Concrete is a material both weak and strong. Its durability decreases under negative impact of several chemicals. In particular, when some sulphates in sea and ground waters react with cement paste, concrete expands and cracks; therefore, concrete has a very short life span. In that case, either the effects of sulphates should be suppressed as much as possible, or the performance of concrete sh...

a Faculty of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, PR 5 China 6 b Concrete Durability Group, Department of Civil and Environmental Engineering, Imperial College London, 7 SW7 2AZ, UK 8 9 ABSTRACT 10 11 In this study, the influence of the aggregate-cement paste interfacial transition zone (ITZ) on the steady-state 12 chloride diffusivity of morta...

In a pioneering work, Powers and Brownyard (1948) were the first to systematically investigate the reaction of cement and water and the formation of cement paste. In the late 1940s they presented a thorough model of the cement paste, in which unreacted water and cement, the hydration product, and (gel and capillary) porosity were considered. Via extensive and carefully executed experiments majo...

Grating-based X-ray dark-field tomography is a promising technique for biomedical and materials research. Even if the resolution of conventional X-ray tomography does not suffice to resolve relevant structures, the dark-field signal provides valuable information about the sub-pixel microstructural properties of the sample. Here, we report on the potential of X-ray dark-field imaging to be used ...

It is with great interest that we read the article by Seo et al, “Percutaneous Osteoplasty for the Treatment of a Painful Osteochondral Lesion of the Talus: A Case Report and Literature Review,” published in the 2012 September/October issue of Pain Physician (1). This is a well-prepared case report which presents a novel surgical procedure using calcium polyacrylatehydroxyapatite cement in perc...

New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images o...

Superplasticizers are a class of anionic polymer dispersants used to inhibit aggregation in hydraulic cement, lowering the yield stress of cement pastes to improve workability and reduce water requirements. The plant-derived biopolymer lignin is commonly used as a low-cost/low-performance plasticizer, but attempts to improve its effects on cement rheology through copolymerization with synthetic...

Calcium phosphate cement (CPC) sets in situ with intimate adaptation to the contours of defect surfaces, and forms an implant having a structure and composition similar to hydroxyapatite, the putative mineral in teeth and bones. The objective of the present study was to develop an injectable CPC using dicalcium phosphate dihydrate (DCPD) with a high solubility for rapid setting. Two agents were...

This study successfully applied multi-mode laser cutting with the variation of the laser cutting speed to cement mortar for the first time. The effects of the amount of silica sand in the cement mortar on laser cutting are tested and analyzed. The kerf width and penetration depth of the specimens after laser cutting are investigated. As the laser cutting speed increases, the penetration depth d...

A flatbed scanner is used to collect a digital image of a polished cross-section through a concrete pavement. Image processing software is used to classify each pixel in the image as either cement paste, aggregate, or air void. The distance to the nearest air void is calculated for each pixel classified as cement paste using an accumulated cost surface algorithm. The presence of aggregate is ac...