Setting Time Of Binder Research Articles

Setting time of geopolymer binder based on Umeanyar slate stone powder

This study aims to determine the effect of precursor and activator proportion on the setting time of the geopolymer binder. The precursor used was Umeanyar slate stone powder containing SiO2 (49%), Al2O3 (11%), CaO (11.2%). While the activator used was a mixture of 14 M sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3). The proportion of precursor: activator (P/A) in the geopolymer binder were 70%: 30%; 75%: 25%; 80%: 20% and those of Na2SiO3 : NaOH (SS/SH) were 1:1; 1.5:1; 2:1, by weight. The setting time of the binders was tested according to the SNI 2049: 2015. Measurement of setting time using vicat test equipment and based on normal consistency. The measurement of the setting time was carried out every 15 minutes until the initial bonding time was reached. The initial and final setting time result of the geopolymer binder decreased to 75 minutes and 100 minutes when P/A, as well as, SS/SH increased.

КОМПОЗИЦИОННЫЕ ВЯЖУЩИЕ НА ОСНОВЕ БЕТОННОГО ЛОМА

The object of research is composite binders obtained from concrete scrap of destroyed buildings and structures for the production of various construction products and structures. Fractions of concrete scrap of 0,0–0,16 mm and 0,16–0,315 mm are used, since x-rayphase analysis of various fractions of concrete scrap shows that these fractions have the highest content of non-hydrated particles of alite and belite. The influence of the specific surface area on the normal density of cement dough and the setting time of binders is established. Comparative physical and mechanical indicators of hardening of binders with different specific surfaces indicate that the most stable results with a uniform increase in strength is the composition of a binder with a specific surface of 964 m2 / kg, with an increase in strength from 2 to 7 days – 27 % and from 7 to 28 days – 21 %. This binder is characterized by optimal strength at the age of 28 days – 25,5 MPa. With a specific surface of 964 m2/kg, the best conditions are created for the formation of the primary frame and its further fouling with various calcium crystalline hydrates, which ensure optimal density and strength. This composite binder has a specific surface area of 964 m2/kg and is more energyefficient. Composite binders obtained in a vibration mill from concrete scrap fractions (0,0–0,16 and 0,16–0,315 mm) meet the requirements of normative documentation on setting time and physico-mechanical parameters, which allows to recommend them for use as binders in the production of construction products and structures for various purposes.

Effects of Curing Temperature and MMA Content on the Working Life of MMA-Modified Vinyl Ester Polymer Concrete

The main purpose of this study is to identify the effects of curing temperature and methyl methacrylate (MMA) content on the working life of vinyl ester polymer concreteusing MMA as a monomer, N,N-dimethyl-p-toluidine (DMP) and methyl ethyl ketone peroxide (MEKPO) as initiators and cobalt naphthenate as a promoter. The results have shown that the working life of vinyl ester polymer concrete was shortened with an increased curing temperature and a decreased MMA content. Also, it was found that the curing temperature had a greater influence on the working life of vinyl ester polymer concrete than MMA content. The working life of vinyl ester polymer concrete was found to be about 70 and 10 min longer than the setting time of vinyl ester polymeric binder at curing temperatures of -10 and 20°C respectively. The MMA content had a much smaller effect on the curing temperature. Lastly, a linear regression equation was drawn by analyzing the correlation between setting time of the binder and working life of polymer concrete, which could be used for the prediction of the working life of vinyl ester polymer concrete based on the setting time of the vinyl ester binder.

Laser System for Testing Early Shrinkage of Concrete Elements in Conjuction with the Deterioration of the Setting Time

Abstract The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10x10x50cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was meant for the determination of changes in the length of thin-mortar. Simultanously measured were the changes of speed propagation of sound waves by Vikasonic, what allows to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting.

Factors affecting hazardous waste solidification/stabilization: A review

Solidification/stabilization is accepted as a well-established disposal technique for hazardous waste. As a result many different types of hazardous wastes are treated with different binders. The S/S products have different property from waste and binders individually. The effectiveness of S/S process is studied by physical, chemical and microstructural methods.This paper summarizes the effect of different waste stream such as heavy metals bearing sludge, filter cake, fly ash, and slag on the properties of cement and other binders. The factors affecting strength development is studied using mix designs, including metal bearing waste alters the hydration and setting time of binders. Pore structure depends on relative quantity of the constituents, cement hydration products and their reaction products with admixtures. Carbonation and additives can lead to strength improvement in waste–binder matrix.