Effects of silicon fume and latex on properties and hydration of modified mortars
Polybutadiene-graft-polystyrene (PB-g-PS) latex with a weight ratio of 50/50 was used to modify cement mortar. This study examines the effects of silicon fume content and the polymer-cement ratios (P/C) on the flow, compressive and flexural strength and water absorption rate of PB-g-PS latex modified cement mortar. The experimental results show that the flow of modified mortar is increased with increasing polymer-cement ratios, and it is decreased with increasing silicon fume content, PB-g-PS latex and suitable silicon fume content can markedly reduce capillary water absorption rate. PB-g-PS latex can marked influences much on the mechanical properties of modified mortars. The compressive of the polymer modified mortar decreased, and the flexural strength of a portion of polymer modified mortar increased. The suitble silicon fume can improve mechanical properties of modified mortats. The effect of PB-g-PS latex and silicon fume content on cement hydration was explored by XRD, the analysis results showed that the cement hydration was influenced by silicon fume content and P/C.
Use of aminosilane coupling agents in cementitious materials
The work presented in this paper has been focused on the evaluation of the influence of the addition of aminosilanes like '-aminopropyltriethoxysilane (3-AMPS) on physical and mechanical properties of fresh and hardened polymer modified cement mortars (PMCMs), which contained also mineral fillers like fumed silica and blast furnace slag. The role of the aminosilane in cementitious system was to produce surface modification and covalent bonding among different inorganic phases of inorganic matrix (cement, aggregate, fumed silica) and strong chemical interaction between inorganic matrix and organic (polymer) phase of the mortar. The strong chemical bonding of inorganic matrix and polymer phase transformed composite mortar into cementitious material with more like monolithic structure. Mortars with the addition of aminosilanes showed improved physical-mechanical properties like bending strength, adhesion to concrete, and lower dry-shrinkage.
Performance properties of concrete repair materials
Abstract Maintenance, repair and strengthening of concrete structures has become a very important part of the activities of the concrete industry. This is reflected in the innumerable proprietary repair materials available in the market and the substantial increase in the number of firms offering specialist maintenance and repair services. Because proprietary compounds are relatively expensive and because the life cost of a repaired structure is also potentially very high, there is much need to provide engineers and specifiers with independent data with which to make appropriate decisions in this field. This paper presents information which arises from a large project on the evaluation of the performance and durability of repair materials being carried out at the Civil Engineering Materials Unit, University of Leeds. The paper includes data on the performance related properties of the following materials: 1. 1. a commercial pre-packed cementitious material; 2. 2. a commercial pre-packed cementitious material modified with polymer; 3. 3. a pozzolanic cement containing 70% ordinary Portland cement and 30% pulverised fuel ash; 4. 4. an ordinary Portland cement containing a commercial organic corrosion inhibitor. The test carried out for evaluation of the repair materials were: compressive strength, bond strength, porosity and permeability The laboratory results are discussed and the implication of potential performance of the repair materials evaluated.