Optimization of the Physical and Mechanical Properties of Grouting Material for Non-Soil-Squeezing PHC Pipe Pile

The physical and mechanical properties of grouting materials greatly affect the friction resistance and the bearing performance of a non-soil-squeezing PHC pipe pile. Orthogonal tests for four factors at five levels were carried out to optimize the proportion of the water–cement mixture by using Portland cement as a raw material and a water-reducing agent, expansion agent and early-strength agent as additives. The following conclusions were obtained: (1) Both the water–cement ratio and the dosage of water-reducing agent are positively correlated with the fluidity of the water–cement mixture and have the greatest influence on the fluidity, followed by the expansion agent and early-strength agent. The saturation point of the water-reducing agent is 1.5%. (2) The strength of the grouting body decreases linearly with the increase of the water–cement ratio, and the dosage of the water-reducing agent has no obvious effect on the strength. As the dosage of expansion agent increases, the strength of the grouting body decreases rapidly. The expansion agent mainly plays a key role in the middle and late stages of the hardening process of the slurry. Early-strength agents have a greater impact on the early strength, but less on the later strength. When the slurry is solidified for 3 h, the early-strength agent has the greatest impact on the strength with an optimal dosage of 5%. (3) The volume of the grouting body has an inverse relationship with the water–cement ratio, and the optimal amount of expansion agent is 12%. The incorporation of an expansion agent makes the volume increase of the grouting body exceed the volume shrinkage ratio caused by the hardening of the grouting body with a curing time of more than 3 days, ensuring a slight increase in the volume of the grouting body. After 3 days, even though the effect of the expansion agent is gradually weakened, it can still ensure that the volume of the grouting body does not shrink. With the increase of the amount of water-reducing agent, the volume of the grouting body gradually decreases. When the amount of water-reducing agent exceeds 1.5%, the volume of the grouting body no longer decreases. (4) The early-strength agent has almost no effect on the volume of the grouting body. When the curing time is 3 h, the water–cement ratio has the greatest influence on the volume of the grouting body, followed by the water-reducing agent, and, finally, the expansion agent. After 3 h, the water–cement ratio still has the greatest influence, and the influence of the expansion agent gradually exceeds that of the water-reducing agent. The water-reducing agent mainly affects the volume of the grouting body in the water separation stage, and the expansion agent mainly plays a role in the middle and late stages of the slurry solidification. After optimized ratio analysis, the fluidity of the water–cement mixture can be improved, the volume shrinkage ratio rate can be lowered and the early strength can be increased.

Optimizing Flexural Strength of Concrete Fc’ 14,5 MPa Using Acetylene Welding Carbide Waste

Replacing the main material using unused materials such as hazardous waste can be utilized in concrete innovation. One of the hazardous wastes that can utilize the waste generated from the acetylene welding process. The waste has hardening properties when exposed to water. Its properties are almost the same as cement can replace or add part of the cement mixture. Conducted this research was to determine the effect of using carbide waste from the acetylene welding process on the flexural strength of concrete. The experimental method is carried out by making test objects in the laboratory. The proportions of waste added were 7%, 10%, and 12% by weight of cement. The test object used is in the form of a beam with dimensions of 60 cm x 15 cm x 15 cm. The planned initial quality is concrete F'c 14.5 MPa (K175). The flexural strength test was carried out at the age of 27 days of concrete. From the results of the research carried out, it is found that the use of carbide waste from the acetylene welding process has not been able to improve the quality of concrete significantly. The highest flexural strength was obtained from waste at 7%, with a flexural strength value of 9.692 Mpa. So from these results, it can be used as a reference in the utilization of carbide waste from the acetylene welding process.

Economic Evaluation of Cement Grouted Bituminous Mixes for Airport Pavements

The Cement Grouted Bituminous Mix (CGBM) is an innovative material that could be used to build airport pavements subjected to heavy concentrated loads or fuel and solvent leaks. CGBM is composed of a porous asphalt clogged with an expansive cement mixture, which fills the asphalt voids. This paper focuses on two airport pavements (i.e., a taxiway and a helipad one) to be paved in an Italian airport. For each surface, the construction and maintenance costs of a CGBM pavement and a traditional flexible pavement have been compared. The pavements should bear different traffic loads, while the weather, subgrade, and materials are the same: the fatigue and rutting verification gives structures whose cost analysis leads to different results. The CGBM solution for the taxiway has a cost comparable to that of the equivalent traditional flexible pavement (i.e., 73.87 €/m2 vs. 73.20 €/m2 during the service life). On the other hand, the overall discounted cost of the helipad surface paved with CGBM is higher than that obtained for the traditional pavement (i.e., 82.4 €/m2 vs. 67.5 €/m2). Therefore, the study demonstrates that the economic opportunity of CGBM solutions strongly depends on traffic loads.

The use of plant materials for the synthesis of superplasticizer

The paper presents data on the synthesis of phloroglucinol-furfural modifier (1,3,5-trihydroxybenzene-2-furaldehyde oligomer) based on 2-furaldehyde (furfural) and 1,3,5-trihydroxybenzene (phloroglucinol). The synthesis of a modifier with different molar ratios of phloroglucinol/furfural was carried out. It was found that an increase in the molar ratio leads to an increase in the plasticizing ability of the modifier. The optimal concentration of the catalyst was determined to be equal to 50% by weight of phloroglucinol. Two chemical forms of the modifier were obtained: H-form and Na-form. The structure of various forms of the modifier has been studied by scanning electron microscopy. It was found that the oligomers used in the work for the synthesis of the modifier, in addition to 2-furyl methyl alcohol, do not have plasticizing properties. Purified 2-furyl methyl alcohol has weak plasticizing properties. It is shown that to achieve the best plasticizing effect, it is necessary to gradually introduce a condensing agent into the reaction mixture. With gradual introduction, a complete condensation reaction occurs between the monomers, which affects the improvement of the plasticizing properties of the resulting product. The spread of the cement mixture when using 0.3% of the additive based on the mass of cement in terms of dry matter is 19 cm.

The Effect of Polymer Powder on the Cracking of the Subbase Layer Composed of Cold Recycled Bitumen Emulsion Mixtures

The research was aimed at assessing the effect of the redispersible polymer powder on the fracture resistance of a subbase made of a mineral–cement mixture with a bitumen emulsion. The test was performed at two temperatures, i.e., 0 °C and 20 °C. The prepared mixtures differed in the content of cement, asphalt emulsion, and polymer modifier. Cement and redispersible polymer powder were dosed in 1.5% steps from 0.5% to 3.5% while the amount of bitumen emulsion ranged from 0.0% to 5.0%. The SCB (semi-circular bending) tests carried out in the laboratory showed the dependence of the influence of the amount of binder and polymer modifier on the fracture resistance of the recycled subbase. Mixes containing a polymer modifier in their composition are characterized by a much higher resistance to cracking than traditional mineral–cement–emulsion mixtures. An example is the doubling of the framework’s fracture toughness (KIC) when the amount of the polymer modifier is increased from 0.5% to 2.0% with a constant cement content of 0.5%. The obtained results (KIC) in this case were 2.90 and 5.81. The key is the right ratio of polymer powder and cement in the base composition.

Bond Strength Analysis of Repaired Concrete based on Polymerization of Glycoluril Formaldehyde

Repairing old concrete include the correct choice of material and methodology adopted which may not affect the quality providing monolithic condition for old and new concrete. This study investigates two different parameters such as the impact as well as the optimum usage of new polymer glycoluril-formaldehyde as bonding material. Second one is about to understand the surface preparation for increased bonding strength at the interfacial area of old and new concrete. Five different types of surface textures are used to estimate the bond strength such as plane, lined, waved, grid and chipped. Glycoluril aids as a bonding material in both old and new concrete, and it is introduced at 0%, 1%, 2%, 3%, and 4% into the cement mixture. When the surface preparation creates a rough surface, it helps in repairing the concrete with the help of polymerization of glycoluril formaldehyde which promotes the enhancement of bond strength and slant shear. The bond strength of the specimens was measured by slant shear method in compression as well as tension for a period of 1, 2 and 4 weeks of new concrete. The results indicated that the highest bond strength was achieved in 3 percentage addition of glycoluril and grid patten substrate preparation.