Slump Test: A New Empirical Model for High Yield Stress Materials

In order to decrease the fitting deviation between rheometrical measurements and empirical parameters using slump test, this paper proposes a new analytical method to evaluate the high yield stress of materials (cement pastes).In doing so, an experimental study was performed for measuring the empirical characteristics by cylindrical mold with different water to binder ratios (w/b) by aiming to increase the yield stress. Parallelly, experimental observations showed clearly the unyielded zone at flow stoppage of high yield stress samples. Based on these results, an idea was formed to applied metallic element at inlet of mold in order to push the spreading of paste. The obtained results of the model proposed in this paper were compared with the yield stress evaluated from shear flow curves using AR2000-rheometer with plate-plate geometry at rate-controlled. In fact, this study demonstrates the applicability and novelty of the present model in the process of relating the empirical parameters to yield stress.

Kekuatan Awal, Workability dan Berat Volume Beton berbahan Agregat Plastik Polypropylene

Eksploitasi plastik menyebabkan penumpukan limbah plastik semakin meningkat. Penggunaan limbah plastik pada beton dapat berkontribusi pada pengurangan limbah plastik di dunia. Dalam penelitian plastik polypropylene dimanfaatkan sebagai subtitusi parsial agregat halus. Penelitian ini bertujuan untuk menganalisa beberapa property fisis dan mekanis beton yang menggunakan limbah palstik sebagai subtitusi agregat halus. kuat tekan , workability dan berat volume menjadi variable utama yang akan diukur. Hasil dari penelitian ini menunjukkan bahwa pemakaian Plastik polypropylene sebagai pengganti agregat halus 10%, 20%, 30%, dan 40%, menghasilkan slump test sebesar 8,1 cm, 8,4 cm, 8,6 cm, dan 8,8 cm, dianggap masih memenuhi standar nasional indonesia. Hasil dari berat volume beton didapatkan sebesar 2211.46 kg/m3, 2138.21 kg/m3, 2105.73 kg/m3, dan 2021.65 kg/m3. Hasil Untuk kuat tekan pada 7 Hari didapatkan sebesar 9.12 MPa, 8.704 MPa, 8.5 MPa, dan 7.85 MPa.

Investigation of the Effect of using Salak Seeds as Coarse Aggregate in Concrete

This study described the effect of using salak seed waste as a substitute for coarse aggregate. The percentage of salak seed in concrete mixture became experimental variable to discover the best compressive strength of concrete. Quantitative study with experimental study was carried out at the Laboratory of Materials and Concrete, Faculty of Engineering, University. The design of experiment used a designed compressive strength of concrete of 20 Mpa. The experiment consisted of five variations in the percentage of salak seeds, namely 0%, 5%, 10%, 15%, and 20%. The slump test is carried out immediately after mixing the concrete in each proportion. Furthermore, 20 pieces of cylindrical concrete samples in each treatment were tested for 7,14,21 and 28 days. This method aims to compare the strength of each of the resulting concrete compositions. The results obtained showed that the use of salak seeds with a percentage of 5% and 10% gave a compressive strength value of 28 days which met the standard compressive strength of the design female. Meanwhile, the percentage of salak seeds 15% and 20% did not produce the planned compressive strength value. Therefore, salak seeds are suitable to be used as a substitute for coarse aggregate with a percentage of less than 10%. The higher the substitution of the mixture in the salak seed concrete, the lower the compressive strength of the concrete. The results of this study can be developed in green concrete studies that use waste.

Uji Eksperimental Penggunaan Zat Additif Mastersure 1007 Terhadap Workobility Dan Waktu Ikat Beton

Penggunaan bahan tambah pada beton merupakan suatu inovasi yang dapat berkembang sesuai kebutuhan dalam penggunaan beton pada pekerjaan kontruksi. Penggunaan bahan tambah ditujukan untuk mengubah ataupun memperbaiki sifat beton agar sesuai dengan kebutuhan dan pekerjaan tertentu seperti mempercepat dan memperlambat pengikatan dan mempermudah pekerjaan (workability). Untuk mengatasi permasalahan dilapangan jarak tempuh yang jauh yang mampu memperlambat waktu ikat semen dapat digunakan Jenis bahan tambah yang digunakan bersifat kimiawi (chemical admixture), dalam hal ini bahan tambah (admixture) MasterSure® 1007 Tipe G, yang mana kandungan Retarder lebih dominan daripada Superplasticiser. Tujuan penelitian ini untuk mengetahui pengaruh penambahan MasterSure® 1007 dalam campuran beton terhadap nilai slump dan waktu ikat beton. Metode penelitian yang digunakan merupakan metode eksperimental, dengan cara membuat benda uji (sampel). Benda uji yang menggunakan bahan tambah MasterSure® 1007 sebesar 0,8%, 0,9%, 1%, 1,1%, 1,2%, 1,3% dan 1,4% dari berat semen sesuai dengan Job Mix Design. Pengujian pada penelitian adalah penggujian Slump Test dan Penetration Test. Hasil penelitian menunjukkan bahwa pada variasi penambahan MasterSure 1007 dari dosis terkecil yaitu 0,8% sampai dosis terbesar yaitu 1,4% rata-rata mempunyai nilai slump optimum pada umur 3 jam pengecoran. Pada umur 4 jam pengecoran dapat dilihat bahwa semua variasi mengalami penurunan slump dikarenakan reaksi retarder pada zat additif MasterSure 1007 sudah mulai habis. Hal ini menyebabkan zat additif MasterSure 1007 yang memiliki kandungan superplasticizer mulai bekerja sehingga mempercepat hidrasi semen pada beton. Hasil penetrasi test didapatkan pada variasi Beton normal, 0,8%, sampai 1,4% masing-masing yaitu waktu pengikatan awal dari 75menit;150 lbs/in2, 360menit;120lbs/in2, 360 menit;170lbs/in2, 420menit;160lbs/in2, 540menit;120lbs/in2,720 menit;120lbs/in2 dan pengikatan akhir dan pengikatan akhir masing-masing 150 menit; 700lbs/in2, 540 menit; 700lbs/in2, 600 menit; 700lbs/in2, 720 menit; 700lbs/in2, 840 menit;700;bs/in2,1080 menit ; 700lbs/in2

Slump Test versus Straight Leg Raise Test in the Diagnosing of Lumbar Disc Herniation: A Prospective Comparative Study

Background: The clinical examination is one of the best suitable methods for diagnosis of low backache. Backache is one disease that the signs, clinical examination finding, and the results on imaging modalities not always related. The straight leg raising (SLR) and slump tests, can be used for diagnosis of lumber disc herniation. Objectives: To compare the result of the slump test and SLR test in the diagnosis of lumber disc herniation. Subjects and Methods: A prospective comparative study conducts on 280 patients in Al-Kindy teaching and private clinics complaints of backache, aging between 18-70 years old with acute or recurrent backache, sciatica pain, or low back and sciatica pain for last 12 weeks, while patients with spinal surgery, sacroiliac joints pain, cervical dysfunction and hip and knee pathology, and chronic illness were excluded. MRI of the lumbar region was done and clinically examine first by SLR test then Slump test on the next days by separated author. All the record collected patient’s data are interpreted with the MRI finding by the third doctor. Results: The Slump test is significant than the SLR in the patients with disc herniation at L4-L5 and (L4-5 &L5S1) 93.1% versus 70%, while for L5S1 level no significant in both tests. Leg pain present in 74.1 %, low back and leg pain in 21.5%, and only 4.4% present with low back only. Conclusion: The Slump test is more sensitive than the SLR test in diagnosis of lumber disc herniation.

Estudo da viabilidade na utilização de resíduos de construção e demolição (rcd) para produção de argamassa e concreto não estrutural no Distrito Federal - Brasília

A busca por alternativas que visam a redução dos impactos ambientais causados pelo descarte inadequado dos resíduos de construção e demolição vem ganhando maior destaque dentro das empresas e instituições acadêmicas ligadas à construção civil. Uma das alternativas estudadas, trata-se do uso do agregado reciclado na produção de argamassa e concreto. Buscando avaliar a utilização de resíduos de construção e demolição como agregado reciclado, a presente pesquisa teve como objetivo analisar o comportamento físico e mecânico do concreto não estrutural e da argamassa produzidos com agregados reciclados. Para argamassa foram desenvolvidos 2 traços: traço de referência (sem substituição) e traço com 100% de substituição do agregado miúdo por agregado reciclado. Para o concreto não estrutural foram desenvolvidos 3 traços: traço de referência (sem substituição); com 100% de substituição do agregado miúdo por material reciclado e com substituição de 100% de agregado miúdo e agregado graúdo por material reciclado. Foram moldados 12 corpos de provas cilíndricos, com 100 mm de diâmetro e 200 mm de altura, para todos os traços de concreto e 9 corpos de prova prismáticos, para cada um dos traços de argamassa. A partir da revisão da literatura e dos ensaios laboratoriais, foram realizados os ensaios de: caracterização dos materiais; do concreto: desempenho mecânico (resistências à compressão, à tração por compressão diametral); Desempenho físico (consistência de abatimento do tronco cônico - slump test e absorção de água por imersão, índice de vazios e massa específica); e da argamassa: desempenho mecânico (resistências à compressão e à tração na flexão); desempenho físico (índice de consistência, densidade de massa e teor de ar incorporado) seguindo todas as normas vigentes. Diante dos resultados alcançados, o concreto confeccionado com substituição total dos agregados naturais por agregados reciclados, apresentou resultados satisfatórios, destacando-se para a resistência a compressão, 27% maior que a obtida pelo concreto referência. Entre as argamassas, a confeccionada com agregado miúdo reciclado, obteve uma resistência a compressão, na idade de 28 dias, 20,3 % maior em comparação a argamassa confeccionada com agregado miúdo natural.

KUAT TEKAN DAN TARIK BETON DAUR ULANG YANG DIBUAT DARI BONGKARAN BETON PERKERASAN KAKU JALAN SEBAGAI AGREGAT KASAR: STUDI EKSPERIMENTAL

ABSTRAKBeton daur ulang merupakan campuran dari agregat kasar atau agregat halus daur ulang. Salah satunya dibuat dari hasil bongkaran pelat beton perkesaran kaku jalan (rigid pavement). Pembongkaran ini disebabkan oleh kerusakan, keretakan dan keausan pada perkerasan kaku yang diakibatkan oleh beban kendaraan. Bongkaran beton tersebut seringkali dibuang di sembarangan tempat atau hanya menjadi bahan urugan saja. Hal ini tidak menguntungkan, sehingga pada penelitian ini, bongkaran perkerasan kaku tersebut dijadikan sebagai agregat daur ulang. Pemanfaatan bongkaran beton ini merupakan perkembangan material beton, namun belum umum digunakan untuk material perkerasan kaku. Oleh karena itu, penelitian ini memanfaatkan bongkaran beton tersebut sebagai bahan baku beton dan diuji secara eksperimental untuk mendapatkan sifat fisik dan mekanik beton daur ulang. Hasil pengujian laboratorium menunjukkan bahwa persentase kadar air dan berat jenis agregat daur ulang lebih kecil dari agregat alam atau batu pecah, namun persentase abrasi dan penyerapan air atau porositas lebih besar dari pada agregat alam. Selanjutnya, agregat daur ulang tersebut digunakan sebagai pengganti agregat kasar alam dengan variasi 0, 25, 50, 75 dan 100%, dan kuat tekan rencana beton 20, 25 dan 30 Mpa. Hasil uji slump sebagai salah satu jenis uji beton segar mengalami penurunan, karena adanya peningkatkan kandungan agregat daur ulang, yaitu 2,17 – 15,74 %. Begitu juga penurunan hasil uji berat volume yaitu 0.88 – 9,28%, nilai kuat tekan beton adalah 3.7 - 25,7% dan tarik beton adalah 21,90 – 65,22%. Hal ini diakibatkan oleh peningkatan nilai persentase abrasi dan penyerapan air pada agregat daur ulang. ABSTRACTRecycled concrete is a mixture from recycled coarse or fine aggregate. One of them is made from demolished of road rigid pavement of concrete slab. It is coused by to damage, cracks and abrasion on the rigid pavement that is caused by vehicle loaded. The concrete demolished is often dumped in the any places or becomes fill material only. It has not benefited, so in this research, demolished of rigid pavement is made as a recycled aggregate. Utilization of this demolished concrete is a concrete material development, but it is not used commonly for rigid pavement material yet. Therefore, this research was use concrete demolished as raw material of concrete and it is tested experimentally to obtain the physical and mechanical properties of recycle concrete. Laboratory test result of water content percentage and specific gravity of recycled aggregate are smaller than natural aggregate or crush rock, but abrasion and water absorption or porosity percentage are greater than natural aggregate. Furthermore, the recycled aggregate is used as a substitute for natural coarse aggregate which variations of 0, 25, 50, 75 and 100%, and concrete compressive strength design is 20, 25 and 30 MPa. Result of the slump test as false The slump test as a kind of fresh concrete test does decrease when increasing the recycled aggregate content, that is 2 -16,%.. Likewise, decreasing of concrete weight volume is 0.88 – 9,28%, concrete compressive test results us 3.7 - 25,7% and concrete tensile strength is 21,90 – 65,22%. Those are caused by increasing abrasion and water absorption percentage of recycled aggregate.