Waste tyres accumulate very quickly in a landfill as a result of the fast development of the transport industry, and mainly automobiles. The polymeric waste has limited usage and is rarely employed in a highly economic and viable product. A rigid pavement material needs to have high mechanical properties and durability when exposed to aggressive environments. In this research, a combination of waste tyre with rice husk ash and Portland Cement Composite (PCC) as a primary binder was designed to produce concrete that meets the requirements of flexural strength value of the rigid pavement based on the Indonesian Standard from Bina Marga 2018. Eight mixes with a variety of water/cement ratio (0.30-0.40), crumb rubber (2.5-7.5%), and rice husk ash (7.5-10%) were designed in this research. The control mix was PCC concrete. The crumb rubber substituted the fine aggregate content, while the rice husk ash replaced the cement content in concrete. The specimens were cast and subsequently cured in water pond up to 28 days. The mechanical properties of concrete, namely compressive strength and flexural strength were determined for all variations. Based on the results, Mix 1 with w/c ratio of 0.30, crumb rubber of 5%, and rice husk ash of 10%, performed both the highest compressive strength and flexural strength values of 36.38 MPa and 4.53 MPa, respectively, after 28 days. Both values fulfilled the requirements of the Indonesian Standard Bina Marga 2018. It can be concluded that an appropriate combination of crumb rubber and rice husk ash improves the mechanical properties of the concrete and has potential as a rigid pavement material.
Fly ash is a hazardous and toxic waste material from burning coal. However, it can be used as a material of geopolymer concrete because it contains high amounts of silica and alumina. Recent research on geopolymer concrete is still being conducted because it is part of green building material. This review aims to determine and analyzed the durability of fly ash geopolymer hybrid concrete in aggressive environments. The environment studied included seawater, sulfuric acid, and elevated temperature. OPC concrete is a high calcium material; therefore it is susceptible to aggressive environments compared with OPC concrete, geopolymer concrete contains aluminosilicate and low calcium material, which is not reactive with aggressive environment. The method used in this study is a literature review of several relevant research sources, and data were collected and analyzed. The results showed that fly ash geopolymer hybrid concrete had increase compressive strength compared to OPC concrete. In the seawater environment, the compressive strength of geopolymer concrete increases from 10%-15%. The compressive strength of geopolymer concrete also increases in a sulfuric acid environment up to 360 days of test age, and it is resistant to fire up until 800 °C. Likewise, the porosity of the geopolymer fly ash concrete decreased while the OPC concrete increased. According to the analysis and discussion results, it was resumed that fly ash geopolymer concrete is more environmentally friendly and durable than OPC concrete, especially in seawater, sulfuric acid, and post-fire environments.
<p>Peatlands have an important role in ecosystems as a carbon storage and helps to reduce greenhouse gas emissions.Inappropriate peatland conversion causes common problems such as forest fires which create severe air pollution and trigger the production of greenhouse gases due to the release of stored carbon. As a result, early education regarding peat soil conservation is necessary to ensure that people understand the importance of peat soil and the harm that happens when peatlands are converted inappropriately. This program aims to educate students about peatlands and raise awareness about the importance of protecting and conserving peat from an early age. Educational materials are delivered using creative books containing illustrated stories, important knowledge about peat, and interactive games to attract student’s interest in reading and make information easier to recall. The results of the final evaluation through a questionnaire revealed that using creative books to educate students about peatlands was successful in improving students' understanding of peatlands. This is proven by the increasing number of students who fully understand the peat information that has been taught from 3 students to 32 out of 33 students.</p><p><strong>BAHASA INDONESIA ABSTRAK</strong>: Salah satu peran penting lahan gambut bagi ekosistem adalah sebagai pengikat karbon sehingga bermanfaat dalam mengurangi gas rumah kaca. Pengalihfungsian lahan gambut dengan cara yang tidak benar menyebabkan timbulnya masalah yang umum terjadi seperti kebakaran lahan gambut yang menyebabkan pencemaran udara melalui polusi kabut asap dan memicu terbentuknya gas rumah kaca akibat pelepasan karbon yang disimpannya. Untuk itu, pemberian edukasi mengenai pelestarian tanah gambut perlu diterapkan sejak dini agar masyarakat mengetahui peranan penting tanah gambut dan kerusakan yang terjadi apabila lahan gambut dialihfungsikan. Pengabdian ini bertujuan untuk memberikan edukasi pengenalan lahan gambut sekaligus meningkatkan kepedulian untuk menjaga dan melestarikan gambut sejak dini. Materi edukasi disampaikan menggunakan buku kreatif yang berisi cerita bergambar, pengetahuan penting tentang gambut, dan <em>games</em> interaktif agar menarik minat membaca dan membuat informasi menjadi lebih mudah diingat oleh siswa. Hasil evaluasi akhir melalui kuisoner menunjukkan bahwa pemberian edukasi tentang tanah gambut menggunakan media buku kreatif berhasil meningkatkan pemahaman siswa mengenai lahan gambut yang dibuktikan dengan bertambahnya jumlah siswa yang telah paham sepenuhnya mengenai materi gambut yang telah diajarkan dari semula 3 siswa menjadi 32 dari 33 siswa.</p>
Abstract. Two-stage concrete (TSC) is a sustainable concrete which is produced by forcing a flowable cement grout mixture through the voids of a skeletal mass made of compacted preplaced aggregates. From the technical and economic aspects, TSC is particularly useful for construction and repair of concrete structures especially foundations, underwater construction, nuclear reactors, concrete dams, heritage structures and in constructions with closely spaced reinforcement. TSC differs from ordinary concrete in that it contains a higher proportion of stone aggregate and the aggregate stays in point-to-point contact as placed. Thus, the mechanical characteristics of the TSC in failure conditions are distinctly different from ordinary concrete. This paper presents the results of experimental investigations conducted to evaluate the compressive, tensile strength and modulus of elasticity of TSC using grouts with different water-to-cement ratios and admixture contents. It was found that the modulus of elasticity and splitting tensile strength of TSC are equivalent or higher than that of conventional concrete at the same compressive strength. In this method of construction, the splitting tensile strength can be conservatively estimated using the American concrete institute (ACI) equation for conventional concrete.
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