Faculty of Engineering

Permanent URI for this communityhttps://rda.sliit.lk/handle/123456789/4203

Browse

Filters

2022 - 20253

Advanced Search

Filter by

Settings

Subject: search.filters.subject.Compressive strength

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    PublicationEmbargo
    Mechanical and durability analysis of eco-friendly light weight cement blocks using raw rice husk as a partial replacement for manufactured sand
    (Elsevier Ltd, 2025-03-08) Thavarajah, L; Sundaralingam, K; Tharmarajah, G
    The study investigates the mechanical and durability properties of cement blocks made by partially replacing manufactured sand (M-sand) with raw rice husk (RRH). The rising demand for sand in construction, coupled with the environmental impact of its extraction, has prompted the exploration of alternative materials. RRH, a byproduct of rice milling, offers an eco-friendly substitute for sand. The research examines blocks containing varying proportions of RRH (20 %, 40 %, and 60 %) and compares treated and untreated husks. Key parameters, including compressive strength, tensile strength, density, performance when exposed to heat, and water absorption, were analyzed. The results show that up to 40 % of RRH can be used to replace sand without compromising the blocks' structural integrity. Treated RRH blocks demonstrated better bonding with cement, leading to higher compressive and tensile strengths compared to untreated ones. A 40 % RRH replacement achieved an average compressive strength of 3.57 MPa, surpassing the minimum requirements for non-load-bearing masonry units as per Sri Lankan and Australian standards. However, increasing RRH content to 60 % significantly reduced strength and durability. Additionally, RRH blocks exhibited a decrease in density, offering advantages in terms of transportation and handling. Water absorption increased with higher RRH content due to its porous nature yet remained within acceptable limits for treated blocks. These findings suggest that RRH can be a sustainable alternative to sand in masonry applications, especially in rural and eco-conscious construction.
  • Thumbnail Image
    PublicationOpen Access
    The Properties of Lime/Soil Concrete
    (SLIIT, 2022-02-11) Perera, J; Chandrasiri, J
    The investigation of materials for replacing cement in concrete manufacturing has garnered steady interest from experts in recent years. However, the majority of past researches have only focused on the use of lime as a cement substitute in producing Lime Concrete. The reason for this is that lime concrete can be made easily and cheaply while still providing a durable material that can minimize negative environmental impacts. Even though lime is used as an alternative material the integration of a new material as a replacement for conventional aggregates has been limited. As a result, this study will attempt to examine the various compositions of hydraulic lime as a partial replacement of cement while completely replacing the coarse and fine aggregate with a soil to find the influence on the physical characteristics of Lime/Soil concrete. This will also help in decreasing the ecological imbalance caused due to the excess use of conventional aggregates. Locally available reddish-brown laterite soil was used in this study without any modifications. C30 concrete mixes containing 0%, 10%, 15% of hydraulic lime replaced with OPC and complete replacement of aggregate with laterite soil were casted before subjected to water curing. Workability, compressive strength, splitting tensile strength and water absorption test were conducted in accordance with the existing standard. Based on the results obtained from the study it has shown that even with complete replacement of aggregate with laterite soil it was able to produce workable concrete with satisfactory strength that can be employed for ground improvements in pavement design and to manufacture economical non-load bearing concrete blocks. The targeted strength still can be achieved with replacement of 15% hydraulic lime for a lower cost. With the accomplishment from the composition, future studies will be able to better assess the long-term effects of construction operations on the environment.
  • Thumbnail Image
    PublicationOpen Access
    A novel approach to explain the black-box nature of machine learning in compressive strength predictions of concrete using Shapley additive explanations (SHAP)
    (Elsevier, 2022-04) Ekanayake, I.U; Meddage, D. P. P; Rathnayake, U
    Machine learning (ML) techniques are often employed for the accurate prediction of the compressive strength of concrete. Despite higher accuracy, previous ML models failed to interpret the rationale behind predictions. Model interpretability is essential to appeal to the interest of domain experts. Therefore, overcoming research gaps identified, this research study proposes a way to predict the compressive strength of concrete using supervised ML algorithms (Decision tree, Extra tree, Adaptive boost (AdaBoost), Extreme gradient boost (XGBoost), Light gradient boosting method (LGBM), and Laplacian Kernel Ridge Regression (LKRR). Alternatively, SHapley Additive exPlainations (SHAP) – a novel black-box interpretation approach - was employed to elucidate the predictions. The comparison revealed that tree-based algorithms and LKRR provide acceptable accuracy for compressive strength predictions. Moreover, XGBoost and LKRR algorithms evinced superior performance (R ¼ 0.98). According to SHAP interpretation, XGBoost predictions capture complex relationships among the constituents. On the other hand, SHAP provides unified measures on feature importance and the impact of a variable for a prediction. Interestingly, SHAP interpretations were in accordance with what is generally observed in the compressive behavior of concrete, thus validating the causality of ML predictions.