6 – Hydration, Setting and Hardening of Portland Cement

Determination of carbonation profiles in non-hydraulic lime mortars using thermogravimetric analysis

A reinforced, lightweight, dimensionally stable panel capable of resisting shear loads when fastened to framing equal to or exceeding shear loads provided by plywood or oriented strand board panels. The panels employ a core of a continuous phase resulting from the curing of an aqueous mixture of calcium sulfate alpha hemihydrate, hydraulic cement, an active pozzolan and lime, the continuous phase being reinforced with alkali-resistant glass fibers and containing ceramic microspheres, or a blend of ceramic and polymer microspheres, or being formed from an aqueous mixture having a weight ratio of water-to-reactive powder of 0.6/1 to 0.7/1 or a combination thereof. At least one outer surface of the panels may include a cured continuous phase reinforced with glass fibers and containing sufficient polymer spheres to improve nailability or made with a water-to-reactive powders ratio to provide an effect similar to polymer spheres, or a combination thereof.

Structural sheathing panels

Lime has been used in construction for millennia, and its value, especially in the field of conservation architecture, has only recently been rediscovered. Lime mortars harden through carbonation, and this thesis is a study of that process. The research conducted has resulted in the development of two novel techniques for the measurement and detection of carbonation. The first technique is a method of thermogravimetric analysis which allows the carbonation profile to be measured within an acceptable time-frame. The second technique is the use of drilling resistance measurement to visualise the carbonation profile. The potential of elemental analysis to measure the carbonation profile has also been identified. It has been demonstrated that the lime/water ratio has less impact on the compressive strength of air lime mortars than had previously been supposed. The change in the pore size distribution of air lime mortars caused by carbonation has been studied, and a theory has been proposed to explain this phenomenon. Five different forms of air lime binder were studied. The impact of these on the structural performance of the resultant mortars has been assessed. It was concluded that mortars made with lime putties perform better than mortars made with dry lime hydrate. Mortars made with dispersed hydrated lime appear to perform as well as mortars made with lime putties, but at a slower rate of strength growth. The use of extra mature lime putty does not appear to confer structural performance benefits when compared with ordinary lime putty. It has been shown that the use of calcitic aggregates can produce air lime mortars which perform as well as moderately hydraulic lime mortars. It is theorised that this phenomenon is not directly related to carbonation, but rather to a complex interaction of the granulometry, mineralogy, chemistry and porosity of the aggregate with the binder.

A study of carbonation in non-hydraulic lime mortars

A composition for use in construction materials, which may be substituted for high performance concrete, patching materials, joint compounds, and the like, such as backer boards or panels, which includes a settable calcium sulfate, preferably a hemihydrate, Portland cement, a finely divided pozzolanic material, lime, and an aggregate, optionally including other additives. The volume ratio of the aggregate to the combined calcium sulfate, Portland cement, pozzolanic material, and lime (a cementitious binder) is equal to or greater than 2/1. Panels made from this composition are useful, particularly when exposed to water since they have good dimensional stability.

Gypsum-cement system for construction materials

HYDRAULIC BINDERS AND BUILDING ELEMENTS FORMED OF NON-TRADITIONAL MATERIALS A process is disclosed for the formation of hydraulic binders and building elements comprising from 70% ettringite and up to 30% calcium silicate hydrates. Ettringite is a very strong mineral and the product may be at least the equal in terms of mechanical properties of Portland cement while not suffering shrinkage and expansion problems. The process comprises mixing powdered source materials of reactive CaSO4, CaO and Al2O3 with or without SiO3 with or without SiO2 and hydrating the intimate mixture at a ratio in the range of 1 part powdered source materials to 0.35-1 part water. Most conveniently, impure source material such as industrial by-products are used as they have been found to catalyse the hydration reaction. Further if gypsum is a powdered source material, in a natural, pure or chemical form, it is preferably calcined since such material sets quickly and gives early mechanical strength. A clinker of calcium sulphoaluminate may be produced for use as a powdered source material.

Hydraulic binders and building elements formed of non-traditional materials

On essaye d'expliquer la difference entre les valeurs d'hydroxyde de calcium obtenues par methode chimique (methode de Franke) et par analyse thermique en faisant intervenir une reaction partielle de l'hydroxyde de calcium avec CSH au cours du chauffage de l'echantillon dans un intervalle de temperature precedant la decomposition thermique de Ca(OH) 2

Quantitative determination of calcium hydroxide in the presence of calcium silicate hydrates. Comparison between chemical extraction and thermal analysis

Etude de l'influence du fluorure de calcium, oxyde cuivrique et fluorure de cuivre sur la synthese de β-C 2 S pur et son hydratation. On montre que l'influence de la temperature sur le degre d'hydratation depend de la nature du mineralisateur

Influence of some mineralizers on synthesis and hydration ofβ-dicalcium silicate

DTA study of the influence of lime content of low-calcium fly ashes on the pozzolanic reaction

Etude du comportement hydraulique d'un silicate bicalcique synthetique en presence de trois additifs ajoutes separement a l'eau: fluorure de sodium, formiate de calcium, sulfate d'aluminium

Gian Lorenzo Valenti

Papers

Hydraulic binders and building elements formed of non-traditional materials

Quantitative determination of calcium hydroxide in the presence of calcium silicate hydrates. Comparison between chemical extraction and thermal analysis

Influence of some mineralizers on synthesis and hydration ofβ-dicalcium silicate

DTA study of the influence of lime content of low-calcium fly ashes on the pozzolanic reaction

Effect of some accelerating admixtures on the hardening of ß-dicalcium silicate