Cement

About: Cement is a research topic. Over the lifetime, 68440 publications have been published within this topic receiving 829356 citations.

Handbook of Polymer-Modified Concrete and Mortars: Properties and Process Technology

Abstract: Polymer-modified or polymer cement mortar (PCM) and concrete (PCC) are materials that deal with concrete-polymer composites. They are made by partially replacing the cement hydrate binders of conventional cement mortar or concrete with polymers, such as polymeric admixtures or cement modifiers, and by strengthening the binders with the polymers. The polymeric admixtures or cement modifiers include latexes, emulsified polymers, redispersible polymer powders, water-soluble polymers, liquid resins, and monomers. The composite concrete and mortars are currently used as popular construction materials. This book brings together the current knowledge and information of PCMs and PCCs and discusses or reviews the following items in detail: principles of polymer modification for cement composites, process technology of PCMs and PCCs, properties of PCMs and PCCs, applications of PCMs and PCCs, and special polymer-modified systems such as MDF cements, antiwashout underwater concretes, polymer-ferrocements, and artificial woods. An index and chapter references are included.

Influence of nano-SiO2 on the Portland cement pastes

Abstract: The evolution of nanotechnology provides materials with new properties and over the last years a lot of effort has been put to introduce nano-particles into cement pastes in order to improve their properties and to produce materials of better performance. In the present research work, nano-SiO2 produced by pyrolysis and with specific area of 200 m2/g has been added at different percentages (0%, 0.5%, 1%, 2% and 5%) to high-strength cement pastes. These pastes were tested for their mechanical and structural properties at different ages. Nanoparticles act as nuclei for crystallization and large, idiomorphic crystals of Ca–Si composition were formed assisting, up to a certain percentage, in producing materials with dense structure, reduced porosity and improved strength.

Strength development of ternary blended cement with limestone filler and blast-furnace slag

Abstract: The benefits of limestone filler (LF) and granulated blast-furnace slag (BFS) as partial replacement of portland cement are well established. However, both supplementary materials have certain shortfalls. LF addition to portland cement causes an increase of hydration at early ages inducing a high early strength, but it can reduce the later strength due to the dilution effect. On the other hand, BFS contributes to hydration after seven days improving the strength at medium and later ages. Mortar prisms in which portland cement was replaced by up to 20% LF and 35% BFS were tested at 1, 3, 7, 28 and 90 days. Results show that the contribution of LF to hydration degree of portland cement at 1 and 3 days increases the early strength of blended cements containing about 5–15% LF and 0–20% BFS. The later hydration of BFS is very effective in producing ternary blended cements with similar or higher compressive strength than portland cement at 28 and 90 days. Additionally, a statistical analysis is presented for the optimal strength estimation considering different proportions of LF and BFS at a given age. The use of ternary blended cements (PC–LF–BFS) provides economic and environmental advantages by reducing portland cement production and CO2 emission, whilst also improving the early and the later compressive strength.

Impact strength of a few natural fibre reinforced cement mortar slabs: a comparative study

Abstract: This paper presents the experimental investigations of the resistance to impact loading of cement mortar slabs (1:3, size: 300 mm × 300 mm × 20 mm) reinforced with four natural fibres, coir, sisal, jute, hibiscus cannebinus and subjected to impact loading using a simple projectile test. Four different fibre contents (0.5%, 1.0%, 1.5% and 2.5%—by weight of cement) and three fibre lengths (20 mm, 30 mm and 40 mm) were considered. The results obtained have shown that the addition of the above natural fibres has increased the impact resistance by 3–18 times than that of the reference (i.e. plain) mortar slab. Of the four fibres, coir fibre reinforced mortar slab specimens have shown the best performance based on the set of chosen indicators, i.e. the impact resistance (Ru), residual impact strength ratio (Irs), impact crack-resistance ratio (Cr) and the condition of fibre at ultimate failure.

Influence of a fine glass powder on the durability characteristics of concrete and its comparison to fly ash

Abstract: A detailed investigation carried out to ascertain the durability characteristics of fine glass powder modified concretes is reported in this paper. Tests were designed to facilitate comparisons between concretes modified with either glass powder or fly ash at the same cement replacement level. The optimal replacement level of cement by glass powder is determined from strength and hydration tests as 10%. The later age compressive strengths of glass powder and fly ash modified concretes are seen to differ by only 5%. The durability characteristics are ascertained using tests for rapid chloride permeability, alkali–silica reactivity, and moisture transport parameters. The chloride penetrability values indicate some amount of pore refinement. The potential of glass powder to reduce the expansion due to alkali–silica reaction is established from tests conducted in accordance with ASTM C 1260, but fly ash is found to perform better at similar replacement levels. Glass powder–fly ash blends that make up a 20% cement replacement level are found to be as efficient as 20% fly ash in reducing expansion. The control concrete is seen to exhibit the lowest overall moisture intake after 14 days of curing, and fly ash concrete the highest, with the glass powder concrete in between. The trend is reversed at later ages, demonstrating that both the replacement materials contribute to improved durability characteristics. The sorptivity and moisture diffusion coefficient values calculated from the moisture intake-time data also demonstrate a similar trend. These studies show that fine glass powder has the potential to improve the durability of concretes.