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Lime and/or Ordinary Portland cement (OPC) are the traditional binders used in soft soil 17 stabilisation. However, their manufacture has a negative impact on the environment. This 18 paper reports the results of experimental work for the optimisation of a binary blended 19 cementitious binder (BBCB) using two types of fly ash as an alternative for use in soft soil 20 stabilisation. The optimum content of the high calcium fly ash (HCFA) was initially 21 determined along with the effect of grinding activation on the performance of HCFA. 22 Subsequently, the effect of palm oil fuel ash (POFA) pozzolanic reactivity on the engineering 23 properties of soft soil, stabilised with HCFA, was investigated by producing different binary 24 mixtures of HCFA and POFA. Based on the Atterberg limits and unconfined compressive 25 strength (UCS) tests, the combination of POFA with HCFA results in a considerably lower 26 plasticity index (PI) and higher compressive strength than those obtained from the soil treated 27 with HCFA alone. Substantial changes in the microstructure and binders of the stabilised soil 28 over curing time were evidenced by SEM imaging and XRD analysis. A solid and coherent 29 *Revised manuscript with no changes marked Click here to view linked References structure was achieved after treatment with BBCB as evidenced by the formation of C-S-H, 30 portlandite and ettringite as well as secondary calcite.

Soil stabilisation using traditional binders such as Ordinary Portland Cement (OPC), has a serious negative environmental impact, specifically carbon dioxide (CO 2) emissions as a result of the manufacture of OPC. Because of this, the use of sustainable binders has become a critical issue to help reduce cement production through the use of by-product materials. This research seeks to develop a new ternary blended cementitious binder (TBCB) to replace cement for soft soil stabilisation. Different ternary mixtures containing wastes i.e., high calcium fly ash (HCFA), palm oil fuel ash (POFA) and rice husk ash (RHA) along with flue gas desulphurisation (FGD) gypsum used as a sulphate activator and grinding agent, were examined. The results illustrate that ternary mixtures improved the engineering and mechanical properties of stabilised soil. The results indicated that the plasticity index (PI) was reduced ACCEPTED MANUSCRIPT from 20.2 to 13.0 and the unconfined compressive strength (UCS) increased after 28 days of curing from 202kPa to 944kPa using the optimum non-FGD activated mixture. FGD contributed significantly by increasing the UCS to 1464kPa at 180 days of curing, which surpassed that for the reference cement (1450kPa), and by improving the soil consistency limits; where the PI decreased to 11.7 using TBCB compared with 14.5 for the soil treated with the reference cement. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed substantial changes in the diffraction patterns and microstructure components of the TBCB paste over the curing period, confirming the formation of cementitious products. A solid, coherent and compacted structure was achieved after treatment with TBCB as evidenced by the formation of C-S-H, CH and ettringite.

This study aims to investigate the effect of cement replacement with high volume fraction of ground granulated blast furnace slag (GGBFS) and cement kiln dust (CKD) on mechanical, durability and microstructural properties of cement mortar from 1day to 550 days. Compressive strength and ultrasonic pulse velocity (UPV) were used to evaluate the mortars' performance.Besides, statistical analyses were conducted to predict mortars' mechanical and durability performance as well as investigate the influence of mortars' properties (mixture and curing time) on their performance. The results indicated that replacing the cement with up to 60% GGBFS and CKD showed a comparable behavior to the cement after 28 days of curing onward.The statistical analysis revealed that the developed models achieved high level of agreement between the predicted and observed results with a coefficient of determination (R 2 ) of more than 0.97. The findings in this study announced on the development of promising binder that can be used in different construction sectors with the benefits of reducing the CO2 emissions.

The development in the construction sector and population growth requires an increase in the consumption of construction materials, mainly concrete. Cement is the binder in concrete, so increasing cement production will increase the energy consumed, as well as in the emission of carbon dioxide. This harmful effect of the environment led to the search for alternative materials for cement, as the waste or by-products of other industries is a promising solution in this case. Among these common materials are ground granulated blast furnace slag (GGBS) and cement kiln dust (CKD). This dataset describes the compressive strength and ultrasonic pulse velocity of mortar consisted of high content of GGBS and CKD combinations as a partial substitute for cement (up to 80%) at the ages of 1, 2, 3, 7, 14, 21, 28, 56, 90 and 550 days. This dataset can help the researchers to understand the behaviour of GGBS and CKD in high replacement levels for cement during early (1 day) and later ages (550 days). According to this understanding, the authors believe that the data available here can be used to produce more environmentally friendly mortar or concrete mixtures by significantly reducing the amount of cement used by replacing it with waste or by-products of other industries.

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Due to its significant deficiencies such as low permeability, low bearing and shear strength, and excessive compressibility, soft soil is one of the most problematic types of soil in civil engineering and soil stabilization can be considered a suitable technique for pavements. This study investigates the use of ground granulated blast slag (GGBS) and cement kiln dust (CKD) as stabilizers for soft soil. Thus, this study involves two optimization stages; in the first stage, GGBS was incorporated into 0%, 3%, 6%, 9%, and 12% by the weight of cement to obtain the optimal percentage, which was 6%. Then, the optimal GGBS was blended with CKD in a binary system at 0%, 25%, 50%, 75%, and 100% by the dry weight of the soil. The testing program used in this paper was Atterberg limits with compaction parameters to investigate the physical properties and unconfined compressive strength (USC) at 7 and 28 days to examine the mechanical characteristics. In addition, the microstructures of the soil specimens were tested at 7 and 28 days using scanning electron microscopy (SEM). The findings reveal that the binary system enhanced the physical and mechanical properties of the soft soil. The optimum binder achieved in this study was 6% (25% GGBS and 75% CKD), which generates an increase in strength of about 3.3 times in 7 days, and of 5.5 times in 28 days in comparison to the untreated soil. The enhancement was attributed to the formation of the hydration products as approved by SEM. Consequently, in the case of soft subgrade soils, this technique can increase the pavement’s bearing capacity and performance.

This research aims to stabilize clayey soil utilizing fluid catalytic cracking with an unchangeable ordinary portland cement ratio of 3 percent. A soft clayey soil was blended with 1.5, 3, 4.5, and 6 percent of fluid catalytic cracking by the dry stabilized soil weight, the ordinary portland cement amount has been fixed at 3 percent. The adding of different FCC ratios impact cement stabilized soil evaluated based on the results of unconfined-compressive-strengths test that gained after curing for 7 and 28 days. It was noticeable from the results that the best combination is the combination of soil remedied with 3 percent of each cement and FCC in improving the compressive strengths from 249.80 to 806.20k Pa for the stabilized soil after curing for 28 days. The most highlighting soil binder combination was analyzed utilizing scanning electron microscopy. It was noticed from the scanning electron microscopy results; cementitious materials were produced after 7 days of curing and improved more after curing for eight days.