Behaviour of Normal Concrete Us ing Superplasticizer under Different Curing Regimes
The performance of concrete primarily depends upon the type and ratio of its constituents, compaction, curing conditions and admixtures used during curing process. Part of this research emphasis to calculate the consequences on strength of concrete when water-cement ratio is constant and the increase in slump occurs with the increase in amount of superplasticizer by percentage. The rest of the investigation is carried out to study the effects of superplasticizer with different dosages under different curing regimes at an ambient field temperature ranges between 45°C-50°C. For this purpose, a concrete mix at 20MPa with all parameters constant was prepared by using an ASTM C494 type A, and F, anionic melamine polycondensate non-toxic superplasticizer with no chlorides. Different dosages of superplasticizer were used in different batches of all 95 specimens, and cured under different curing conditions and then tested for compressive and tensile strengths following ASTM standards. In all cases, th e water curing up to 28 days testing showed maximum strength. The highest and lowest values of compressive strength were obtained with the addition of 0.5% and 1% superplasticizer respectively. It was found that without increasing the W/C ratio, the addition of superplasticizer exhibits increase in strength.
Superplasticizing Additive Material on Concrete Performance and Effect on Concrete Performance in the Self-Locating Concrete Production: Literature Review
This survey presents a literature review on the superplasticizing additive material on concrete performance and effect on concrete performance in the self-locating concrete production with given a literature review and survey. That done through spotlight on the concrete and its properties, as well as, clarify the effect of chemical additives on fresh and hardened of the concrete. Explain the importance of superplasticizing additive material, and clarify the effect of adding material on concrete performance. The study concluded that substantial improvement in the concrete properties after use of the superplasticizer with high range water reducer, superplasticizer has given results that are more promising. Keywords : Concrete; Superplasticizing; performance; properties; and effect.
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.