrosion. The corrosion of steel elements in structures has an influence on lifetime these constructions and adversely affects their properties. However, the steel in concrete structures is protected against corrosion due to the properties of concrete such as high pH or impermeability, but if the concrete is of poor quality and his protective properties are insufficient the corrosion can occur. A problem causes the action of carbon dioxide which has the effect of lowering the pH below the critical value and thereby accelerating the corrosion.Non-destructive methods such as Impact-echo method offer the possibility of easy and quickly detection of initial damage of structure and thus can prevent the occurrence of permanent damage to the whole construction.This article describes the development of corrosion which is caused by carbonation of the concrete and supported by action of chlorides by using Impact-echo method. The paper presents results obtained on the reinforced concrete samples with one steel rod passing through the center. After carbonation concrete the samples were exposed accelerated controlled degradation in aqueous NaCl solution for 4 months.