Sand is one of the most abundant, naturally occurring materials in many parts of the world, which is used in local rural areas in infrastructure projects such as in the construction of low volume paved and unpaved road layers due to their availability at low cost and scarcity of other suitable construction materials. Several geotechnical solutions for sand stabilization have been undertaken to improve their properties in order to overcome erosion, failure of pavements under traffic loading, embankments, cuts and excavations caused by failures of sand structure. In this investigation, bentonite clay–water slurry was used due to its cohesive and eco-friendly nature to improve sand strength by the means of manual injection in the laboratory and pilot scales. Sand was stabilized using variation of bentonite clay contents, 0%, 1%, 2%, 3%, and 4% (by weight of dry sand), at different curing times: 0 days, 1 day, 2 days, and 3 days. Direct shear tests were conducted to determine shear strength parameters for sand before and after stabilization process. Furthermore, a transparent polypropylene box (60 cm × 40 cm × 30 cm) was used in this study as a larger scale for sand stabilization technique by applying manual grouting of bentonite clay–water slurry to the sand mass. A mechanical shaker was used at 100, 200, 300, and 400 rpm for 10 min at each stage to test the stability of sand in addition to using a Scanning Electron Microscope (SEM) to obtain images for stabilized sand and Ground Penetrating Radar (GPR) to scan soil mass before and after stabilization. The test results showed that a slurry composed of 3% of bentonite clay additive with 10.3% added water by weight of dry sand mass are the optimum amounts for the stabilization process, which provides a substantial resistance to shear forces.

This study aimed to investigate the effect of freeze and thaw (FT) cycles on the performance of asphalt concrete (AC) mixtures modified by partial replacement of mineral filler of the aggregate with natural bentonite clay (NBC) in order to reduce damage that occurs due to rapid FT cycles within the pavement structure. After exposure to FT cycles, AC mixture stability is reduced and becomes lower than minimum requirements, which leads to earlier damage of pavement. In order to enhance the AC mixture’s abilities to sustain severe FT cycles, this study used NBC amounts as a substitute for mineral filler by weight of its portion of the total aggregate: 5%, 10%, 15%, and 20%. Marshall stability, flow, and FT cycles were tested, and interior damage degree was assessed by a nondestructive test called ultrasonic pulse velocity (UPV). The results revealed the viability of combining NBC with asphalt mixtures for the purpose of improving the mixtures’ properties, particularly in environments where asphalt pavement is exposed to alternating FT cycles. The results also revealed that replacement of filler with NBC by 5% in AC mixtures reduced the damage caused over 8 continuous weeks of rapid FT cycles by 13%, which, in future applications, would reduce maintenance cost and prolong the pavement’s service life.

This study aimed to investigate the performance of asphalt mixtures after natural bentonite clay partial replacement of mineral filler portion of aggregates. Different bentonite contents were used to replace the mineral filler by total weight of its portion of total aggregates, namely, 5, 10, 15, and 20%; additional bentonite contents were conducted for the stability test, namely, 25 and 30%. Marshall stability, flow, bulk density, hydraulic conductivity, and indirect tensile strength (ITS) tests were performed. Results showed that replacing mineral filler by natural bentonite clay in asphalt mixtures leads to the increase of density and stability, which increased to 11.57 kN for mixtures containing 15% bentonite (compared with 9.17 kN for the control specimen), with 23% loss when soaked with water for 24 h. Results indicate an increase in both flow and ITS values and reduction in hydraulic conductivity of the modified mixtures compared with control specimens.

The mechanical strength, mass loss and dynamic elastic modulus of Portland cement concrete incorporating recycled glass powder (GP) as a cement replacement material or crushed glass aggregate (GA) as a fine aggregate replacement material subjected to different cycles of freezing and thawing were investigated. A series of 11 concrete mixing proportions was designed with a constant water/cement ratio of 0·5 including fractions of GP or GA. Tests were conducted on 100 × 100 × 100 mm cubes, 100 × 200 mm cylinders and 100 × 100 × 500 mm prisms. The tests of compressive strength, flexural strength and indirect tension were used to examine the impact of the inclusion of different percentages of glass (GP or GA) on the mechanical properties of concrete cured for 7, 28 and 60 d. Two non-destructive testing approaches (ultrasonic pulse velocity and resonance frequency) were used in the freezing and thawing test. The test results indicated that, compared with conventional concrete, the mechanical strength characteristics of concrete containing GP or GA were more enhanced. The use of GP decreased the deterioration of the concrete under the effect of frost action, whereas the use of GA had an adverse influence on the frost resistance of the concrete.

The aim of this study is to produce durable self-compacting concrete (SCC) using different fractions of recycled steel slag aggregates (SSA) by replacing natural aggregate. For this purpose, a series of nine mixing proportions were designed with a constant water-to-cement ratio of 0.34 and a change of SSA ratio replacing natural coarse or fine aggregates by weight from 0 to 50% (increments of 12.5%). For freshly mixed SCC, the flowability, passing and filling abilities, segregation and viscosity were observed by slump flow, slump-flow time (T₅₀₀), L-box and V-funnel empirical tests. Mechanical properties were tested for compressive and flexural strengths, while the durability characteristics were conducted for water absorption and permeability, sulfate attack and freeze–thaw action (F/T). Non-destructive measurement approaches (i.e. ultrasonic pulse velocity and resonance frequency) were involved in the F/T testing. The test results indicate that the incorporation of SSA in SCC is suitable and improves the mechanical strength and durability properties, and that enhancement is more pronounced at higher SSA increments, especially when replacing the coarse natural aggregate partially by coarse SSA.