Abstract
The statistical phase method was introduced to achieve optimal mixing controlled low-strength material (CLSM) proportions, utilising statistical studies. There is no well-known explicit formulation for predicting hardened properties (in terms of unconfined compressive strength (UCS)) of CLSM. The proposed approach to optimising CLSM mix design is demonstrated in the most common case where experimental mixing was considered in compliance with the full factorial experimental design involving three variables with two levels (2<sup>3</sup>) and the Box-Wilson central composite design (CCD) method. Twenty CLSMs with six replicates (one hundred and twenty specimens) were considered in changing the levels of the main factors that affect CLSM compression strength, the water/cementitious ratio (2.53-2.73) and the wastepaper ash (WSA) percentage (50-100%) and cementitious materials content (160-200 kg/m<sup>3</sup>). The experimental results were used to analyse variance and design a UCS polynomial regression equation for design factors considered in this research. In order to emphasise how to optimise CLSM mixtures with different options, a statistical model was developed.
Highlights
Due to the rapid consumption driven by cities' development, the quantity of waste produced is rising significantly every year, and this increasing waste production is creating severe environmental problems
In ensuring that adequate experimental data are produced to obtain a regression model designed for unconfined compressive strength (UCS) that possible to apply to optimise the mixture proportions, selection of the levels of three main mixture design variables, comprising cm (WSA) content, w/cm ratio, and total cm content that mainly impact the performance of controlled low-strength material (CLSM) will be made
The influence of wastepaper sludge ash (WSA)% on UCS was found to be insignificant since it varied in a small range of 50 to 100%, it was included in the regression scrutiny because cement is still an essential raw material in the produce of CLSM
Summary
Due to the rapid consumption driven by cities' development, the quantity of waste produced is rising significantly every year, and this increasing waste production is creating severe environmental problems. The sets of trials were conducted, sampling and testing were carried out, and normal statistical techniques were used to analyse the experiment results Such approaches comprise analytical models for each performance criterion that match the results. Statistical techniques still require a solid number of experimental works; the added benefit is that uncertainty (variability) can characterise the expected (response) properties It has significant implications for specification and making cost-effective concrete mixtures [21,47,48,49,50]. Efforts were made to demonstrate using the proposed statistical approach to achieve optimal CLSM mix ratios using data obtained through experimental design, considering the w/cm ratio, the percentage of WSA, and the cm as factors. Considering the various options, the application of compressive strength models to optimise mixing design is illustrated
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