Rate In Construction Industry Research Articles

Influence of cement on properties of calcined phosphogypsum based composite cementitious materials

Phosphogypsum is an industrial waste generated in the production of fertilizers causing environmental problems. Calcined phosphogypsum (CPG) is obtained by low-temperature calcination and dehydration of phosphogypsum. CPG is mainly used to produce building materials. However, mechanical strength properties and water resistance of CPG materials is extremely poor, which leads to its relatively low utilization rate in construction industry. To address this issue, various amount of Ordinary Portland cement (OPC), fly ash (FA), rice husk (RH) and modified admixtures (AD) were mixed with the CPG to obtain CPG-based composite cementitious materials, which enhanced the water resistance and mechanical strength of the corresponding hardened materials. The influence of different contents of cement on the setting time, hydration heat, hydration products, mechanical properties, water absorption, heavy metal leaching and deterioration coefficient of the composite cementitious material is investigated. The results showed that the optimal mixing ratio of CPG: OPC: FA: RH was 57: 20: 10: 13 considering the water resistance and mechanical strength properties of CPG-based composite cementitious materials. On these conditions, the compressive strength, the flexural strength, water absorption and deterioration coefficient of the specimens at 28 days are 6.1 MPa, 4.6 MPa, 29.4% and 0.66 respectively, which were in line with the national standard of phosphorus building gypsum wallboard. It was demonstrated that two skeleton types are present in the samples prepared using CPG-based composite cementitious materials, which had a synergistic support effect on the structure. The first skeleton was formed by gypsum dihydrate crystals (CaSO4·2H2O) and provided strength to the specimens at an early stage, while the second skeleton was formed by ettringite (AFt) and C–S–H gels, which provided strength at a later stage. The skeletons make the hardened materials denser and more waterproof. Moreover, the composite materials exhibited a positive solidification effect on heavy metals present in CPG.

Comparative Analysis of the National Fatality Rate in Construction Industry Using Time-Series Approach and Equivalent Evaluation Conditions.

Fatality rates such as fatalities per full-time equivalent workers are officially used to compare the risk level of the construction industry among various countries. However, each country evaluates the fatality rate using different conditions. This paper presents the comparison of fatality rates of various countries using conventional (national data) and pair (equivalent condition) methods through a time-series approach. The research was conducted in three stages. The risk level was evaluated in order in South Korea (1.54), Japan (0.84), Mexico (0.83), China (0.70), United Kingdom (0.15), and Singapore (0.13) in terms of national data. However, the risk level was re-evaluated in order in China (2.27), South Korea (2.05), Mexico (1.23), Singapore (0.98), Japan (0.80), and United Kingdom (0.47) in terms of equivalent conditions. The risk level of each can be changed when the fatality rate is compared under given equivalent conditions.

Practical Health and Safety Road Map of Global Coalition as a Main Policy for Reduction of Accident Rate in Construction Industry of Uzbekistan

Modern construction industry still remains high risky economic sector in the world. Human factor mainly conceded working at hazardous conditions which caused various disease and accidents. But age of modern science and technology it is proved globally can be solve in effective way. Main purpose of the article is clarifying international health and safety practice standards and its prospective effects and implementation in Uzbekistan construction industry. Main outcomes of the paper work can be presented as best solution for creating safety climate and environment in building industry and increasing professional management system for developing human factor in Uzbekistan. As a conclusion international cooperation on development program on safety regulation and enforcement is directed increasing on social and economic effectiveness of construction industry.