The effect of cement modification on the rheological properties of cement paste

Experimental tests have determined the effect of slag, opoka (silica-calcite sedimentary rock), silica fume (SiO2) suspension, dolomite dust and sodium silicate solution (NaSS) together with the polycarboxylatether based plasticizing admixture on the yield stress and viscosity of Portland cement paste the rheological properties of which have been defined applying a rotational viscometer with co-axial cylinders. The tests have revealed that slag, opoka, silica fume suspension and dolomite dust added to cement paste by replacing 10% of Portland cement (by weight) have an effect on the yield stress and viscosity of the paste subject to the form and fineness of additive particles. When 10wt% of Portland cement is replaced with slag cement, the yield stress of Portland cement paste reduces by about 25.9%, and viscosity increases by about 3.5 times compared with the yield stress and viscosity of reference cement paste. The yield stress of Portland cement paste with 0.5% NaSS admixture increases insignificantly, and viscosity grows approximately twice compared with reference cement paste. The tests have also showed that the modifying admixtures of Portland cement paste enable to control the rheological properties of cement paste

Sustainability Aspects of Real Estate Development: Lithuanian Case Study of Sports and Entertainment Arenas

The principles of sustainability have become particularly important in the real estate and construction sector over the past decade. Despite extended efforts to evaluate the sustainability aspects of the real estate development, very few attempts have been exposed in the scientific literature pursuing integrating the investors and real estate developers’ responsibility for the local community, regional economy and environmental problems within their financial expectations. The paper presents methodology enabling evaluating the balance of real estate development sustainability and financial viability issues during the feasibility study process. The Model for Real Estate Investment Evaluation Based on Sustainable Development Aspects proposed by the authors was applied to the case study of Lithuanian sports and entertainment arenas. By using multi-criteria decision analysis sustainability assessment of multi-functional arenas was carried out which disclosed that positive sustainability effects lays down on the owner’s and operator’s monetary liabilities

New classification of construction companies: overhead costs aspect / Naujas statybos įmoni ųklasifikavimas: pridėtinių išlaidų aspektas

The traditional classification of construction companies depending on the number of employees is not appropriate when analysing the competitiveness of construction companies. The collected data of Lithuanian construction companies was analysed by applying statistical methods and the construction companies were classified into competitiveness classes according to the relative value of the overhead costs. The new classification provides the basis for economical evaluation of the construction companies and modelling of their competitiveness in regard to the value of overhead costs as well as applying the competitive advantages for the estimation of construction bidding price. Santrauka Tradicinė statybos įmonių klasifikacija pagal įmonės darbuotojų skaičių nėra korektiška statybos įmonėms analizuoti ir jų konkurencingumui vertinti. Taikant statistinius duomenų apdorojimo metodus išnagrinėti Lietuvos statybos įmonių duomenys ir pasiūlyta nauja statybos įmonių klasifikacija į konkurencingumo klases pagal jų pridėtinių išlaidų santykinio rodiklio reikšmę. Sukurta nauja statybosį monių klasifikacija leidžia atlikti ekonominį statybos įmonių įvertinimą ir modeliuoti jų konkurencingumą pridėtinių išlaidų aspektu, suformuoti konkurencingą pasiūlymo kainą, įvertinant konkrečius statybos įmonės konkurencinius pranašumus. Reikšminiai žodžiai: konkurencingumas, pridėtinės išlaidos, įmonių klasifikavimas, statybosį mon