Hydrolysis of organic sulfate esters proceeds by two distinct mechanisms, water attacking at either sulfur (S-O bond cleavage) or carbon (C-O bond cleavage). In primary and secondary alkyl sulfates, attack at carbon is favored, whereas in aromatic sulfates and sulfated sugars, attack at sulfur is preferred. This mechanistic distinction is mirrored in the classification of enzymes that catalyze ...

Utilization of pozzolanic materials (fly ash, slag, zeolite, metakaolin, microsilica and more) in the manufacturing of cement and concrete has increased considerably over the last decades. Another option is to use concrete containing sulfate resisting cement. This could help minimize the harmful impacts on concrete exposed to an aggressive environment. The issue of the deteriorative impact of t...

Applied electric fields , the reason behind stray currents, accelerate ingress of sulfate into cementitious materials . To identify mitigation approaches, this study investigates effects slag and fly ash on sodium attacks cement pastes under a constant current. The mineralogical alterations induced by were analyzed using X-ray diffractometry, thermogravimetric analysis scanning electron microsc...

Sulfate attack in concrete structures is considered to be among the major durability concerns in civil infrastructure systems. Proper modeling techniques can help us understand the influence of aggressive environments on the concrete performance more readily and accurately. Such an understanding improves the decision making process in every stage of construction and maintenance and will help in...

The substrate scope of inverting alkylsulfatase Pisa1 was extended towards benzylic sec-sulfate esters by suppression of competing non-enzymatic autohydrolysis by addition of dimethyl sulfoxide as co-solvent. Detailed investigation of the mechanism of autohydrolysis in 18O-labeled buffer by using an enantiopure sec-benzylic sulfate ester as substrate revealed that from the three possible pathwa...

In this study, waste ash was utilized as a pozzolanic material in blended Portland cement in order to reduce negative environmental effects and landfill volume required to dispose of waste ash. The influence of waste ash, namely palm oil fuel ash, rice husk ash and fly ash on compressive strength and sulfate resistance in mortar were studied and evaluated by some accelerated short-term techniqu...

Abstract Seawater sea-sand recycled concrete (SSRAC) is a new sort of green concrete, it has good environmental and economic benefits. In this paper, the dry-wet cycle full immersion erosion environments simulated. The change characteristics mechanical properties SSRAC under sulfate attack are studied compared with ordinary (OC) freshwater river sand (RAC). test shows that erosion, significantl...