The Flexural Strength and Fracture Toughness of a Normal and a High Strength Polymer Modified Portland Cement

1984 ◽  
Vol 42 ◽  
Author(s):  
N. B. Eden ◽  
J. E. Bailey
Keyword(s):  
Flexural Strength ◽  
Portland Cement ◽  
Interfacial Shear Strength ◽  
Fracture Behaviour ◽  
High Strength ◽  
Interfacial Shear ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Cement Pastes ◽  
Cement Ratio

AbstractA model has been developed for the flexural strength of Portland cement pastes, based upon observed fracture behaviour of both normal and high strength pastes. Fibrillar or foil-like elements pull apart at a yield stress which is characteristic of the number of elements and interfacial shear strength. The former can be maximised by using a low water/cement ratio and the latter by inclusion of water-soluble polymer, followed by suitable drying. It is proposed that this is the mechanism by which high strength may be attained in Portland cement.

Reactions in the Setting of High Strength Cement Pastes

1984 ◽  
Vol 42 ◽  
Author(s):  
S. A. Rodger ◽  
W. Sinclair ◽  
G. W. Groves ◽  
S. A. Brooks ◽  
D. D. Double
Keyword(s):  
Isothermal Calorimetry ◽  
High Strength ◽  
Water Soluble ◽  
High Alumina ◽  
X Ray Diffraction ◽  
Water Soluble Polymer ◽  
Cement Pastes ◽  
Polymer Addition ◽  
Shear Mixing ◽  
Very High

AbstractMaterials of very high flexural strengths (> IOOMPa) can be made by high shear mixing of cement pastes with small amounts of water soluble polymer. Two such systems - high alumina cement/partially hydrolysed polyvinyl acetate and OPC/polyacrylamide - have been examined using a variety of techniques including isothermal calorimetry, infra-red spectroscopy and X-ray diffraction. In both systems the polymer addition appears to become cross-linked by ions released by the cement powder leading to an increase in stiffness of the material. In particular the reactions involved in the OPC system are analogous to those occurring in certain dental cements. The importance of removing excess water from the pastes is demonstrated.

scholarly journals Enhanced flexural properties of aramid fiber/epoxy composites by graphene oxide

2019 ◽  
Vol 8 (1) ◽  
pp. 484-492 ◽  
Author(s):  
Yinqiu Wu ◽  
Bolin Tang ◽  
Kun Liu ◽  
Xiaoling Zeng ◽  
Jingjing Lu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Flexural Strength ◽  
Interfacial Shear Strength ◽  
Flexural Modulus ◽  
Weight Fraction ◽  
Interfacial Shear ◽  
Aramid Fiber ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Pure Epoxy

Abstract The reinforcing effect of graphene oxide (GO) in enhancing the flexural strength and flexural modulus of aramid fiber (AF)/epoxy composites were investigated with GO-AFs at a weight fraction of 0.1-0.7%. The flexural strength and flexural modulus of the composite reached 87.16 MPa and 1054.7 MPa, respectively, which were about 21.19% and 40.86% higher than those of the pure epoxy resin, respectively. In addition, the flexural properties and interfacial shear strength (IFSS) of composite reinforced by GO-AFs were much higher than the composites reinforced by AFs due to GO improved the interfacial bonding between the reinforcement material and matrix.

The Microstructure of High Strength Cement Pastes

1984 ◽  
Vol 42 ◽  
Author(s):  
W. Sinclair ◽  
G. W. Groves
Keyword(s):  
High Strength ◽  
Water Soluble ◽  
Organic Polymer ◽  
High Alumina ◽  
Cement Pastes ◽  
Alumina Cement ◽  
High Alumina Cement ◽  
Transmission Electron ◽  
Fibrillar Morphology ◽  
Shear Mixing

AbstractThe microstructures of high strength pastes of OPC and high alumina cements prepared by the high shear mixing of a low water/cement ratio paste with water soluble polymers have been studied by transmission electron microscopy. In the case of high strength OPC, the usual hydration products are present, however, the CSH gel lacks the fibrillar morphology often observed in conventional cements. Pastes based on high alumina cement do not contain the normal crystalline calcium aluminate hydrates but a small quantity of gel containing the organic polymer forms a continuous network structure bonding clinker grains. Microanalysis of the polymer phase in high alumina cement revealed the presence of Ca and Al while Ca-rich interstitial gel material was found in OPC pastes.

scholarly journals Physical Properties of Concrete Containing Graphene Oxide Nanosheets

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1707 ◽  
Author(s):  
Yu-You Wu ◽  
Longxin Que ◽  
Zhaoyang Cui ◽  
Paul Lambert
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Graphene Oxide ◽  
Flexural Strength ◽  
Portland Cement ◽  
Physical Properties ◽  
Ordinary Portland Cement ◽  
Construction Materials ◽  
Split Tensile Strength ◽  
Cement Pastes

Concrete made from ordinary Portland cement is one of the most widely used construction materials due to its excellent compressive strength. However, concrete lacks ductility resulting in low tensile strength and flexural strength, and poor resistance to crack formation. Studies have demonstrated that the addition of graphene oxide (GO) nanosheet can effectively enhance the compressive and flexural properties of ordinary Portland cement paste, confirming GO nanosheet as an excellent candidate for using as nano-reinforcement in cement-based composites. To date, the majority of studies have focused on cement pastes and mortars. Only limited investigations into concretes incorporating GO nanosheets have been reported. This paper presents an experimental investigation on the slump and physical properties of concrete reinforced with GO nanosheets at additions from 0.00% to 0.08% by weight of cement and a water–cement ratio of 0.5. The study demonstrates that the addition of GO nanosheets improves the compressive strength, flexural strength, and split tensile strength of concrete, whereas the slump of concrete decreases with increasing GO nanosheet content. The results also demonstrate that 0.03% by weight of cement is the optimum value of GO nanosheet dosage for improving the split tensile strength of concrete.

Microstructure of High Strength Cement Paste Systems

1984 ◽  
Vol 42 ◽  
Author(s):  
M. Regourd
Keyword(s):  
Cement Paste ◽  
Ultrafine Particles ◽  
High Strength ◽  
Interfacial Bond ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Composite Systems ◽  
Crystalline Hydrates ◽  
Low Porosity

AbstractHigh strength cement pastes include hot pressed, autoclaved, impregnated low water/cement ratio, macrodefect free, ultrafine particles arrangement systems. The densification of the microstrucure is mainly related to a low porosity and to the formation of poorly crystalline hydrates. In composite systems like mortars and concretes, the interfacial bond between the cement paste and aggregates is moreover less porous and more finely crystallized than the normal “auréole de transition”.

EM of a macro defect-free cement

1990 ◽  
Vol 48 (4) ◽  
pp. 1068-1069
Author(s):  
O. Popoola ◽  
W. M. Kriven ◽  
J.F. Young
Keyword(s):  
Detailed Examination ◽  
Particle Packing ◽  
Water Soluble ◽  
Cement Particle ◽  
Polymer Interfaces ◽  
Soluble Polymer ◽  
Water Soluble Polymer ◽  
Cement Pastes ◽  
Shear Mixing ◽  
Interparticle Friction

Engineering materials application of silicate or aluminate cements are limited because of their low strength and toughness. These poor properties can be easily attributed to the inherent macro and micro porosity of cement pastes. However in the last decade it has been found that by the addition of a water soluble polymer, high shear mixing and the by application of modest pressure during processing, cement with mechanical properties comparable to most ceramics can be obtained. The water soluble polymer, apart from filling the pores, also act as a rheological aid, reducing the interparticle friction coefficient and providing for optimum particle packing in the microstructure. Although a brief account of the microstructure of this new composite (called Macro Defect Free Cement) has been reported, a close and detailed examination of the cement particle/polymer interface remains to be performed. The aim of this communication is to report the microstructure of a macro defect free cement with particular emphasis on the cement particle/polymer interfaces. Cement nomenclature is used in this report: C= CaO, A= Al2O3, H=H2O

Improving the Flexural Strength of Fibre Reinforced Oil Well Cementsby Addition of a Polymer Latex

1994 ◽  
Vol 370 ◽  
Author(s):  
Demosthenis G. Pafitis
Keyword(s):  
Shear Strength ◽  
Flexural Strength ◽  
Glass Fibre ◽  
Interfacial Shear Strength ◽  
Interfacial Shear ◽  
Cement Matrix ◽  
Oil Well ◽  
Pull Out ◽  
Glass Fibre Reinforced ◽  
Polymer Latex

AbstractFibre-reinforced cements are proving to be useful in various oilfield applications. Low cost and increased toughness render glass fibre reinforced cements of particular interest. In most cases, improvements in toughness are the result of extensive fibre pull-out and this can be clearly observed in electron micrographs of fracture surfaces. This observation implies that there is much scope for improving the interfacial shear strength between the hydrated cement and glass fibres.Experiments have shown that increases in flexural strength and in energy to fracture can be achieved by incorporating small amounts of a polymer latex. Improvements of a factor of four in energy to fracture have been measured when approximately 0.8% by volume of a styrenebutadiene copolymer latex is added to a glass fibre reinforced class G oilwell cement. Experimental results suggest that this effect is not due to improvements in the strength of the cement matrix but due to an enhancement of the interfacial shear strength between fibre and cement.

Microstructure-Property Relationships in Macro-Defect-Free Cement

MRS Bulletin ◽  
1993 ◽  
Vol 18 (3) ◽  
pp. 72-77 ◽  
Author(s):  
Jennifer A. Lewis ◽  
Waltraud M. Kriven
Keyword(s):  
Raw Materials ◽  
Cement Composite ◽  
Water Soluble ◽  
Minimal Amount ◽  
Metal Powders ◽  
Water Soluble Polymer ◽  
Cement Pastes ◽  
Mdf Cements ◽  
Novel Processing ◽  
Entrapped Air

The term “macro-defect-free” refers to the absence of relatively large voids (or defects) that are normally present in conventional cement pastes due to entrapped air or inadequate mixing. A decade ago, Birchall and co-workers developed a novel processing method that avoids the formation of these strength-limiting defects. This method, outlined schematically in Figure 1, consists of mixing hydraulic cement powder, a water-soluble polymer, and a minimal amount of water under high shear to produce a macro-defect-free (MDF) cement composite. Several cement/polymer systems can be processed by this flexible technique, although the calcium aluminate cement/polyvinyl alcohol-acetate (PVA) copolymer system is most common: MDF cements display unique properties relative to conventional cement pastes. For example, the flexural strength of MDF cement is more than 200 MPa as compared to values on the order of 10 MPa for conventional pastes. One can view MDF cements as a type of “inorganic plastic.” As is the case with plastic processing, fillers such as alumina, silicon carbide, or metal powders can be added to MDF cement to modify its performance properties (e.g., abrasion resistance, thermal or electrical conductivity, and hardness). The combined attractiveness of inexpensive raw materials and flexible, low-temperature processing has generated great interest in this new class of advanced cement-based materials.

Studies on premix water-soluble polymer cement pastes - I

1983 ◽  
Vol 13 (2) ◽  
pp. 207-215 ◽  
Author(s):  
R.Sh. Mikhail ◽  
M. Shater ◽  
T.M. El-Akkad
Keyword(s):  
Water Soluble ◽  
Soluble Polymer ◽  
Water Soluble Polymer ◽  
Cement Pastes
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