Comparison of Data Mining Techniques for Predicting Compressive Strength of Environmentally Friendly Concrete

This research is funded by African Union Commission (AUC) and Japan International Cooperation Agency (JICA) Abstract Although concrete has good qualities that make it suitable for a wide range of applications in the construction industry, it also has undesirable properties; one of which is its low tensile strength. Numerous studies are being carried out to improve the undesirable features of concrete by using substitute materials such as industrial, manufacturing, agricultural as well as domestic wastes. In Africa, there is a pressing need for reusing and recycling waste materials. Following the extensive use of concrete in the vast construction industry, the incorporation of wastes like Polyethylene Terephthalate (PET) bottles and fly ash to improve its quality is a sensible intervention. PET bottles, used for packaging of beverages, and fly ash, generated during the combustion of coal, are causing severe environmental degradation. This study evaluated the effects of using PET fibres and fly ash on the performance of concrete. PET fibres with an aspect ratio of 50 (100mm length and 2mm width) were incorporated in the concrete mix at percentages of 0.5, 1.0 and 1.5% by weight of cement. On the other hand, fly ash was introduced as a cement replacement at percentages of 20, 22.5, 25, 27.5 and 30% by weight of cement. The performance of the modified concrete was evaluated based on workability, compressive strength, and splitting tensile strength. The combination of 1.5% PET fibres and 27.5% fly ash resulted in 33.45% tensile strength improvements, while keeping the workability and compressive strength unaffected. Keywords: Concrete, polyethylene terephthalate; fly ash; ordinary Portland cement; aggregates; workability; compressive strength; splitting tensile strength; aspect ratio DOI : 10.7176/CER/11-6-05 Publication date :July 31 st 2019

The current socioeconomic demand requires adequate engineering performance and environmentally friendly materials from the perspective of sustainable development. The scarcity of conventional natural resources and the severe environmental consequences of extraction have prompted research into alternative materials and resources for use in the road industry. Based on the findings of the existing studies, this research aims to explore the suitability of alternative materials for road construction projects towards sustainability in Sri Lanka. A quantitative research strategy was employed in the current study, and the questionnaire was distributed among 44 professionals involved in different types of road projects. The collected data were analysed by using Relative Important Index (RII). 84% of respondents considered alternative sustainable construction materials are highly suitable for the construction of road elements. Bituminous materials, natural soil, crushed rock and cement concrete are mostly commonly traditional materials. Construction and demolition waste (C&D), fly ash, plastic waste, and waste rubber tires were selected as the best materials for base construction, cement kiln dust waste, fly ash, glass waste, and waste rubber for sub-base and C&D waste and glass waste for sub-grade construction. Alternative sustainable materials can solve the waste disposal issue, scarcity of natural materials, and cost savings. Thus, this study presents a collective listing of the most viable alternative materials already in use by the global industry, with the goal of establishing a noble notion for better incorporation of alternative sustainable materials into road construction in Sri Lanka.

The placement of conventional concrete mixtures in underwater construction results in a high percentage of material loss owing to washout of cement paste. The current paper presents the influence of antiwashout admixture (AWA) on various properties of concrete. Eleven self-flowing concrete (SFC) mixtures using type II cement were proportioned. A combination of low water–cement (w/c), high cement contents, AWAs, fly ash and silica fume were used to enhance the resistance of fresh concrete to washout. The concrete mixtures were proportioned to be highly flowable, self-levelling and cohesive. The w/c materials ratios ranged between 0·35 and 0·39, which corresponds to a typical underwater concrete mixture. The concrete mixtures were tested for slump, slump flow, washout resistance and compressive strength. The compressive strength of each concrete mixture cast under water was determined at 3, 7 and 28 days and compared with the compressive strength of the same concrete mixture cast under normal conditions (in air). Test results indicated that the use of an AWA facilitates the production of flowable concrete mixtures with the added benefit of lower washout loss. Concrete mixture proportioned using type II cement and fly ash at a 15% level of replacement was found to develop SFC that had better fresh and hardened properties and was more resistant to washout. The self-flowing underwater concretes developed 28-day compressive strengths ranging from 20 to 28 MPa.

Global warming and climate changes are the major environmental challenges globally. With CO2 emission being one of the main greenhouse gases emitted to the environment, and cement and concrete production amounting to about 10% of the global CO2 emission, there is a need for the construction industry to utilize an environmentally sustainable material as an alternative to cement. This study analyzed the cost, CO2 emission and strength properties of green self-compacting concrete (SCC) ternary blend containing fly ash, calcium carbide residue (CCR), and crumb rubber (CR) as a replacement material by volume of cement, cementitious material, and fine aggregate, respectively. Cement was replaced with fly ash at 0% and 40% by volume. CCR was used as a replacement at 5% and 10% by volume of cementitious materials, CR replaced fine aggregate in proportions of 10% and 20% by volume. The result indicated that the mix with 0% fly ash and 20% CR replacement of fine aggregate was the most expensive and had the highest CO2 emission. However, the mix with 10% CR, 40% fly ash, and 10% CCR had the lowest CO2 emission and was therefore the greenest SCC mix. The 28-day maximum compressive strength of 45 MPa was achieved in a mix with 0% CR, 0% fly ash, and 10% CCR, while the utmost 28-day splitting tensile strength of 4.1 MPa was achieved with a mix with 10% CR, 0% fly ash, and 5% CCR, and the highest flexural strength at 28 days was 6.7 MPa and was also obtained in a mix with 0% CR, 0% fly ash, and 5% CCR. In conclusion, a green SCC can be produced by substituting 40% cement with fly ash, 10% fine aggregate with CR, and 10% CCR as a replacement by volume of cementitious material, which is highly affordable and has an acceptable strength as recommended for conventional SCC.

Construction activities require concrete as a widely used material. Concrete consists of several compositions, namely fine aggregate, coarse aggregate, water, and Portland cement as the main material for the binder. Cement production contributes around 6% of carbon emissions which can damage the environment, including global warming, and the use of high levels of cement material in concrete mixtures, so alternative materials are needed to replace cement or cement additives for concrete mixes. Alternative materials used in this research are fly ash and silica fume. This research aims to determine the test results and characteristics of concrete using silica fume and fly ash as partial cement substitute materials as well as the effect of the ratio of silica fume and fly ash on the compressive strength of concrete. The research was carried out by direct testing in the laboratory. The various mixtures of Fly Ash (FA) and Silica Fume used are: FA 10% and SF 5%, FA 15% and SF 5%, FA 20% and SF 20%, FA 25% and SF 10%. Based on the results of compressive strength tests carried out at 28 days of concrete, it shows that the use of silica fume and fly ash to replace cement cannot be said to have succeeded in increasing the strength of the concrete. The highest compressive strength value was achieved by variation 3, namely with a fly ash content of 20% and 10% silica fume, producing a compressive strength value of 19.44 Mpa, this shows that the strength achieved is still limited to low quality concrete below 20 Mpa.

Self-compacting concrete (SCC) enhanced by the addition of a supplementary admixture of metakaolin and/or modifying agent rice husk ash has been the object of several types of research due to its display of different properties than normal vibrated concrete. This study aimed at utilizing machine learning approaches, viz, Support Vector Machine, Multilayer Perceptron, Gaussian Processes Regression, random tree, M5P tree, and Random Forest to develop models using seven input parameters, viz, cement (kg/m3), water (kg/m3), fine aggregates (kg/m3), coarse aggregates (kg/m3), superplasticizers (kg/m3), metakaolin (kg/m3), and rice husk ash (kg/m3) and one output parameter being the 28-day compressive strength (MPa) of SCC mix ratios derived from reliable literature. The dataset consisted of 159 mix ratios with their 28-day compressive strength. The results obtained for the dataset are subject to two different methodologies: the supplied test data method and the cross-validation method. The results obtained are compared and allowed users to make a reasonable prediction of compressive strength for mix ratios with the aid of models developed.

Flood susceptibility mapping using a novel ensemble weights-of-evidence and support vector machine models in GIS

Influence of cement type on ITZ porosity and chloride resistance of self-compacting concrete

Fly ash is widely used in the cement industry to improve the performance and durability of concrete. The future availability of fly ash, however, is a concern, as most countries are inclining towards renewable energy sources as opposed to fossil fuels. Additional concerns have been raised regarding the impact of strict environmental regulations on fly ash quality and variability. This paper, therefore, evaluates if nano calcium carbonate (nano CaCO3) can be used as an alternative to fly ash. This paper presents comprehensive testing results (fresh, hardened, and durability) for OPC (Ordinary Portland Cement) and PLC (Portland Limestone Cement) concretes with 1% nano CaCO3 and compares them to those for concretes with fly ash (both Class F and C). Compared to concretes with fly ash, OPC and PLC with nano CaCO3 presented improved testing results in most cases, including later age strength, permeability, and scaling resistance. As nanotechnology in concrete is a relatively new topic, more research on the efficient use of nanotechnology, such as for proper dispersion of nano CaCO3 in the concrete, has potential to offer increased benefits. Further, nano CaCO3 is environmentally and economically viable, as it has the potential to be produced within the cement plant while utilizing waste CO2 and generating economic revenue to the industry. Thus, nano CaCO3 has the potential to serve as an alternative to fly ash in all beneficial aspects—economic, environmental, and technical.

Self-compacting concrete with different levels of pulverized fuel ash

Self-compacting concrete (SCC) is a highly efficient concrete that can be compacted and formed under its own weight without external vibration. However, the constituents of SCC are many and they have diverse material properties. Hence, it is difficult to predict the working performance of SCC with a single factor regression relationship. Therefore, the artificial neural network (ANN) approach is chosen in the present work to simulate the relationship between proportions of constituents and properties of SCC. This paper aims at predicting properties of SCC containing fly ash based on the experimental data available from the literature. The eight input parameters in the proposed models include amounts of cement, water, water to powder ratio, binder, fly ash, coarse aggregate, fine aggregate, and superplasticizers. The four output parameters are V-funnel flow time, slump flow final spread diameter, compressive strength at 28 and 90 days. A procedure to select the number of hidden layer neurons is discussed. Moreover, the parametric analysis of the developed ANN model is conducted to evaluate the effect of input parameters on SCC properties. By comparing the estimated and experimental results, the proposed ANN model shows great potential in predicting the properties of SCC with different percentage volume fractions of fly ash.

The development of self-compacting concrete using alternative materials is expanding in recent years due to the technical and economic benefits of the mixture. This study focuses on the structural and compositional behavior of sodium hydroxide (NaOH)-activated fly ash based self-compacting concrete (SCC). Fly ash was partially replaced with Ordinary Portland Cement from 0–30%. The tests performed on concrete samples include workability, strength, microstructural, and impact resistance. The results showed that activated fly ash reduces the heat of the hydration process of the concrete mixture but enhances pozzolanic reactions, which led to increased strength properties. The addition of activated fly ash modifies the mineralogy of the concrete, as evident in strength characteristics. The best performance of the activated fly ash based SCC, in terms of strength, was found at 10–15% substitutions, which can somewhat reduce the cost of production of SCC and strength improvement advantage.

The feasibility of using a high volume of non-clinker binders in self-compacting concrete related to its basic engineering properties

This paper presents an extensive comparative analysis of the experimental results of chemical stabilisation of clayey soil in laboratory conditions by comparing the effects of adding conventional stabilisers (lime, cement binder), stabilisers that can be considered as waste material (fly ash, rock flour), as well as alternative chloride-based materials (ferric chloride, calcium chloride, potassium chloride) on the geomechanical properties of the soil. With the aim of determining the stabiliser optimal content in the mixture with the soil, in the first part of the research, the effects of stabilisation of clayey soil of medium plasticity using the considered stabilisers with different percentage share on the change in uniaxial compressive strength (UCS) and pH value of the soil at different time intervals after the treatment were analysed. In the second part of the research, additional tests were conducted on soil samples with optimal content for each of the considered stabilisers by monitoring changes in the physical and mechanical properties of the soil. These include Atterberg’s limits (liquid limit and plasticity limit), modulus of compressibility in the oedometer, California bearing ratio (CBR), and swelling potential at different time intervals after the chemical treatment to determine the durability of stabilisation effects. The results of the conducted research reveal that each of the conventional, waste, and alternative materials considered as chemical stabilisers contributes to the improvement of the geomechanical properties of the clayey soil, primarily in terms of increasing the bearing capacity and reducing the swelling of the treated soil.

Multiple mechanical properties prediction of hydraulic concrete in the form of combined damming by experimental data mining