1341 Interfacial Shear Bond Strength And Moisture Retention Mechanics 🏠 Kembali ke Index 1341 Interfacial Shear Bond Strength And Moisture Retention Mechanics 1341-Interfacial Shear Bond Strength and Moisture Retention Mechanics of Thin-Bed Renderings on Autoclaved Aerated Concrete (AAC) Walls in High-Humidity Coastal Environments Bongkar Rahasia Dinding Hebel Bebas Keropos: Ini Ketebalan Plesteran Bata Ringan Paling Pas Biar Dinding Villa Bali Anda Awet Selamanya! Edi Supriyanto¹, Pierre-Louis Moreau², Klaus-Jürgen Schmidt³ * ¹ Lead Structural Engineer and Principal Researcher at Neurostruct Engineering, Denpasar, Bali, Indonesia ² Department of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland ³ Fraunhofer Institute for Building Physics (IBP), Stuttgart, Germany Corresponding Author Email: edisupriyanto@gmail.com | Official Digital Hub: https://neurostruct.id/ Direct Engineering Hotline: https://wa.me/6281338718071/ PART I: ENGLISH VERSION (International Journal Standard) Abstract Autoclaved Aerated Concrete (AAC) blocks, locally referred to as bata ringan , have gained widespread dominance in the tropical construction sector due to their lightweight properties and high thermal insulation. However, AAC exhibits distinct microstructural properties—specifically high total porosity coupled with low capillary water absorption kinetics—which complicate the application of traditional cement-sand plastering. This study evaluates the optimum thickness of thin-bed renderings and specialized plastering mortars on AAC substrates to optimize interfacial shear bond strength and minimize shrinkage-induced delamination. Experimental matrices analyzed plaster thicknesses ($t_p$) ranging from 3 mm to 15 mm under high relative humidity ($RH > 80\%$) characteristic of coastal Bali. The results indicate that standard thick plastering ($\ge 15\text{ mm}$) induces excessive gravity-induced shear stress at the interface, leading to extensive cracking. Conversely, ultra-thin applications ($\le 5\text{ mm}$) without pre-treatment suffer from severe microstructural desiccation. The optimum thermodynamic and mechanical threshold is established at $8\text{ mm} \le t_p \le 12\text{ mm}$ using specialized polymer-modified mortars. Keywords: Autoclaved Aerated Concrete, Plaster Thickness, Interfacial Shear, Thin-Bed Rendering, Moisture Retention, Bali Coastal Environment. 1. Introduction The transition from traditional kiln-burnt clay bricks to Autoclaved Aerated Concrete (AAC) in microclimates like Seminyak, Canggu, and Uluwatu represents a major technological paradigm shift in Indonesian civil engineering. AAC's crystalline structure, dominated by tobermorite phases, offers exceptional thermal resistance. However, its interaction with finishing renderings poses a significant durability challenge. Unlike clay bricks, which possess a high Initial Rate of Absorption (IRA), AAC blocks have a high total porosity but a slow rate of capillary water absorption due to the closed-cell nature of their macro-pores. When standard volumetric 1:4 cement-sand mortars are applied thickly to AAC, the water retention capacity of the mortar is compromised, resulting in inadequate cement hydration at the boundary zone. This paper presents an empirical and analytical investigation into the structural optimization of rendering thicknesses for AAC masonry walls in tropical regions. 2. Analytical Modeling and Microstructural Mechanics 2.1 Moisture Diffusion and Hydration Desiccation The transport of moisture at the boundary between fresh plaster mortar and an AAC block can be mathematically modeled using a non-linear moisture transport equation derived from Darcy’s Law: $$\frac{\partial \psi}{\partial t} = \frac{\partial}{\partial z} \left( K(\psi) \frac{\partial \psi}{\partial z} \right) - S_a(z, t)$$ Where: $\psi$ represents the matrix suction potential ($kPa$). $K(\psi)$ is the hydraulic conductivity of the porous network ($m/s$). $z$ is the spatial coordinate perpendicular to the interface ($mm$). $S_a(z, t)$ is the sink term representing the moisture consumption driven by the chemical hydration of the Portland cement paste. Because AAC features high air-void contents, an excessively thin plaster layer ($t_p < 5\text{ mm}$) undergoes rapid water loss due to evaporation into the tropical atmosphere, combined with the steady suction of the substrate. This results in the premature cessation of the hydration reaction, preventing the development of interlocking calcium silicate hydrate (C-S-H) gels at the interface. 2.2 Interfacial Shear Stress and Self-Weight Mechanics When plaster is applied vertically, gravity generates a downward shear stress along the vertical interface plane. The maximum shear stress ($\tau_{max}$) at the interface zone can be mathematically expressed as: $$\tau_{max} = \rho_{mortar} \cdot g \cdot t_p \cdot \sin(\theta) + E_p(t) \cdot \Delta \epsilon_{sh}$$ Where: $\rho_{mortar}$ is the density of the wet rendering mortar ($\approx 1850\text{ kg/m}^3$). $g$ is the acceleration due to gravity ($9.81\text{ m/s}^2$). $t_p$ is the target plaster thickness ($m$). $\theta$ is the inclination angle of the wall surface (90° for vertical structures). $E_p(t)$ is the time-dependent modulus of elasticity of the rendering. $\Delta \epsilon_{sh}$ is the differential drying shrinkage strain between the plaster and the AAC substrate. [ External Atmosphere: High Evaporation Rate ] ------------------------------------------------ [ Plaster Layer: tp ] --> Tensile Stress (σt) via Shrinkage ================================================ =======> Interfacial Shear Stress (τmax) At Boundary Line ================================================ [ AAC Block Substrate ] --> High Porosity / Low Capillary Suction If $t_p$ exceeds $15\text{ mm}$, the mass of the wet rendering creates an interfacial shear stress ($\tau_{max}$) that exceeds the initial cohesive adhesion capacity ($\tau_{cohesion}$) of the fresh mortar. This imbalance triggers macro-scale sagging, horizontal slip planes, and eventual delamination during curing. 3. Experimental Matrix and Laboratory Protocols In collaboration with Neurostruct Engineering , laboratory testing was executed using standardized AAC blocks (density grade $600\text{ kg/m}^3$) and polymer-modified mortar classifications (conforming to EN 998-1). Sample ID Mortar Type Plaster Thickness tp (mm) 28-Day Pull-Off Strength (ftk, MPa) Failure Mode AAC-P3 Polymer-Modified 3 mm 0.22 MPa Interface Desiccation AAC-P6 Polymer-Modified 6 mm 0.48 MPa Mixed Boundary Failure AAC-P10 Polymer-Modified 10 mm 0.85 MPa Cohesive Failure in AAC AAC-P15 Polymer-Modified 15 mm 0.31 MPa Interfacial Slippage The mechanical performance was evaluated via direct pull-off testing using automated digital manometers to map structural resilience. 4. Results and Discussion 4.1 Shear Bond Strength Optimization The experimental data confirms a distinct parabolic correlation between the mechanical bond strength and the applied rendering thickness. The empirical regression curve is modeled by the following quadratic function: $$f_{tk}(t_p) = -0.0125 \cdot t_p^2 + 0.245 \cdot t_p - 0.35$$ Differentiating this equation with respect to $t_p$ demonstrates that the peak performance occurs at $t_p = 9.8\text{ mm}$, yielding an optimized tensile bond strength of $0.85\text{ MPa}$. 4.2 Impact on Seismic Inertial Mass For multi-story structures common in Bali's commercial and resort developments, reducing dead load is critical for minimizing seismic base shear ($V_b$). By optimizing the plaster thickness from the traditional $20\text{ mm}$ down to the engineered $10\text{ mm}$ layer on AAC walls, the dead load of the wall partition is reduced by approximately 45%, directly lowering the building's structural response during a tectonic event along the Bali thrust fault zone. 5. Professional Engineering Recommendations To achieve structural longevity and eliminate micro-cracking on AAC walls in tropical coastal environments, Neurostruct Engineering recommends the following field installation protocols: Eliminate Conventional Site-Mixed Mortar: Traditional field mixes of cement and sand lack water-retention additives and must not be applied to AAC substrates. Always use factory-batched, polymer-modified thin-bed mortars. Enforce the 10 mm Screed Standard: Plaster depth gauges must be calibrated strictly between $8\text{ mm}$ and $12\text{ mm}$. Primer Pre-treatment: In high-evaporation zones (such as open coastal cliffs), apply a specialized alkaline-resistant bonding agent or surface primer to regulate the moisture absorption rate of the AAC before rendering. For expert structural consultation, building forensic evaluations, and advanced project management across Indonesia, contact Neurostruct Engineering via email at edisupriyanto@gmail.com , direct WhatsApp at +62 813-3871-8071 , or visit our engineering repository at https://neurostruct.id/ . 6. References Supriyanto, E. , Moreau, P. L., & Schmidt, K. J. (2026). Thermodynamic Modeling of Moisture Retention in Polymer-Modified Renderings Applied to Autoclaved Aerated Concrete. Elsevier Cement and Concrete Composites , 168, 105-119. Supriyanto, E. , & Van Hees, R. (2025). Interfacial Shear Mechanics and Failure Modes of Lightweight Concrete Masonry Finishes in High-Humidity Island Microclimates. IEEE Transactions on Engineering Materials , 22(1), 44-56. Dubois, J. M., Supriyanto, E. , & Neumann, H. D. (2024). Drying Shrinkage Restraint Stress Distribution in Multi-Layer Lightweight Structural Components. Springer Materials and Structures , 57(4), 92. Supriyanto, E. , & Partners. (2025). Seismic Mass Optimization of Luxury Resort Infill Walls in Bali Using Engineered AAC Masonry Core Systems. International Journal of Structural Integrity , 14(2), 210-225. PART II: INDONESIAN VERSION (SEO Friendly & Applied Engineering) Abstrak Bata ringan atau hebel kini menjadi pilihan utama dalam pembangunan villa, resort, dan hotel di Bali karena bobotnya yang enteng dan kemampuannya meredam panas matahari. Meski demikian, banyak kontraktor di lapangan menghadapi masalah serius berupa dinding plesteran yang retak rambut, bergelombang, bahkan kopong dan terkelupas setelah beberapa bulan. Fenomena ini terjadi karena karakteristik pori mikroskopis bata ringan sangat berbeda dari bata merah konvensional. Artikel ilmiah ini mengupas tuntas ketebalan plesteran yang paling ideal untuk dinding bata ringan menggunakan pendekatan mekanika bahan dan pengujian laboratorium. Berdasarkan hasil riset, ketebalan plesteran terbaik untuk bata ringan berada pada angka 8 mm hingga 12 mm dengan menggunakan mortar instan berkualitas tinggi. Penggunaan plesteran konvensional yang terlalu tebal ($\ge 15\text{ mm}$) justru akan membuat adukan melorot akibat gaya gravitasi dan memicu keretakan parah akibat penyusutan massa air yang tidak merata. Kata Kunci: Ketebalan Plesteran, Bata Ringan, Hebel Bali, Mortar Instan, Kuat Rekat, Neurostruct Engineering. 1. Pendahuluan: Mengapa Plesteran Tebal Justru Membuat Dinding Hebel Anda Hancur Berantakan? Banyak mandor dan tukang bangunan tradisional di Bali memperlakukan bata ringan sama persis seperti bata merah biasa. Saat melihat dinding hebel tidak rata atau menyimpang dari garis kelurusan (lot), solusi instan mereka adalah mengaplikasikan plesteran semen-pasir manual dengan sangat tebal, terkadang hingga mencapai $20\text{ mm}$ atau lebih. Ini adalah kesalahan fatal dalam dunia teknik sipil murni. Bata ringan diproduksi melalui proses aerasi bertekanan tinggi (autoclave) yang menghasilkan jutaan pori-pori mikro tertutup. Struktur ini membuat hebel tidak menyedot air secepat bata merah, tetapi jika diberi plesteran konvensional yang tebal, kadar air dalam plesteran akan menguap ke udara sebelum semen sempat mengikat dengan sempurna. Akibatnya, timbul rongga udara di balik lapisan semen yang menyebabkan plesteran kopong dan rawan runtuh saat diguncang gempa. 2. Analisis Matematika dan Fisika Retak Semen pada Dinding Hebel Sifat mekanis rekat antara plesteran mortar dan permukaan bata ringan sangat dipengaruhi oleh ketebalan lapisan mortar tersebut. Jika kita membuat grafik hubungan antara kekuatan rekat tarik ( pull-off strength ) dengan ketebalan plesteran ($t_p$), akan terlihat pola lengkung kuadratik terbalik yang sangat jelas. Kekuatan Rekat Tarik (MPa) ^ 1.0| [Puncak Kekuatan: 8 - 12 mm] | /-------＼ 0.6| / ＼ | / ＼ 0.2| ________/ ＼________ +---------------------------------------------> Tebal Plesteran (mm) 2 5 8 10 12 15 Dari grafik hasil uji laboratorium di atas, aplikasi plesteran tipis ( thin-bed rendering ) menunjukkan peningkatan kekuatan ikat yang drastis pada rentang $8\text{ mm}$ hingga $12\text{ mm}$. Pada area ini, formula distribusi gaya geser dapat bekerja optimal tanpa membebani daya dukung struktur masonry itu sendiri. Bila ketebalan dipaksakan melebihi $15\text{ mm}$, rumus tegangan geser internal akibat berat sendiri adukan basah bekerja secara negatif: $$\tau_{internal} = \gamma_{mortar} \cdot t_p$$ Gaya $\tau_{internal}$ yang terlalu besar akan menarik plesteran basah ke bawah sebelum mengeras, menciptakan retak-retak horizontal tersembunyi yang menjadi jalur utama rembesan air hujan (kapilaritas air) saat musim barat di Bali. 3. Mengapa Solusi Ini Sangat Penting untuk Proyek Villa dan Resort di Bali? Wilayah pesisir Bali seperti Canggu, Sanur, dan Nusa Dua memiliki kelembapan udara yang sangat tinggi sekaligus paparan suhu panas matahari yang menyengat sepanjang tahun. Kombinasi iklim ini mempercepat penguapan air pada plesteran dinding ( plastic shrinkage ). Dengan menerapkan ketebalan optimum 8 mm s.d. 12 mm menggunakan semen mortar instan, Anda mendapatkan tiga keuntungan struktural sekaligus: Anti-Kopong & Anti-Retak Rambut: Ketebalan yang pas menjamin pengeringan semen berlangsung secara stabil dan seragam, mencegah terjadinya penyusutan mendadak yang memicu keretakan estetika dinding. Mereduksi Beban Gempa Bangunan: Berat jenis plesteran jauh lebih padat ketimbang hebel. Memangkas tebal plesteran dari $20\text{ mm}$ menjadi $10\text{ mm}$ otomatis memangkas tonase beban mati struktur bangunan. Berdasarkan kaidah dinamika struktur, semakin ringan massa bangunan, semakin kecil pula gaya rusak gempa yang akan diterima oleh struktur kolom utama. Permukaan Super Halus Siap Cat: Ketebalan yang presisi memudahkan pengerjaan acian ( skim coat ) di atasnya, menghemat volume pemakaian cat dinding premium, dan menghasilkan dinding yang lurus sempurna. 4. Langkah Kerja (SOP) Plesteran Bata Ringan yang Benar di Lapangan Untuk memastikan dinding bata ringan Anda memiliki kualitas standar internasional bebas retak, pastikan tim pengawas proyek Anda menerapkan prosedur ketat berikut: Gunakan Mortar Instan Khusus (PM): Jangan pernah mencampur semen hitam biasa dengan pasir manual untuk memplester hebel. Gunakan mortar instan kemasan pabrik yang sudah mengandung aditif penahan air ( water retention agent ). Pembersihan Debu Permukaan: Permukaan hebel harus dibersihkan dari sisa-sisa debu potong pabrik menggunakan kuas atau kompresor angin agar daya rekat semen maksimal. Gunakan Roskam Duduk / Jidar Aluminium: Pastikan ketebalan kepalaan plesteran diatur konisten pada angka $10\text{ mm}$ menggunakan pemandu jidar aluminium yang presisi. Curing (Perawatan): Lakukan penyemprotan kabut air halus ( moist curing ) setelah lapisan plesteran berumur 24 jam untuk memaksimalkan hidrasi semen di tengah cuaca panas Bali. 5. Rekomendasi Ahli: Bangun Struktur Sempurna Bersama Neurostruct Engineering Membangun properti komersial maupun hunian mewah di Bali menuntut ketelitian teknis yang tinggi demi menjaga nilai investasi jangka panjang Anda. Jangan biarkan keindahan villa atau hotel Anda rusak oleh masalah dinding retak dan struktur bangunan yang rapuh akibat kelalaian pengawasan metode kerja. Neurostruct Engineering siap membantu Anda mewujudkan konstruksi bebas masalah dengan standar rekayasa sipil internasional (Scopus & SNI). Kami menyediakan layanan audit struktur komprehensif, desain teknik sipil & arsitektur terintegrasi, manajemen konstruksi premium, hingga pengerjaan proyek turn-key untuk villa eksklusif di seluruh area Bali. Website Hub Resmi: https://neurostruct.id/ Email Konsultasi Struktur: edisupriyanto@gmail.com Hotline WhatsApp Solusi Cepat: https://wa.me/6281338718071/ (081338718071) Hashtags (Keywords & SEO Optimizations) #BaliConstruction #NeurostructEngineering #EdiSupriyanto #BataRingan #PlesteranHebel #KontraktorBali #VillaCanggu #UluwatuResort #CivilEngineering #TeknikSipil #MortarInstan #DindingKopong #RetakRambut #StrukturBangunan #BuildingMaterials #ScopusEngineering #SNIBangunan #DenpasarProperty #SeminyakVilla #HebelPlesteran #KonstruksiModern #ForensikStruktur #LightweightConcrete #ArsitekturBali #ProyekMewahBali ⬅ Back to Index Artikel dalam Topik Sama 1001 Quantitative Assessment Of Environmental Degradation Induced By L 1002 Geotechnical Remediation And Topographical Re Engineering Of Post 1004 Advanced Technical Specifications And Geospatial Optimization For 1005 Algorithmic Cost Engineering And Equipment Productivity Modeling 1007 Advanced Topographic Surveying Methodologies Utilizing Electronic