Effects of the fineness of densified silica fume on the hydration of Portland cement

As one of the mineral admixtures, silica fume (SF) with high pozzolanic reactivity is generally used to improve the properties of concrete. Most commercial silica fume used in concrete project is dry densified silica fume (DSF). It consists of a good deal of agglomerates of sizes ranging from 10 μm to several millimeters. The size of the...

Prediction of the chemical shrinkage of Portland cement

Chemical shrinkage is one of the main reasons leading to the early age deformation of concrete. Hence, the prediction of chemical shrinkage is an important issue for evaluating the deformation of concrete and its influence on the durability of concrete structures. There is still room to improve the accuracy for predicting the chemical shrinkage...

Thermodynamic modelling of the reactions of self-healing agents and the chemical binding of aggressive ions in seawater

In this study, a new concept on self healing of cracks that the ingressive ions in the crack is chemically bound to improve the self-healing efficiency was proposed for cracked cementitious materials in a marine environment. Thermodynamic modeling was performed to determine the appropriate masses and ratio of Ca2+ and Al3+ provided by chemical...

A molecular dynamics study of N-A-S-H gel with various Si/Al ratios

The understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the...

The influence of lightweight functional aggregates on the acidification damage in the external anode mortar during cathodic protection for reinforced concrete

Impressed current cathodic protection (ICCP) is an effective corrosion protection and prevention technique for reinforced concrete structures served in chloride-contaminated environment. The acidification damage in the external anode mortar caused by the anodic reactions significantly influences the efficiency of ICCP for reinforced concrete....

Digital Cartographic Model of 3D Cadastre: An Initial Design and Implementation

Despite the abundant research discoveries in 3D cadastre visualization, there still lacks a synthesis method of concreate symbology instructions and 3D graphical content as an easy entry for designers, implementors, and visualization systems. In cartography domain, introducing DCM (Digital Cartographic Model) on top of DLM (Digital Landscape...

The application model of 3D cadastre in practical registration for real estate in China

Since the introduction of the concept of 3D cadastre, a great many of significant research results have been done. To promote the development of 3D cadatre, 3D cadastre working group sponsored by International Federation Surveyors (FIG) commissions 3 and 7 was organized by Delft University of Technology in 2001. This working group provides a...

Bottom-up policy support: Using a construction materials model to identify and quick scan circular opportunities

Although the need for a more circular economy is supported by diverse people in both politics as well as in the scientific community, implementation of circular principles in reality is rarely occurring. This study shows how quantitative models can help to develop new policies for enhancing circularity in the construction sector. By means of a...

A Preliminary Study on the Comprehensive Evaluation of the Disaster Prevention System of Large Urban Underground Space

The original urban planning can never meet the requirements of the rapid development and the increasing population in big cities in China. The best way to solve this problem is to develop the underground space (including tunnels). With the exhaustion and saturation of the shallow underground space, the development of urban area is more and more...

Actuator Fault Detection and Diagnosis for Quadrotors

This paper presents a method for fault detection and diagnosis of actuator loss of effectiveness for a quadrotor helicopter. This paper not only considers the detection of the actuator loss of effectiveness faults, but also addresses the diagnosis of the faults. The detection and estimation of the faults are performed by the Augmented Extended...

Designing a Title Certificate for the Chinese 3D Cadastre

When the land use pattern changes from an extensive way to an intensive way, the development of 3D land-use has become reality. Due to the vertical heterogeneity of property rights, establishment of 3D cadastre is imperative. Meanwhile, registration and certification of the property rights have become important approaches to serve public and...

Logical Design and Implementation of the Data Model for 3D Cadastre in China

The establishment of 3D cadastre is imperative and needs support from legal, organizational and technological aspects. In Shenzhen, China, establishment of 3D cadastre has achievedgreat progress. The joint register mechanism was employedfirstly in Shenzhen, and related research is going on, including definitions, visualization and topological...

On the Refraction of Shock Waves at Fe-Be Interface

The paper aims to investigate the refraction phenomena of shock waves at ferrum-beryllium (Fe-Be) interface. The equations of state of Fe and Be adopt “stiffen gas” formula. For the regular refraction, the shock polar theory is employed. The critical angles of transition of the regular to irregular refraction about the different shock intensity...

Advances in chloride diffusion of concrete exposed to marine field environment

For elaborating the research significance, goal, content and representative results of the concrete marine field exposure experiments all over the world, we have collected a large number of research literature since 1905. The longest exposure test for concrete has reached 62 years and, most importantly, concrete exposure experiments have made...