Showing papers on "Mortar published in 1972"

Measuring the fracture toughness of cement paste and mortar

Abstract: Synopsis This paper describes two methods that have been used to measure the effective fracture toughness of cement pastes and mortars. The first is a notched-beam technique, combined with compliance measurements to measure the slow crack growth prior to instability. The change of toughness is measured for separate increments of crack growth as the crack propagates. The second method, using a double-cantilever beam, avoids the slow crack growth problem by making a specimen of variable web width such that the length of crack front increases with and exactly compensates for the effect of crack growth. Tests of both pastes and mortars show that the fracture toughness of cement paste is independent of crack growth but that the toughness of mortar increases as the crack propagates. For both materials, the stress intensity required to initiate crack growth was less than that to maintain crack growth at the loading rates used.

Mortar compositions containing mixtures of hydroxyalkyl celluloses

Abstract: IMPROVED AQUEOUS MORTAR COMPOSITIONS CONTAIN A MINOR AMOUNT OF A MIXTURE OF (1) HYDROXYPROPYL CELLELOSE AND (29 HYDROXYMETHYL CELLULOSE OR HYDROXYETHYL CELLULOSE OR MIXTURES THEREOF. COMPOSITIONS IN ACCORDANCE WITH THE PRESENT INVENTION CAN BE FORMULATED TO EFFECT QUICK SOLUTION AND PRODUCE A STABLE VISCOSITY THROUGH TIME AND TEMPERATURE CONDITION OF USE.

Factors affecting the flexural strength of steel fibrous concrete

Abstract: AN INVESTIGATION WAS MADE OF THE EFFECTS OF STEEL FIBER PARAMETERS AND CONCRETE MIX PARAMETERS ON THE FLEXURAL STRENGTH PROPERTIES OF STEEL FIBROUS CONCRETES AND MORTARS. COMPOSITIONS WERE EVALUATED IN WHICH THE STEEL FIBER CONTENT WAS AS HIGH AS 4.0 VOLUME PERCENT. DATA ARE PRESENTED WHICH SHOW THE RELATIONSHIP OF FIBER CONTENT AND FIBER SPACING ON THE ULTIMATE AND FIRST CRACK FLEXURAL STRENGTH OF A STANDARD MORTAR FORMULATION. THE EFFECT OF MIX WORKABILITY AS CONTROLLED BY THE MIX COMPOSITION ON THE FLEXURAL STRENGTH PROPERTIES IS DISCUSSED. THE EFFECT OF COARSE AGGREGATE ADDITIONS ON THE FLEXURAL STRENGTH OF A STEEL FIBROUS MORTAR IS ALSO DISCUSSED. THE USE OF STEEL WIRE FIBERS PROVIDES SIGNIFICANT IMPROVEMENTS IN THE FLEXURAL STRENGTH PROPERTIES OF CONCRETES AND MORTARS WHEN THE PROPER CONDITIONS OF MIX FORMULATION, BATCHING, AND PLACING ARE ACHIEVED. /ACI/

Masonry wall constructing process

Abstract: A process for forming a masonry wall member from a plurality of individual blocks bonded by mortar is disclosed. The blocks are arranged in a mold in a predetermined pattern and the mold closed to hermetically seal the mold and maintain the blocks therein in spaced relationship. A source of mortar is connected to the interior of the mold and a vacuum is created within the mold by means of a vacuum pump. When the desired evacuation is reached, further pressure reduction is discontinued while retaining the vacuum within the mold. The mortar is then permitted to flow into the mold to completely fill the interstices between the blocks as well as pores therein. A positive pressure may also be applied to the mortar to additionally facilitate filling of the mold with mortar.

Set retarder and air-entrainer composition for mortar

Abstract: A mortar set retarder and air-entrainer composition comprising an aqueous solution of sodium tripolyphosphate, a water-soluble ethylene oxide condensation product and a wetting agent. The retarder may optionally include a polyamino polycarboxylic acid.

Adjuvants for mortar or filler compsns - added in microcapsulated form

Abstract: The adjuvant may be a liquid or emulsion of high viscosity. The compsn. is mixed with water and worked up, the adjuvant being thereby slowly released.

Further study of double-punch test for tensile strength of soils, 1972

Abstract: This paper presents the theoreti.cal and experimental studies of the newly developed double-punch test method for determination of the tensile strength of compacted soils. Some factors that may effect the doublepunch test are studied. These factors include sample-punch size, rate of loading, compressive strength, and soil types. The comparis'ons of tensile tests determined from double-punch and split tensile tests for various materials including concrete, mortar, rock, and stabilized materials are also presented. lAssociate Professor of Civil Engineering and Director, Geotechnical Engineering Division, Fritz Engineering Laboratory, Lehigh University. 2Associate Professor of Civil Engineering, Fritz Engineering Laboratory, Lehigh University.

Polymer Latex Modified Mortar

Abstract: POLYMER LATEX MODIFIED MORTARS ARE PORTLAND CEMENT MORTARS TO WHICH POLYMER LATEX EMULSIONS HAVE BEEN ADDED DURING MIXING. MECHANICAL AND DURABILITY PROPERTIES OF MODIFIED MORTARS, THE EFFECTS OF CURING HISTORY ON MODIFIED MORTARS AND LATEX FILMS, AND BOND STRENGTH OF MODIFIED MORTAR TO PLAIN MORTAR WERE STUDIED. SIGNIFICANT IMPROVEMENTS WERE OBSERVED IN EXTENSIBILITY, BONDING PROPERTIES, AND DURABILITY OF MORTAR. HENCE, MORTAR MODIFIED BY LATEX EMULSION MAY BE USEFUL FOR SURFACE COATINGS, PAVEMENT TOPPINGS, AND PATCHING OF DAMAGED CONCRETE. HIGHER VOLUME CHANGES DURING WETTING AND DRYING, LOWER MODULUS OF ELASTICITY, AND LOWER COMPRESSIVE STRENGTH WERE OBSERVED FOR MODIFIED MORTARS. ALTHOUGH CONTINUOUS WET CURING REDUCES THE STRENGTH OF MODIFIED MORTAR, SUBSEQUENT DRYING INCREASES THEIR STRENGTHS. FOR POLYVINYL ACETATE EMULSIONS, THIS WAS PARTLY EXPLAINED BY THE PERFORMANCE OF LATEX FILMS IN SATURATED LIME SOLUTIONS. /AUTHOR/

Method for forming a body of concrete or similar material in the soil

Abstract: A method of forming a body of concrete or similar material in the soil comprises the steps of making a hole in the soil, lowering into said hole a bag having a shape corresponding to that of the body to be formed and made of a flexible material which is water-permeable but substantially blocks the passage of the solid particles of the (concrete) mortar and filling said bag with the (concrete) mortar, whereby the bag is subjected to vibrations either during and/or directly after the filling.

Building element aligner and mortarizer

Abstract: A method to aid in the construction of walls of bricks or other building elements providing for laying the building elements in random alignment in a course on a layer of mortar, alignment of said building elements with side faces of the wall being built and at the same time applying a layer of mortar on the aligned building elements for the next course of randomly aligned building elements, said aligning and mortar application being by a machine adapted for running on said randomly laid and the aligned and mortared building elements. The machine for applying the method comprises a mortar container having a downwardly diverging mortar outlet, spaced aligning devices and supporting runners which are disposed on opposite sides of the outlet.

Mortar mixing system

Abstract: A system for producing dry mortar mix and at a remote location, transporting the dry mix to the construction site and then mixing the dry mix with water producing the mortar. The system includes a building having three separate compartments for patent mortar, additive and sand. An endless conveyor belt conveys sand from a sand dump to the sand compartment with the conveyor belt extending through a heat insulated tunnel with electrical coils positioned adjacent the length of the conveyor belt for heating the sand and reducing the moisture content in the sand. The three compartments exit into a drum pivotally mounted to the building which has a rotatably driven paddle for mixing the patent mortar, additive and sand. The drum is pivoted downwardly to dump the dry mix into a hopper mounted to the side wall of the building. A rotatably driven auger conveys the dry mix from the hopper upwardly into a chute which opens into a dry mix compartment of a vehicle therebeneath for transportation to the job site where dry mortar is augered into a job trailer. The trailer has a water storage tank and a dry mix compartment allowing the mortar to be prepared as needed in smaller quantities.

Latex-modified mortar compositions

Abstract: THE INVENTION IS DIRECTED TO HIGH STRENGTH PORTLAND CEMENT MORTAR COMPOSITIONS MODIFIED WITH CERTAIN VINYLIDENE CHLORIDE POLYMER LATEXES AND CONTAINING IN ADDITION, SPECIFIED TYPES OF FINELY DIVIDED NATURALLY OCCURRING CARBONATE MATERIALS COMPOSED OF A NATURAL CARBONATE CONSISTING OF THE MINERALS CALCITE, DOLOMITE AND NAGNESITE WHICH MAY COMPRISE A CONTINUOUS GRADATION FROM CALCIUM CARBONATE THROUGH CALCIUM MAGNESIUM CARBONATE TO MAGNESIUM CARBONATE. IT HAS UNEXPECTEDLY BEED FOUND THAT THE ADDITION OF SUCH CARBONATE MATERIALS GREATLY ENHANCES THE WORKABILITY OF THE LATEX-MODIFIED PORTLAND CEMENT MORTAR COMPOSITIONS WITHOUT ADVERSELY AFFECTING THE STRENGTH CHARACTERISTICS OF SUCH COMPOSITIONS.

Tensile strength reduction of mortar and concrete due to moisture gradients

Abstract: BECAUSE OF THE TENDENCY OF HYDRATED PORTLAND CEMENT TO SHRINK OR SWELL WITH LOSS OR GAIN OF WATER, MOISTURE GRADIENTS PRODUCED BY RAPID DRYING MAY INDUCE STRESSES IN CONCRETE AND MORTAR. THE RESEARCH DESCRIBED HERE SHOWS THAT THESE STRESSES CAN BE OF SUFFICIENT MAGNITUDE TO REDUCE SIGNIFICANTLY THE TENSILE STRENGTH OF CONCRETE AND MORTAR. THE FOLLOWING SPECIFIC CONCLUSIONS ARE REPORTED: (1) THE TENSILE STRENGTHS OF MORTAR AND CONCRETE ARE SIGNIFICANTLY LOWER DURING THE INTERMEDIATE STAGES OF RAPID DRYING THAN FOR THE SATURATED CONDITION. (2) THE MAXIMUM STRENGTH REDUCTIONS OCCUR WHEN ABOUT HALF OF THE EVAPORABLE WATER HAS BEEN REMOVED. (3) THE MAGNITUDE OF THE MAXIMUM STRENGTH REDUCTIONS, AS COMPARED WITH THE SATURATED STATE, ARE 30--35%. (4) ABOVE 100 DEGREES C DRYING-TEMPERATURE VARIATIONS DO NOT SIGNIFICANTLY AFFECT THE MAGNITUDE OF STRENGTH REDUCTION. (5) THE STRENGTH REDUCTION OBSERVED AT INTERMEDIATE MOISTURE CONTENTS IS APPARENTLY DUE TO THE PRESENCE OF STEEP MOISTURE GRADIENTS LEADING TO INDUCED TENSION FROM DIFFERENTIAL SHRINKAGE. (6) THE TENSILE STRENGTH OF COMPLETELY DRY CONCRETE IS SIGNIFICANTLY LESS THAN THAT OF SATURATED CONCRETE, PROBABLY AS A RESULT OF RESIDUAL TENSILE STRESSES IN THE PAST OF THE DRY CONCRETE. (7) THE TENSILE STRENGTH OF COMPLETELY DRY CONCRETE IS SIGNIFICANTLY GREATER THAN THAT AT INTERMEDIATE SATURATION LEVELS DURING DRYING.

Concrete or mortar for heat and sound insulating building - elements - based on binder and ground rubber

Abstract: Concrete comprises cement or gypsum; accelerators gas formers e.g., Mg, Al powder, CaCl2; and waste rubber e.g., from tyres ground to a particle size is not >10 mm. with a wt. ratio of binder to rubber of 10-70: 90-30. Water glass and fire resisting chemicals e.g., phosphates, Cl and Sb contg. compounds may also be included.

Method for determining resistance of mortars to sulfate attack

Abstract: Recognizing that the sulfate resistance of mortars is affected by conditions of use, temperature, cement content, plasticity, and mortar defects, particularly those of aggregate-cement bonding, a new test for sulfate resistance was developed. Samples 2 by 2 by 10 cm are half-immersed in an MgSO4 solution. The appearance and compressive strengths of the immersed and exposed parts are recorded at intervals and compared with those of water-stored samples. This method is quantitatively reliable, selective, rapid, and inexpensive. Results for cements tested in this way are presented, and the physical and chemical characteristics of durable mortars are elucidated. The test was used to demonstrate the sulfate resistance of a new calcium silicate cement.

An apparatus for determining the coefficient of thermal expansion of rocks, mortars and concretes

Abstract: Synopsis An apparatus for the determination of the coefficient of thermal expansion in the temperature range 20 to 80°C of rock, mortar and concrete specimens is described The moisture content of the specimens can vary from oven-dried to saturation Data showing the thermal expansion of rocks and mortars are presented

Techniques for retarding the penetration of deicers into cement paste and mortar

Abstract: The corrosion of reinforcing steel in concrete bridge decks is a result of the presence of chlorides. Factors affecting the penetration of deicing salts were studied with hydrated cement pastes and mortars as the penetration medium. The most effective retardation technique was impregnation with methyl methacrylate monomer and subsequent polymerization by irradiation. Part of the investigation also included efforts to develop means of reducing dangerous chloride levels already existent in concrete. A back-flushing technique was effective in reversing chloride penetration to a limited extent. This presentation is a condensation and update of an Interim Report by the same authors, No. PB 219 833, available from the National Technical Information Service.

Polymer resins as admixtures in portland cement mortar and concrete

Abstract: THIS REPORT COVERS THE STUDIES MADE ON TWO ADMIXTURES FOR CONCRETE THAT WERE INVESTIGATED PRIMARILY FOR THEIR USE AS OVERLAYS OR AS PATCHING MATERIALS FOR BRIDGE DECKS. THE FIRST, EPOXON, IS A MIXTURE OF POZZOLAN AND A TWO-COMPONENT EPOXY RESIN EMULSION. THE SECOND, TUFCHEM, IS AN "ORGANIC WATER-SOLUBLE POLYMER." WHEN COMPARED WITH NORMAL CONCRETE, IT WAS FOUND THAT: EPOXON MODIFIED CONCRETE EXHIBITED INCREASED STRENGTHS FOR CONCENTRATIONS OF 20 PERCENT EPOXY RESIN OR LESS BASED ON THE WEIGHT OF THE CEMENT, SATISFACTORY BOND-TO-CONCRETE, AND INCREASED RESISTANCE TO ATTACK BY SULFURIC ACID. TUFCHEM MODIFIED CONCRETE EXHIBITED INCREASED EARLY STRENGTH, INCREASED EARLY SHRINKAGE, AND DECREASED BOND-TO-STEEL AND HARDENED CONCRETE. BOTH MATERIALS SHOWED ADEQUATE FREEZE-THAW RESISTANCE, RESISTANCE TO SCALING, TO ABRASION, AND TO SKIDDING. /AUTHOR/

Contribution to the study of fresh concrete rheology

Abstract: THE THREE-PART STUDY DESCRIBED DEALS WITH (1) MEASUREMENTS MADE TO ASSESS THE RHEOLOGY OF MORTAR, (2) RHEOLOGICAL BEHAVIOUR OF MORTAR, AND (3) THE INFLUENCE OF MORTAR MIX DESIGN ON ITS VISCOSITY. THIS ARTICLE IS CONCERNED ONLY WITH THE FIRST TWO PARTS. DETAILS ARE GIVEN OF AN APPARATUS DEVELOPED FOR DETERMINING THE FLOW CURVE OF THE MATERIAL AND THUS DERIVING AN EQUATION FOR ITS RHEOLOGICAL STATE. CHANGES IN RHEOLOGICAL BEHAVIOUR WERE CLEARLY SHOWN DPENDING ON THE DYNAMIC CONDITIONS TO WHICH THE MATERIAL WAS SUBJECTED (VIBRATION OR NO VIBRATION), ON THE CONCENTRATION OF SOLID PARTICLES AND SHAPE OF AGGREGATES. AN INVESTIGATION WAS CONDUCTED INTO THE INFLUENCE OF THE CONCENTRATION OF SOLID MATTERS, PARTICLE SIZE DISTRIBUTION, SHAPE AND NATURE OF AGGREGATES ON THE VISCOSITY OF FRESH MORTAR, VIBRATED OR NOT.

Cement Mortar Lining of 20-Ft Diameter Steel Pipe

Abstract: The art of cement mortar lining new steel pipelines, already installed, has advanced rapidly in the past 10 yrs. This advancement has led to the application of in-place mortar lining in a 20 ft-diam steel tunnel. This application has been described by showing there was a need for a faster and better way to apply a protective coating to large diameter steel conduits. The description includes where and how this application was performed.

Mortars and concrete

Abstract: Mortar for brickwork is composed of a matrix, lime or cement, and an aggregate, usually sand. If the most suitable mortar is to be selected and subsequent defects avoided it is necessary to appreciate the basic properties of the materials of which the mortar is composed.

Effect of aggregate on the fracture process of concrete

Abstract: The study was carried out to see how the amount of aggregate in a matrix affects the fracture process of mortar and concrete. Crack arresting action of matrix-aggregate interfaces was studied by means of fracture indices, in accordance with Griffith's concept. In all of the tests the properties of matrices were fixed. From test results fracture process seems to depend largely on the amount and shape of the aggregate. Within a certain aggregate ratio where the properties of matrices do not change, critical strain energy release rate or fracture toughness and critical stress intensity factor of mortar and normal concrete increased with an increase of aggregate volume ratio, while that of lightweight concrete decreased. The rate of increase seems to relate to the aggregate shape. These tendencies were verified by model analysis. (A) See also IRRD Abstract No. 205029

Repairing cracked building foundations - with epoxy resin mortar pure epoxy resin and reinforcing iron bars

Abstract: The crack is first widened into a straight line and then depth preserved and a smooth surfaced epoxy resin mortar trowelled on. Pref. several 25 - 35 mm. dia. holes are bored at an angle of 45 degrees - 60 degrees from above the crack to below it after which the holes are packed with pure epoxy resin with the aid of a low pressure compressor. Finally iron bars are pushed into the bore holes.

The effect of mix proportions upon the ultimate air-drying shrinkage of mortars

Abstract: Synopsis Values are given for the ultimate air-drying shrinkage of 25 mm square mortar and paste prisms moist-cured for one week and dried at 65% R.H. and 20°C. The mortars, of water/cement ratios 0·35, 0·47, 0·59 and 0·71 and aggregate volume concentrations ranging from 40 to 70%, were made from one hatch of all ordinary Portland cement and Thames Valley flint aggregate of 5 mm maximum size. The ultimate shrinkages of the mortars are plotted as contours on a ternary diagram of mix proportions by weight and it is shown that ultimate shrinkage of the mortars is approximately proportional to water content by weight in the original mix. A comparison is made between theoretical predictions of shrinkage and the experimental values.

Thermal Diffusivity of Concrete as a Composite Material

Abstract: Concrete can be regarded as a composite material composed of cement paste or mortar as a matrix and gravel as an aggregate. Thermal diffusivity is a measure of material's ability to undergo a temperature change. In this study, the thermal diffusivity of concrete was measured and the results were examined from the viewpoint of a composite material.When both of the fine and the coarse aggregates are of the same rock type, the diffusivity of the concrete shows a tendency to increase with increasing the aggregate content. When they are different, however, such tendency no longer exists. Hence the rock type is one of the most important factors which determine the diffusivity of concrete.Since the exact value of diffusivity of aggregate is generally unknown, a model coarse aggregate was made of the mortar of known diffusivity and was used to make concrete samples. The measurement of the diffusivity on these samples showed that the diffusivity of concrete can be expressed in terms of the diffusivities and the volume fractions of the constituent materials. This result can be used to estimate an unknown diffusivity of aggregate, mortar or concrete when two of these three quantities are known.

Mortar - contg a polyester,a catalyst and a filler

Abstract: The polyester contains a highly flexible copolymer and an an essentially rigid copolymer, the former having low visc and being present in wt ratio 2:1 to 5:1 wrt rigid copolymer; and the mortar compsn undergoing shrinkage, on curing, of not more than 1 vol% Pref the initial viscosity of the flexible polymer is 6 cP